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Executive Summary:
EFFESUS, an acronym for Energy Efficiency for EU Historic Districts’ Sustainability, is a research project which has received funding from the European Union’s Seventh Framework Programme, under Grant Agreement No. 314678, running from 2012 to 2016 and involving 25 partners from 13 European countries.
EFFESUS is researching the energy efficiency and sustainability of European historic urban districts and investigating measures and tools to make significant improvements whilst protecting their heritage value. Historic urban districts are an integral, important part of European cultural identity and heritage. Improving their energy efficiency sensibly will help to protect this heritage for future generations. EFFESUS has adopted an inclusive definition of historic urban districts: a significant group of buildings, built before 1945 and representative of the period of their construction or history, and comprising buildings which are not necessarily protected by heritage legislation. The European building stock built before 1945 represents 23% of the total and, even if a reduced number of these buildings are officially listed, a substantial proportion possess heritage significance.
Most of exiting development in energy efficiency address new construction without dealing with the uniqueness of historic structures. Furthermore, new solutions typically address individual buildings without considering the urban dimension, where interconnections between buildings and other infrastructures enable different solutions. EFFESUS has developed new technologies; produced a software tool to inform decisions on improvement measures; provided training and awareness activities; and demonstrated its results in seven historic urban districts.
EFFESUS has produced the Decision Support System, a software tool, to help make informed decision about improvement measures suitable for historic urban districts. The decision making is supported by a multiscale spatial data model, a categorisation of historic buildings and districts and a repository energy efficiency retrofit solution. The project has developed and implemented new and adapted technologies and systems which are cost-effective and technically and visually suitable for use in historic buildings and districts. These technologies include insulating mortars, radiant reflective coatings, aerogel insulation and secondary window solutions, intelligent energy management systems and systems for the energy generation from renewable sources.
EFFESUS has demonstrated in seven real case studies the applicability of its technological developments and the suitability of its software tool. The project results from EFFESUS were and will be widely disseminated throughout Europe, to engage with as large an audience as possible.
EFFESUS has categorised European historic districts and developed a multiscale data model through the collection and analysis of data. The project ensured that any technical and non-technical barriers, preventing the implementation of the project results, can be overcome by the involvement of different stakeholders in order to exploit research results.
The applicability and suitability of the technologies and systems developed through EFFESUS as well the Decision Support System were demonstrated at real scale. The case studies are located in historic districts of seven European cities of very different building traditions, climatic conditions and cultural contexts. All case studies, except for Glasgow, are located in UNESCO World Heritage Sites.

Project Context and Objectives:
Buildings have a significant impact on energy use and the environment. Across the European Union, they are responsible for approximately 40% of the energy consumption and 36% of CO2 emissions. The majority of buildings in Europe are located in cities, which accommodate around 73% of the population, a share which is expected to increase to over 80% by 2050. Growth in population, increasing demand for building services and high comfort levels assure that the upward trend in energy demand will continue in the future.
The European Union has developed several programmes, guidelines and directives on energy efficiency in buildings in order to harmonise instruments and criteria, such as the recast of the Energy Performance of Buildings Directive 2010/31/EU (EPBD), which strengthen energy performance requirements; or the European Recovery Plan which considers energy efficiency as one of the actions to be tackled to overcome the current crisis.
EFFESUS has been devised in order to reduce the environmental impact of Europe’s valuable urban heritage, by making significant improvements to its energy efficiency while preserving its cultural and historical values. The project develops and demonstrates, through case studies, a methodology for selecting and prioritising energy efficiency interventions based on existing as well as newly-developed cost-effective technologies and systems compatible with heritage values. This methodology is implemented in a Decision Support System, a set of tools and information models to facilitate an evidence-based diagnosis and decision-making.
District scale is the operational scale to deal with the implementation of energy improvements and their subsequent management, as the major potential is reached by the efficient use of resources. In order to optimise energy consumption and reduce CO2 emissions, strategies should be addressed at district scale, although the executive scale should be connected with the building and building component scales.
Historic cities can become a model of urban efficiency through the development of new strategies and analysis of existing information if the district and building scales are properly addressed and interconnected. The selection of actions suitable for each district depends upon the specific characteristics and restrictions of the historic district considered, along with the properties and limitations of the solutions proposed and the criteria that these actions will serve. Historic districts, as urban ecosystems, generate a large volume of heterogeneous information (at different scales, for a different use, of a different nature, from different tools and formats and from different stakeholders´ origin). The informational complexity of historic cities (due to their spatial, social and cultural richness, but also as result of their vulnerability) make them special beneficiaries of information management strategies. Since the energy management is an inter-scalar topic, strategies have to be multi-scalar. This is particularly relevant for historic environments, as it enables the identification of applicable strategies in protected buildings and landscapes. EFFESUS has addressed this challenge through a historic district categorisation methodology that enables the selection of building groups and representative buildings within the districts and a multiscale data model that structures all the necessary information for the decision-making process.
EFFESUS has researched and developed appropriate solutions for retrofitting historic buildings in European urban districts. The long-term objective is to achieve carbon neutral buildings and districts, for which it is necessary both to reduce the demand for energy and to maximize the amount of renewable energy supplied. Buildings which cannot be retrofitted due to their architectural and historical features will need more renewable energy to achieve carbon neutrality. This is possible with efficient district renewable energy systems, examples of which are available in the EFFESUS repository.
EFFESUS has developed a state of the art repository of energy efficiency measures and renewable energy technologies which are tried, tested and commercially available. This repository is combined with innovative software tools which can produce 3D mapping of urban districts and a Decision Support System to enable the analysis and development of effective retrofit strategies. Solutions must be appropriate for both the local climate and the heritage values of specific districts. The original design and construction of historic buildings limits the amount and type of energy efficiency retrofitting that can be achieved. However, modern services in these buildings can be made more energy efficient without impacting the heritage value with advanced sensors, controls and management systems. Upgrading the control systems to reduce the use of energy and ensure comfortable conditions is very cost effective. One of the most cost effective retrofitting strategies is retro-commissioning all the services so that they operate optimally. Changing people’s behaviour in the buildings can also be a no-cost measure, providing significant energy savings as well as improved comfort conditions for occupants and users. The Budapest case study uses a number of control strategies combined with innovative lighting and ventilation systems. Integrating renewable energy into a historic urban district may at first seem impossible due to the significant visual impact of many well-known technologies. However, for example, if renewable electricity can be made available from the local grid to power small scale heat pump systems hidden from view in roofs and basements, then power, heating, cooling and hot water can be generated very efficiently and cost effectively Alternatively, if bio-gas is produced locally from biomass waste, then the renewable bio-gas can be piped in a small bore network integrated into the streets during paving maintenance programmes. There are many creative solutions for historic buildings and urban districts which EFFESUS has identified, categorised, characterised and made available in the technical repositories.
In historic buildings, as in most existing buildings, the building envelope is crucial for their energy performance: walls are often thick, but they nevertheless conduct heat very well; single glazed windows lead to very low surface temperature, and are often not airtight at all. However, the criteria to be considered when selecting the appropriate retrofit measures go beyond the potential increase in energy performance; they also include the reversibility of the intervention, the possibility to conserve original material and, importantly, the aesthetic impact that a retrofit intervention might have. Within the EFFESUS project, several pioneering small and medium enterprises (SMEs) together with research partners have developed four innovative solutions to improve the envelope performance specifically in historic buildings: aerogel insulation, insulating mortar, radiant reflective coating, and upgraded original windows
The developed aerogel insulation is blown into the spaces, just a few centimetres in depth, of an existing wall structure – for example behind the “plaster on laths” finishing in Scottish tenement houses or wooden panelling in Alpine farm houses – thereby retaining the original surfaces and avoiding the loss of both original material and the evidence of traditional building techniques. Even the thin aerogel layer can reduce the heat transfer to about one third of the original wall, as has been shown both in the stone-wall prototype tested at INTENT lab and on-site in the Glasgow case study.
Appropriate for both the interior and exterior – and often uneven – surfaces of historic buildings is the formulated insulation mortar. Based on natural hydraulic lime (NHL5), it is compatible with most historic structures; the polystyrene insulation filler makes it both energetically and economically very interesting. It has successfully passed the driving rain and temperature stress tests and was examined outdoors in Holzkirchen and indoors in the case study building Benediktbeuern.
Interesting for historic buildings in hot climates is the radiant reflective coating. Thanks to the high infrared (IR) reflection it reduces the amount of solar heat absorbed by the envelope – be it the exterior wall or the roof – and thus reduces the cooling need within the building without intrusive impact on the building fabric. Even though the aim to get a both reversible and transparent product has not yet been achieved, the application simulations show what can be expected in future in terms of overall-year energy performance improvement.
For original windows, a number of improvement options ranging from thermal shading and low-emissivity films, to thin multilayered glazing, and the concept for a supply air window, have been investigated. They can be applied individually or in combination; for each window and building the right solution has to be selected taking a balanced account of all issues.
The tests of the products in laboratory and outdoor test-stands served both to demonstrate their durability and their actual performance in terms of contribution to reduced energy demand in different situations. The products were also applied at the different EFFESUS case studies, which allowed not only to measure actual on-site performance, but also to gain valuable experience on practical issues of applicability and ease of handling.
A major outcome of the EFFESUS project is the Decision Support System (DSS), an ecosystem of tools and methodologies to support evidence based diagnosis and decision-making, to identify and prioritise retrofit measures to improve the energy performance of historic districts. The project has developed a data model, a solutions repository, two software tools and a methodology that support the implementation of different processes within the framework. This web application uses information from the multiscale data model to perform a categorisation of the building stock and support the selection of representative buildings. A decision-making methodology has been developed and implemented in an expert system that guides the user in the selection of the best strategies for a historic district. Main target groups of the Decision Support System developed by EFFESUS are municipalities and urban managers responsible for improving the sustainability of historic districts and guiding the stakeholders in this process, as they usually coordinate the first phase of the retrofitting process on which EFFESUS is focused.
Different levels of decision-making have been established depending on the information availability and the stage of the process in order to maximise the application possibilities. The strategies are selected by using a multiscale heritage significance impact assessment method to estimate the applicability of the solutions, in combination with multi-criteria methods, to rank the strategies according to user preferences. Eventually the estimation of impact indicators at district level, to calculate energy demand and carbon emissions reduction, thermal comfort and indoor air quality improvement as well as the economic feasibility of the proposed solutions, are conducted.
While the focus in EFFESUS has been on the development of heritage-compatible technical innovations and the creation of a software-based Decision Support System, the project has also dealt with questions concerning how to overcome various non-technical barriers for energy interventions in historic urban districts. These kinds of barriers can be different in nature: namely financial, cultural, societal or political.
Financial barriers are closely related to the non-availability of appropriate funding schemes and public financial incentives to overcome the lack of financial capacity of house owners.
Cultural barriers exist, for example, in terms of contradictory understanding of architectural traditions and typologies of urban regeneration among the different stakeholders involved in these processes; while retrofitting of multi-occupancy house can be a societal challenge due to the often diverging interests of the various owners.
Political barriers can be the result of non-activity on the part of the municipal administration in energy planning and management of larger-scale urban retrofit measures.
Apart from these non-technical barriers, directly related to energy interventions in historic urban districts, EFFESUS has dealt with specific non-technical barriers with regard to the implementation of the project’s objectives.

Project Results:
The overall objective of EFFESUS was to develop and demonstrate a methodology for selecting and prioritizing energy efficiency interventions, based on existing and new cost-effective technologies and systems compatible with heritage values. The key project outcomes of EFFESUS include strategies for energy assessment, the analysis of existing solutions, the development of innovative solutions and a software-based Decision Support System.

1. European historic districts categorization and multiscale data model for the assessment and management of energy

As the EFFESUS project focuses on districts rather than individual buildings the district as a whole should be taken into account by identifying the interaction between buildings, the potential for common solutions and synergies. The district model needs a scale that is larger than the individual building scale to account for interactions between buildings For modelling the district as a whole one needs to take into account the following aspects: laws and regulations, climate, land use, shading effects and energy supply.
Building stock modelling is a tool for the planning and development of policies. For practical reasons, the investigation of a historic district as a whole cannot be made on a house by house basis. The building stock must somehow be reduced to a manageable number of categories that provide a satisfactory statistical representation of the whole stock.
The buildings selected to represent the whole building stock can either be sample buildings or archetype buildings. Sample buildings are actual buildings in a specific district. Archetype buildings are theoretically constructed buildings based on statistical data and field surveys. The archetype building can be constructed to better represent a segment of buildings within a building stock than would be possible by using only sample buildings. The definition of the data structure (the required information) and the categorisation (the processing of information) must go hand in hand. The categorisation method will define the need for data just as the availability and structure of data will set the limits for the categorization. In order to draw conclusions about energy saving on a district level for example, the results from the analysis of the typical buildings have to be extrapolated.
The scale of the district and the building stock will determine the method for data collection and modeling. On a national or European scale, statistical methods have to be used. On single well-defined districts, both data collection and categorisation can be more precise and can be adapted to local conditions.
The method to model the buildings in a district is based on a categorisation where the building stock is represented by a limited number of typical buildings. The selection of typical buildings is an intricate balance between the availability of data, accuracy, and the work needed to analyse the selected building types. In most cases we will need an iteration to find the right balance.
The overall process starts with the identification of available data, the definition of the minimum requirement of data needed, the assessment of data and the categorization, which provides a limited number of physical categories that represent the district.
Visby World Heritage City, a medieval Hanseatic city surrounded by a city wall and situated on the west coast of the island Gotland, has been used as a case study for developing the method of categorisation of building stocks within the EFFESUS project. Applying the categorisation method on the building stock of Visby results in eight categories of typical buildings. These typical buildings represent 94% of all buildings that can be modelled for energy assessment.

A strategy for information management for the sustainable renovation of historic district requires the definition of a common urban multiscale information model, which should be generic; interoperable with other data models and tools for management analysis as well as for decision-making, and containing semantic and geometric information.
In the EFFESUS project, this challenge is tackled with a multiscale information model based on CityGML, a standard data model. This model structures all the information of the district that is necessary for decision-making and management (geometric and semantic information) into a single iteroperable data model that integrates information from different fields and at different levels of detail. The model is based on international standards in order to make it interoperable with other data models and other tools (analysis tools, management tools, decision-making tools, etc ) and allow connection between Building Information Models (BIM) and Geographic Information System (GIS) models.
The multi-scalarity is one of the key properties of CityGML, since it supports different levels of detail. These levels are necessary to reflect the data collection of independent processes with different application requirements and facilitate the visualisation and analysis of data.
The multiscale information model has been implemented for the cities of Santiago de Compostela in Spain and Visby in Sweden. The data model has been constructed based on a methodology for semi-automatically build 3D-models using public domain data (cadaster, LIDAR data, available 3D-models, etc ). The CityGML standard is intended to be a universal model independent of the application domain. CityGML defines the most general types of objects and attributes that are included in the applications at urban scale. However, in order to fulfil the requirements of the EFFESUS project, it is necessary to define new elements or add attributes to the existing ones. For this purpose, CityGML defines the Application Domain Extension (ADE). Within the EFFESUS project, four specific extensions have been developed:
• Cultural Heritage domain extension
• Energy Performance domain extension
• Indicators extension, and
• Dynamic extension
The Cultural Heritage domain extension contains information on the cultural significance of historic districts, so that its retention can be ensured in the development of renovation strategies. The extension identifies character-defining elements, compatibility limits and requirements of heritage legislation. This data will be used as constraints in the decision-making process. If the data are sufficiently complete, this model extension will enable the Decision Support System developed in EFFESUS to disregard any retrofit measure which would cause damage to a district’s cultural significance.
The Energy Performance domain extension collates information at district, building and building component level, relating to the energy performance of a historic district. This allows estimating the energy performance of the buildings and the district
The Indicators extension represents a picture at a specific time. A picture may represent the real status or a simulated one. The indicator will store information about the situation before any intervention takes place and after one or several interventions, in order to monitor the results of the renovation strategy. The indicator extension includes indicators identified divided into four categories:
• Environmental conditions
• Embodied energy
• Operational energy, and
• Economic return
There is basic information that is constantly changing due to the influence of the building conditions, climate, season and use. The feature of representing temporal information to track changes, updates or interventions over time has been identified as a requirement of the EFFESUS data model. This dynamic extension includes all the data required for monitoring information, which changes frequently over time and is relevant for the assessment of the interventions carried out. Dynamic ADE includes information regarding indoor conditions and energy use, and for each of the parameters identified is stored the time and value of the measure.

2. Cost effective Technologies and Systems for improving energy efficiency of historic buildings and districts.

The EFFESUS repository is a web platform available at http://www dappolonia-innovation com/Effesus5/
At this link, any user can register in order to be allowed to navigate into the repository. Once registered and authenticated, the user can have access to the index page of the repository, which contains the links to five thematic sections and related data:
• Existing technologies for the retrofitting of historic buildings: technologies, systems and tools in use or near application for the energy retrofitting of historic buildings are listed, described and categorised.
• Existing technologies supplying renewable energy within historic districts: a registered user can consult the information regarding Renewable Energy Systems (RES) (1), Energy distribution systems (2), Energy storage devices (3) and Complementary tools (4). Each of these technologies is linked to the related indicators and a registered user can evaluate the assigned values against the indicators.
• Climate analysis - Passive retrofitting solutions: For each European climate zone, a registered user can visualise information regarding the regions that belong to the analysed climate zone, the passive strategies that can be implemented in such climate zone, and the main weather characteristics.
• Best Practices: a registered user can access the items on the identified best practices, downloadable in pdf format selecting the button “Best practices download”. Moreover, it is possible to visualise for each best practice some further information with reference to the European climate zone where the best practices were developed, and the typology of the applied technologies.
• Indicator List: The categorisation and list of indicators that have been used to evaluate the retrofitting solutions and RES technologies is reported as follows:
o Constraints: Impact on historic significance (Visual); Impact on historic significance (Physical); Impact on historic significance (Spatial)
o Habitability: Impact on thermal comfort; Impact on visual comfort; Impact on acoustic comfort; Impact on indoor air quality; Impact on electrical energy saving
o Economic feasibility: Cost
o Energy saving estimation, in terms of percentage reduction of the demand; Air change (winter); Window frame area; G-value; Shading factor; U-value walls; U-value roofs; Primary energy consumption / CO2 emissions

There are different options that can be used to establish suitable ways to balance building protection requirements with the need for optimised energy efficiency as well as to increase the share of renewable energies - from design to technology and materials and different levels of integration. There are many available strategies and technologies that can be applied to reduce energy demand and switch to sustainable energy solutions for historic buildings and districts. This requires close cooperation between experts who deal with historic buildings, energy efficiency and renewable energy systems.
The first step towards achieving energy savings together with the integration of renewable energies in an urban district is to undertake an analysis of the energy demand of every building. Demand analysis is a disaggregated, end-use based approach for modelling the requirements for final energy consumption in an area or district.
Secondly, allowing for the reality that a large number of technologies and technical solutions are potentially available for energy efficient interventions in historic cities, specific solutions must be selected on an individual bases, both at building and district level, in order to integrate them in a specific energy efficiency rehabilitation project.
As the third step, the renewable energy potential for historic districts has been examined. For this, solar energy, biomass, near surface geothermal energy, waste heat, wind, water and deep geothermal energy potential were examined, recognizing that local circumstances will influence decisions concerning the suitability of these different technologies. The architectural integration of renewable energy sources in a sensitive historic context or in historic buildings is very critical. It requires the study of the physical and the visual impacts of the technologies on the building as well as its surroundings. Particularly, it is necessary to define the design criteria for the equipment to protect the character and the appearance of the historic building and to take into account the reversibility of the intervention.
Another possibility and good solution is to integrate renewable energies using district heating systems. District heating and cooling systems consist of centralized heat or cold generation plants and piped networks to distribute the heat or cold to the consumers. District heating enables other technologies, such as combined heat and power, to realize its potential of lowering greenhouse gas emissions by recycling or reusing waste heat. Energy efficiency results not only through saving of fuel, but also in a consequent reduction of environmental pollution. Plants based on renewable energy systems (RES) have to be integrated in a useful way into the generation system. This relates in particular to the required energy output (heat/electricity: peak load and base load), available temperature level, performance class, logistic issues, integration capability and the location in the district heating network.
Energy use as well as energy production has always enjoyed a geographical correspondence. Energy production facilities can be located in the geographical context of a district and energy demands can be assigned to an area. The distance between demand and supply has to be bridged by transportation, which as well demands infrastructure that occupies space. The planning and optimisation of transportation lines and grids is very close to the original core tasks of geographical information systems (GIS) in mapping and cartography: avoiding unfavourable geographic conditions, long distances and disparities between demand and supply. Technical energy infrastructure, distribution grids and networks were part of the urban landscape as a matter of course and in its continuity they are hardly noticed anymore. Energy production sites were traditionally central large scale industrial facilities, with large local but marginal regional disturbance by visual appearance or pollutant emissions. With increasing shares of renewable energies inside cities and districts, the urban landscapes change. With the trend towards decentral production and the moving together of demand and supply, energy infrastructures become more visible because there are more scattered energy plants in the urban and open rural landscapes. At the same time the discussion on energy supply and efficiency becomes increasingly important. The visual impact of renewable energy plants and the trade-off between the new technologies and the well-known familiar appearance of urban and rural environments occasionally lead to severe public conflicts.
This can be moderated by visualization as well as processing of objective information through maps derived from GIS systems. Therefore a good data acquisition and documentation is fundamental for a good display of the investigated energy system in a GIS. Regarding the energy system, a three column structure should be followed: energy demand, energy production and energy supply infrastructure. To enable a holistic picture of the system in focus it is necessary to include some information from all the energy sectors including their demand profiles, the different energy sources as well as the potentials to use renewable energy sources. The objective is to identify all energy-related data bases and their spatial distribution on the considered area or district.

A comfortable indoor climate is a necessary condition for the use of any type of building. In historic buildings with poor insulation, high thermal mass and high air exchange, traditional temperature based climate controls may not be sufficient to provide both comfort and energy efficiency. In historic buildings, energy efficiency is not only about reducing energy consumption but also about improving the indoor environment. The core of the proposed solution is to control the indoor climate with respect to comfort indices. The target comfort levels of the different parameters are pre-set and then adjusted through user feedback. In addition, CO2 monitoring, scheduling of the set points of the parameters in function of the occupation planning, can be used for further improvements.
The proposed solution is based on the main principle that comfort should control the HVAC systems, not vice versa. The comfort is indicated by the percentage of persons dissatisfied (PPD), or predicted mean vote (PMV) criteria, and by user input. The calculation of the thermal comfort through the PMV or the Adaptive Comfort Model is made according to ISO 7730. In addition, to selecting the initial comfort levels, the user should be able to control the target comfort level continuously by a simple user interface. In order to keep the energy consumption down, it is necessary that this strategy is coupled with feedback to the users on energy and power consumption.
CO2 control can be a complement to the scheduling system. The scheduling system can set comfort criteria, and then the CO2 measurements can control the air exchanges. The same actions could be undertaken for an active and smart control management of Indoor Air Quality: the threshold limits of specifically selected pollutants should be included in the software that drives the ventilation system.
Weather forecasting and weather monitoring can be used to aid proactive indoor climate control allowing for reduced energy demand, lower peak power demand and improved comfort capitalizing on the high thermal mass of historic buildings.
Lighting control strategies provide additional cost-savings through real time pricing and load shedding. Lighting Management Systems (LMS) allow building operators to integrate lighting systems with other building services such as heating, cooling and ventilation, in order to achieve a global energy approach for the whole building. Several lighting control strategies exist to improve the energy efficiency.
Whereas in the past, ventilation was automatically linked to indoor air quality control, there is now a growing interest in ventilation as part of an energy efficient strategy for achieving thermal comfort in summer. Historic buildings were often more ventilated than strictly necessary because of loose-fitting doors, windows and other openings. In addition, open fires created generous rates of exhaust ventilation through chimneys at times when condensation risk might otherwise have been high. For this reason, historic buildings usually need more air conditioning and ventilation than modern ones. Nevertheless, if ventilation of a historic building is reduced too much through retrofitting initiatives, condensation, mould and fungal growth may occur, leading to deterioration of the fabric and contents, and possibly health problems will arise for occupants. Great care is therefore required in selecting an appropriate ventilation rate for a historic building. The energy consumption of ventilation systems is obtained as a function of air flow rate, pressure drop, efficiency and expected useful life. Energy savings can be achieved through targeted influence of each parameter. Active demand-controlled ventilation and air conditioning systems are helpful to measure and control all these parameters depending on the demand. Ventilation control strategies provide just the right amount of outside air that is needed by the occupants, dependent on conditions like air quality, temperature, and energy load.
A control algorithm is a mathematical or logical function that, based on the difference between a target condition and an actual condition, provides a signal to the Heating Ventilation and Air Conditioning (HVAC) system.
First, an initial comfort level is chosen, and then the user can give feedback to the Building Management System (BMS) to adjust the preferred level. If given comfort criteria are not fulfilled, the Building Management System will try to activate the actions from the energy ranking, always starting from the top. If the action improves the comfort, the action takes place, if the comfort level worsens, the action will not take place. The BMS follows the ranking until the comfort criteria are fulfilled. The weather control will override the comfort control when needed. Scheduling will also override the basic comfort control by setting new target levels when the room/building is not in use.
As far as CO2 and pollutants are concerned, in conditions where the sensors measure values close to or above the threshold limits, the ventilation rate must be increased; in the opposite case, when the contaminant level decreases, the ventilation rate must be reduced to the minimum background air change level for that type of space.
Algorithms for illumination control are essentially based on two strategies: occupancy control and daylight harvesting. Occupancy sensors drive the lighting controllers in an on/off mode. Sometimes a minimum lighting level is maintained for safety reasons. Also a timer is sometimes included to avoid lights being unduly switched off when the occupancy sensor does not sense any movement.
Strategies for energy conservation in HVAC systems are usually directly integrated into the control systems of the HVAC systems. The algorithms differ in function of the HVAC system itself and the strategy selected. The chosen control strategies of respectively indoor air quality (IAQ), thermal comfort, illumination and HVAC finally need to be integrated in a Building Management System. Interactions between the respective controllers can become very complex and priorities will need to be established to manage the whole set up.

The current challenge is to reduce the environmental impact of windows by retrofitting them with energy efficiency measures without compromising their cultural and historical values. Windows in heritage buildings present a particular challenge as they were usually made with decorative timber profiles and single glazing, and it is often expensive to replicate their design and improve their performance without compromising their heritage value.
In the initial stage of developing the window solutions, numerical modelling was used to predict the performance of the prototypes. In order for the results to be comparable and reliable, several computation standards were reviewed. It was decided to use more than one standard of numerical simulation in order to give the best information about the investigated options. The application of each improvement option has been tested and investigated using a box-type original window as a starting point. Application of each solution to the base window resulted in five different prototypes:
Prototype 0 – “Original Window”: is a typical box-type window, consisting of two sashes separated by a 12cm wide air gap. It represents a significant advance in thermal comfort and insulation from previous windows with only a single piece of glass separating the interior from the exterior environment.
Prototype 1 – “Thermal Shades”: includes thermal shades installed in the air gap between the glass layers in the box window. Thermal shades in this case are cellular shades (type: “cell in cell”), which adds thermal resistance to the window and reduces solar heat gain in the summer.
Prototype 2 – “Adhesive low-emissivity films”: uses adhesive plastic films with low emissivity properties. The advantage of this solution over low emissivity coatings on the glass surface is that those films can be added to the existing glass, while low emissivity coatings can only be applied during the manufacturing process.
Prototype 3 – “Multi-layered glazing”: uses insulated glazing units which include thin glass panes (glass thickness from 0 1 to 1 mm) in a multi-layered unit. Ultra-thin glass panes are used as the middle panes in a multi-layered glazed unit. This provides high insulation levels while keeping the overall unit light-weight and narrow. In some cases this allows the original design of the historic window (and frame) to be preserved while providing a substantial thermal improvement.
Prototype 4 – “Air Sandwich”: integrates a product called the “Air Sandwich”, which consists of five transparent thin plastic layers glued to the original panes with plastic frames sealed with a secondary sealant. Increased thermal resistance of the air sandwich is due to multiple air gaps, which are created by thin plastic layers. Each air gap adds additional resistance by splitting air into small volumes and limiting size of convection loops. Moreover, multiple layers of material reduce radiation heat exchange – providing better thermal performance.
Prototype 5 – “Supply Air Window”: uses specially designed valves which allows fresh air to flow from outside to inside in the designed gap between two panes of glazing (air is driven by exhaust fan installed in the room). As it flows from the bottom of the window to the top it recovers heat that is flowing through the glass towards the outside. The fresh incoming air is heated during its passage between the two panes of glass before entering the building, through convection and conduction in the cavity. This creates a high performance window, which U-value is dependent on the environment conditions. If the window happens to receive direct solar radiation it also acts as an air solar collector, but this is not its primary operating mode.
It should be noted that the presented technologies can be used together in one window in order to improve its thermal performance. Several combinations have been considered and investigated.
In order to compare performance improvements a Prototype 0, which represents the original, the unchanged box-type-window was used as a baseline. The improvement options influence the original windows in different ways. Prototype 3 (incorporating ultra-thin glazing) has the lowest thermal transmittance; however, installation of the insulated glazing unit may require some changes to the original window structure and is labour and cost intensive. The Air Sandwich product is easy to install in an existing window and provides some improvement in the thermal performance, however the visual appearance of the product may not be acceptable. Installing thermal shades and adhesive low-emissivity films provide some thermal improvements but may have unacceptable visual impacts. Both technologies are relatively easy to install, and the shade may also reduce glare problems, provide privacy, and reduce solar gain.
All of these strategies can be enhanced with supply air window valves which can improve thermal performance and indoor air quality if properly designed. There is a wide range of building types with historical value in most historic urban districts, so we have investigated a number of options for window improvement which may be adapted to different types of windows. For each window and building, a specific solution should be selected which takes a balanced account of all the issues including historical value, reversibility of the change, visual appearance, thermal performance, moisture performance, indoor air quality, cost, maintenance, and durability.
It is a challenge to achieve a balanced solution for improving windows in a cultural heritage building, but we need to develop acceptable solutions given that these buildings are a significant part of Europe’s building stock. Thermal and daylight simulations were conducted for several window configurations in order to find the most efficient solution for the EFFESUS case study in Budapest. Since two windows were replaced, for each we used slightly different configurations for testing purpose. The first window incorporated three layer ultra-thin glazing; the second, a two layer standard unit in inner sash. Both windows were equipped with electrically controlled shades and ventilation valves.

The majority of the building stock from before 1900 was erected with natural hydraulic lime-based mortars in solid masonry. Due to the low modulus of elasticity of lime-based mortars, there has never been a need for dilation joints in old masonry structures. Changes in shape as a result of expansion and contraction, due to hot/cold cycles, could be “followed” by these masonry structures without damage. Moreover, lime-based mortars have a high vapour transmission rate, beneficial to the breathing capacity of monolithic historic masonry. These two most important characteristics have been taken into account when selecting the binder in EFFESUS.
ISOCAL is an insulating render, designed and developed for use on masonry in cultural heritage buildings as well as for retrofitting of historic urban districts. It is a natural hydraulic lime NHL5. This specific quality of lime allows the render to be used for inside as well as outside applications due to its resistance against mechanical and environmental influences. The selected aggregates, fillers and additives not only provide a low lambda-value, a high vapour transmission rate and good mechanical characteristics, but are also compatible with historic mineral substrates. ISOCAL can be applied by any skilled plasterer.
For the development within EFFESUS project, Bofimex selected a NHL5 lime. Several insulating fillers were reviewed and checked for their suitability. Finally, it was decided to rely on Expanded Polystyrene (EPS) as a well-known insulating agent in buildings. It has the advantage of an easy use in mortar formulation together with a good cohesion/coherence with the mortar binder, and the product is broadly available on a commercial scale with corresponding low product costs. The new mortar formulation was processed and tuned in a way that it has a good workability and applicability.
Because of its composition based on NHL binder and a layer thickness of 3 cm or more, this base mortar layer requires a longer drying time (approx. seven days) before finishing layers can be applied. The mortar is applied in situ as an uninterrupted skin on the substrate, thus eliminating thermal bridges.
Like all insulating renders, ISOCAL cannot remain visually exposed for physical and aesthetical reasons ISOCAL should receive a finishing plaster at least seven days after application. This finishing not only provides the render with an acceptable aesthetical appearance and a good weather protection, it also improves the impact strength of the total system.
The experimental campaign carried out within EFFESUS allowed to develop a technical data sheet with all relevant product characteristics. Besides, the technical durability of the ISOCAL plaster system was determined in an EOTA (European Organisation for Technical Approvals) test wall chamber based on the assessment procedures for External Thermal Insulation Composite System (ETICS), according to European Technical Approval Guidelines (ETAG004). This was accompanied by a field test under real climate conditions at Holzkirchen in Germany. In both procedures the ISOCAL proved to be durable with sufficient bonding, cohesion and weather resistance. The lambda value of 0,0682 W/(mK) is better than the ones known for standard (lime-based) plaster materials.
To prove its contribution to the energy performance of historic buildings, the mortar system was applied in a case study. The building selected for that, named “Alte Schäfflerei”, is dated from around 1760 and part of the craftsmen court of the monastery in Benediktbeuern. For the specific demonstration within the EFFESUS project, one room on the ground floor in the northern part of the building was selected. In order to evaluate thermal performance of the new insulating mortar, the data recorded before the intervention were compared with the ones collected after the application of the mortar.
The thermal insulation of ISOCAL mortar was proved by the monitoring data recorded in Benediktbeuern, in particular by: the higher difference between external and internal wall surface temperatures, the decrease of the heat flux, and consequently of the conductance and transmittance of the insulated wall, the improvement of the indoor comfort, as well as the reduction of electrical demand and peak load needed for heating.

The A Proctor Group Ltd have developed Spacefill, a unique, thin, highly efficient insulation for use in historic buildings with existing solid wall construction where lath and plaster finishes are present. The ability to insert high performance insulation into an existing cavity is highly attractive due to the fact that the removal of the lath and plaster is expensive, disruptive to the homeowner and can also mean the removal of decorative plasterwork such as cornices etc.
Spacefill utilises this empty space between the masonry wall and plaster finish, so does not encroach on valuable room space. As it uses existing installation methods, this is also relatively simple, with minimal redecoration required. This would be a major advantage to the homeowner.
Spacefill is derived from aerogel insulation which has a class leading thermal conductivity, but is also breathable and water resistant – all properties which are ideal for cavity insulation. Ways in which to install this insulation using existing blowing in techniques and equipment have been researched. Various cutting trials were carried out on the raw material in order to achieve a suitable size which could be used.
Testing was carried out to determine the thermal conductivity of the Spacefill at a specific density. The optimum density was found to be 70kg/m3 and produced a thermal conductivity of 0.0255W(mK).
A yearlong trial of the Spacefill has been carried out in Glasgow, where a property has been taken over to conduct the trial. This property is a second storey, mid-terraced tenement in the Yoker area of Glasgow. The external wall is of sandstone construction, which is typical of historic buildings in this area. This was identified as ideal for the retrofitting of the Spacefill blown-in insulation.
The aim was to fill the cavity behind the plasterboard/lath and plaster in one room and then be able to compare the thermal performance between the uninsulated room and the insulated room.
On-site trials have proved successful in terms of installation, and the installer has commented that Spacefill was the best insulation they have used to fill a cavity – better than bead, foam or fibre. There was dust generation; however, this was only evident on the external wall side and there was very little dust generated on the room side. Monitoring equipment was installed and data collected over the entire year. At the time of removal, thermal comfort readings as well as thermal imaging were taken in both rooms. This indicated that the cavity has been well filled.

Radiant reflective coating, without intrusive impact on the building fabric, can improve the envelope performance. EFFESUS aimed therefore at developing a coating with high Infrared (IR) reflection, which reduces the amount of solar heat absorbed by the envelope – be it the exterior wall or the roof – and thus cuts the cooling needs within the building.
The chemical nature of a coating depends mainly on the specific needs of the substrates on to which it will be applied and on the desired durability of the coating. Thus, in order to design a suitable new coating from the point of view of its ideal properties, firstly, a selection of four targeted substrates was made. Amongst the most common building materials of European Cultural Heritage there are sandstones, limestones, bricks, travertines, granites, marbles and mortars. The aim was to select materials with a variety of porosity and pore size values. Two building stone typologies were selected together with brick and lime mortar.
Once substrates were characterized, a selection of best-selling commercial additives, mainly based on ceramic spheres and nanoparticles taking into account the final application of IR reflecting properties, was made.
Two different coatings, namely as Coating 1 and Coating 2, were synthetized by the project partners ACCIONA Infrastructures and Advanced Management Solutions Ltd (AMS) using two different approaches: Coating 1 was an inorganic coating fabricated using the sol-gel method and Coating 2 was based on a water base solution.
Sol-gel reaction scheme is based on hydrolysis of various alkoxides forming respective silanols. This is followed by a condensation reaction occurring between silanols or between silanols and alkoxides. The sol-gel process involves evolution of inorganic networks through the formation of a colloidal suspension (sol) not alter the original condition of the substrate. The most important advantage of sol-gel processing over conventional coating methods is the ability to precisely control the microstructure of the deposited film. Different sol-gel coatings were obtained by means of incorporating one (or some) of the nanoparticles and additives.
In the case of Coating 2, different formulations were also developed, mostly based on ITO in various granularities and concentrations. In order to ensure the reversibility of the IR reflective system, a reversible primer was applied as base coat prior to the addition of the top coat IR reflective coating. After testing and evaluating different candidate primers widely used in historic buildings, Paraloid B87 was selected.
As a result of the experimental work and the testing campaign, two new IR reflective coatings were obtained:
• Reversible, IR reflective coating for all substrates tested, but non-transparent
• Transparent, reversible and IR reflective coating for lime mortar and metal
Both coatings showed excellent results regarding the hygric properties (capillary water absorption, absorption at atmospheric pressure, water vapour permeability) and durability.
It was agreed, firstly, to assess and determine the thermal performance of the first coating applied on a large scale wall in a guarded hot box called INTENT (Integrated Envelope Testing facility), and secondly, to demonstrate the second coating in a real building in Istanbul. The intervention consisted of the application of the coatings on different substrates placed on a parapet wall at the top of the building. The coatings were not applied directly on the facade of the building as their removal, on such a porous stone, could at this stage not be guaranteed. Furthermore the monitoring of the energy performance on wall and room level would have been difficult, considering the influence of very large window areas of the case study building and the difficulty to impose equivalent user behaviour in different rooms.

3. Development of a methodology and tool to assess on energy retrofitting interventions in historic cities
The EFFESUS Decision Support System (DSS) is an innovative system for the assessment of energy-related interventions in built cultural heritage at building and district level. It supports users to select and prioritise energy interventions with full respect to the historical significance of the buildings.
Four Levels of Decision Making (LoDM) have been defined, relating to four different levels of information availability:
• No information: the user could just access generic information (Level 0)
• Low level: the information will be provided by the user through questions defined by the transferable models, based on the European building stock categorisation. No data model will be used (Level I)
• Medium level: The multiscale data model will be used at this level, but only with a low level of detail. This information will be sufficient for the categorisation tool, in order to identify building typologies within the historic district and “sample buildings” that represent those typologies. A more complete information regarding these buildings in the data model will allow the user to obtain results that could be extrapolated to the entire category and consequently to the whole district according to their level of representation (Level II)
• High level: when the data model has complete information regarding a high percentage of the buildings of the district (Level III).
To support professionals in the strategic decision-making processes for retrofitting historic urban districts, the expert system developed in EFFESUS requires two types of data inputs: location-specific data about the district, and technical data about available retrofit measures and associated assessment indicators. The data of retrofit measures are not location-specific and are stored in the technical repository. As the availability, completeness and quality of district data can vary significantly, the DSS has been developed so that it can perform assessments at four different detail levels, as explained above. The district data inputs will obviously have a significant impact on the outputs the DSS can deliver.
Where hardly any suitable district data is available, the DSS will base its assessment solely on the geographic location of the districts (Level 0 assessments). In this case, the outputs of the DSS will be basic information about building retrofits suitable for the climatic region in which the district is located. Where the software user is able to provide at least some minimum information about the district, a level 1 assessment can be performed, by assigning a district type to the district and comparing it against standard typologies saved in a transferable model together with suitable retrofit guidance. In this case, the DSS output is based on the district’s climatic region and its typology. The DSS will guide its users through a set of questions, selecting the parameters which are required to allow the identification of the district type. For both level 0 and level 1 assessments, no district data model is required.
Only where sufficient data is available to generate a data model, the more advanced assessments of detail levels 2 and 3 can be performed by the DSS. Where datasets are of little completeness, a level 2 assessment will be used, based on an analysis of the building stock using the Building Stock Categorisation Tool. Thereby, the district will be reduced to a suitable small number of typical buildings, for which sufficient data is either already available or can be obtained reasonably easy. The DSS assessment will base its assessment on these typical buildings and extrapolate its results to the whole district. Only where complete or near complete district datasets are available, a level 3 assessment be conducted. In this assessment case, the DSS uses data straight from the multiscale spatial district data model. These assessments will be the most detailed and reliable ones, but will also be the most resource consuming, particularly with regard to the identification and preparation of the district input data.
For level 2 and 3 assessments, the DSS will analyse the impact of the various retrofit measures catalogued in the Technical Repository as if they were to be installed in the district. The impacts will be assessed using the indicators listed in the repository, with regard to economic return, energy consumption (embodied and operational), indoor environment, heritage significance, and technical compatibility. The latter two assessment aspects are implemented in the DSS as constraints to filter out retrofit measures which are considered as unsuitable, regardless of the outcome of the other assessment aspects. The assessment process will identify, for each assessment aspect, those retrofit measures which are the most suitable for a specific district. In a final step, the DSS will combine the identified measures into recommended packages of retrofit measures, for further investigation by professionals to confirm their suitability in specific building cases.
To make the DSS more interactive, users can set strategic priorities, for example by identifying and balancing capital expenditure against anticipated savings in energy or carbon emissions, or by identifying improvements of the indoor environment. To sum up, the inputs from the data model and the technical repository are used by the DSS to produce.
• A current state regarding energy demand and carbon emissions
• A list of possible solutions classified by their applicability
• A priority list of packages of retrofit measures which are likely to be suitable in the context of a specific historic district.
The homepage of the DSS provides general information about the system to urban planners or other stakeholders. Users can read further information about the EFFESUS project (innovations, outcomes), the DSS, European national policies regarding energy and cultural heritage, best practices, etc. Users can register or login to the Decision Support System. It is important to note that only registered users can create or edit their own projects.
Registered users are able to manage their existing projects or create new ones. Utilising the user-friendly interface, users can exploit the numerous functionalities that the system offers to manage their projects. Specifically, the user can create, open, edit and change the settings of a project and delete it. Depending on the type of the project (Level 1 or Level 2) which the user attempts to open, the forms Level 1 (LoDMI – Questionnaire) and Level 2 (LoDMII - All Buildings) are displayed correspondingly. The collaboration tool enables a user to upload and store significant documents and to share it with other users. Additionally, users can establish links to communicate with other users via a wide range of means.
The software tools were tested regarding their functionality, user-friendliness and suitability. The aspects tested included energy and economy (including carbon dioxide emission and financial costs), suitability in a historic context (including cultural significance and material compatibility) and environment impacts (on indoor and outdoor environments). Firstly, the DSS web portal was reviewed and suggestions made for improvements to its layout and content. This included a general review regarding the usefulness of the information planned for dissemination as DSS outputs where no suitable district data is available. Secondly, level 1 assessments were tested using the cities of Santiago de Compostela in north-western Spain, and Visby in south-eastern Sweden at the island of Gotland.
Lastly, level 2 assessments were performed. The identified sample buildings were tested by using them in the DSS and analysing the resulting data outputs. The software, firstly, generates a list of retrofit measures, which it considers applicable in the particular location-specific context. This list was found to be generally suitable. The identified measures were then ranked manually and allow software users to set priorities regarding indoor air quality, disruption, thermal comfort, energy saving and associated costs. The ranked priority lists of retrofit measures were found to produce suitable results; the associated quantitative calculations (including energy consumption, savings, costs) were plausible.

Potential Impact:
Citizens’ engagement strategies
One of the main challenges with regard to the management of historic centres is to encourage the active participation of the inhabitants living in these areas. Focusing on energy rehabilitation is one of the best ways to boost participation, as it directly affects citizens and the living conditions of the buildings in which they live.
Owners are responsible for ensuring the proper conservation of their buildings, and energy efficiency and maintenance programmes require their participation. Retrofitting from the energy point of view can be an opportunity to involve citizens in complex urban regeneration processes, as it requires the commitment of residents to directly undertake rehabilitation mechanisms in order to maintain their homes.
One of the tasks of EFFESUS was to promote an energy workshop for the inhabitants of the historic centre of Santiago de Compostela. This workshop has been organized by the Consorcio de Santiago with the objective of setting up an “Urban Energy Laboratory” in the historic city centre. The Consorcio de Santiago has been stimulating various rehabilitation programmes during the last 20 years with great acceptance among the inhabitants, and it will now develop a programme to advise citizens on the energy characteristics of their buildings and homes. This laboratory will give advice on possible energy solutions for each individual dwelling, through the exchange of information between professionals and inhabitants interested in innovative results.
In addition to assisting citizens in energy rehabilitation, the Urban Energy Laboratory will contribute to improving knowledge on how buildings are used, managed and transformed to meet modern comfort requirements, as well as to collecting information on energy consumption and housing environmental management strategies. The laboratory will also foster key knowledge for visitors, by explaining and illustrating options for how to handle the permanent transformation processes in historic centres without endangering the urban heritage values they represent.
Against this background, what are the appropriate steps for changing and improving living standards without damaging heritage values? In our opinion, the response can be related to energy and to the culture of maintenance, on the capacity of the buildings to allow changes easily, and the ability to create jobs and boost the local economy through the processes of urban transformation.
There is a clear parallel between the loss of heritage and the loss of energy values, as traditional living models and architectural and urban features were adapted to the environment. Instead of rehabilitation, it seems advantageous to talk about liveability. Energy and preventative maintenance for the preservation of the historic city can only be managed from the active involvement of users. Therefore, it is necessary to engage citizens in the preservation of heritage and to replace the culture of dependence by a culture of commitment.
If we admit that a city is continuously changing, we should consider urban rehabilitation as a process which has to respect the rhythm and continuity of this state of permanent transformation. Hence, in historic cities, even apart from their heritage values, methodologies for intervention must necessarily be tempered to the daily reality of the city and its inhabitants in order to be adapted to this complex scenario of continuous change. It is not easy, but this is the real challenge of urban regeneration.
Within the framework of the policies of urban regeneration that drive the Consorcio de Santiago, and in coordination with the actions planned in EFFESUS, the Urban Energy Laboratory and workshop “Refurbish With Energy!” was held for a week with the involvement of the inhabitants of the city who feel committed to the intelligent management of energy in their homes. In parallel with the citizen workshop, the children’s workshops “Learn & Play With Energy Efficiency!” was held, to the purpose of involving the young inhabitants of the city in something that will be decisive in their lives.
The experience of the method of citizens’ participation and engagement in the city of Santiago de Compostela and the creation of the Urban Energy Laboratory can be considered as a good practice, replicable in other historic cities, willing to promote the culture of maintenance and energy efficiency solutions.
Non-technical barriers to retrofitting Historic buildings and urban districts in Scotland
Novel and adapted retrofit products make it possible to improve the energy performance of historic buildings in ways that are sustainable and have no adverse impact on the characteristics that constitute their cultural importance. Some limitations, however, remain: Inappropriate retrofits can cause accelerated deterioration of building materials, create harmful indoor environments and reduce a building‘s cultural significance. Despite this, appropriate retrofit measures are now often available to choose from when retrofitting a historic building. Yet, their uptake is slow. Often, it is not only technical barriers that hinder a building’s retrofit, but non-technical barriers of financial, cultural, societal or political nature.
The overview will concentrate on Scotland, but some of the discussion will be applicable to the other parts of the United Kingdom of Great Britain and Northern Ireland (UK); and many issues discussed will also be transferable to other places in Europe.
With regard to financial barriers, the UK tax system incentivises the construction of new residential property over the improvement of existing buildings. The tax system incentivises energy performance improvements but favours even more new construction and building replacement. Furthermore, to date, the energy performance of properties does not influence property prices significantly, although it is mandatory to provide EPCs when letting or selling residential properties. In Scotland, prices are still predominantly determined by location and number of bedrooms. This lack of influence of a property’s energy performance on its prices is a disincentive to making energy-related improvements. Furthermore, EPCs for residential properties are calculated with RdSAP, which does not provide realistic assessments of the in-use energy consumption of older buildings.
Apart from the financial aspects, various cultural barriers exist, many of which relate to the multiple ownership of buildings. Scotland does not have mandatory forms of associations of the owners of a tenement. In Germany, for example, property owners are legally obliged to establish residential property owners associations to deal with common building maintenance. In Sweden, tenant-owner associations are not uncommon for buildings which are owned jointly by occupiers. As part of the German or Swedish systems, owners are generally required to make regular payments into a common fund in order to cover the costs of on-going building maintenance and future repairs. Such communal systems can then also be used for joint investments into energy performance improvements. The general absence in Scotland of such forward-looking owners’ associations means that routine building maintenance and repair are difficult to organise; joint energy performance improvements are even more difficult. Yet, carrying out works collectively often reduces capital costs (for example: scaffolding is only needed once if works to a façade are carried out jointly), and many improvement measures only become feasible when installed and used communally (particularly systems for energy generation from low-carbon or renewable sources, such as heat pumps or solar panels).
Retrofit issues also arise from the often diverging interests of the owners of buildings in multiple ownership. The owners are rarely a homogeneous group, but a mix of owner-occupiers and short- and long-lease landlords, and of different age groups and household forms (for example: couples, families, flatshares, widowers). The owners have often different and opposing interests on how to develop their properties, and energy performance improvements are not necessarily an investment priority. Young property owners, for example, might not plan to stay in the property for long enough to make retrofit measures financially viable, particularly those requiring high capital investment and with long payback periods. The same is true for elderly owners, as their often reduced income and remaining life expectancy might make long-term investments not worthwhile. Landlords, generally, have little incentive to invest in energy performance improvements of their properties, as this will not save them money; the energy savings will only benefit their tenants. It remains to be seen to which degree forthcoming UK regulations requiring minimum EPC ratings for the rental and sale of residential properties will act as an incentive for owners and developers to invest in energy performance improvements.
Communal installation of retrofit measures at a building scale makes options available which would not be feasible for singular flat owners. The same is also true at higher scales: Joint retrofits on a neighbourhood or urban district level allow the installation of energy-related systems that are not possible at the scale of single buildings, such as combined heat and power (CHP) plants and district heating systems. The latter is, for example, used in the historic city centre of Visby, a UNESCO World Heritage Site on the Swedish island of Gotland, where a distribution network was installed below the centre‘s street surfaces.
Initiatives of this scale are rare in urban Scotland. With regard to CHP plants, for example, only few have so far been installed, mostly at university and sports campuses. The University of Edinburgh, for example, powers its Edinburgh campuses with four CHP plants, feeding a district heating system which, however, remains disconnected from the adjacent historic city. A rare example for urban-scale retrofit in Scotland is the installation by Cube Housing Association in 2012 of a district heating system with CHP plant at the mid-20th century Wyndford Housing Estate in Glasgow, serving nearly 2000 homes in three-storey terraced buildings and fifteen-storey high-rise towers. The installation of Visby’s district heating system was greatly supported by the Government of Gotland Region. It seems that, unless Scotland’s public administrations start taking a more active role in energy planning and management also, such larger-scale urban retrofits will not become commonplace in Scotland.
Market implementation of EFFESUS innovations
A successful energy-efficient retrofit of a historic urban district is a process which requires the stamina of all stakeholders, as success can only be achieved with the cooperation of public authorities, private enterprises, private owners, investors and residents. With this knowledge, EFFESUS initiated several activities dedicated to overcoming some of the major implementation barriers which arise in multi-disciplinary retrofit projects. These efforts focused both on facilitating the conduct and coordination of the project activities in the seven case studies and on the potential market implementation of the heritage-compatible innovations developed in the project.
The project outcomes show that the number of implementation barriers correspond to the complexity of the interventions that were undertaken in the seven EFFESUS case studies. The project partners responsible for implementing interventions on the district level had to deal with the quite different expectations and interests of various stakeholders. As research in this area has consistently shown, most people are not motivated by the concepts of ‘energy efficiency’ or ‘sustainability’. Most people need to understand that they will have more direct benefits before they will engage with concepts which are perceived as only having an indirect or general impact on them.
One tool to address this challenge is to offer showcases, where citizens can test the living conditions in historic buildings following the introduction of innovative technologies. Moreover, it has been concluded during the case study implementation that there is often a lack of good and neutral information, and citizens are not well informed about how much energy they use. To improve this knowledge, charts and other visual summaries of the typical energy use in an average household in their historic district over some years would be very helpful. Moreover, reliable information from a trusted and independent source on the investment and maintenance costs of selected technologies, together with information on the expected savings due to reduced energy use, is necessary in order to convince people to make changes and investments.
Another important challenge for working on a district level are the local administrative procedures, which are often slower than expected. Hence, the involvement of the local administration from the very beginning is of utmost importance, as one should not underestimate the time for building trust with a local administration for such activities.
Although the project has involved stakeholders at an early stage for the case studies, the main recommendation for overcoming the barriers to implementation is to involve the local administration, heritage authorities and property owners at an even earlier stage to achieve the necessary permissions for retrofit interventions. In most cases, their involvement at least a year before the planned interventions is necessary. The activities of building trust and exchanging information with the local authorities and building management have to be continuous to achieve success, including beyond the completion of individual projects.
In order to market the heritage-compatible innovations developed within the EFFESUS project, the following considerations are considered crucial:
• Development by companies of market-specific business models for their new products
• Recognition that market prediction and turnover estimates for new products are not easy
• Anticipate internationalisation of the business model to expand the market potential
As mentioned above, it is often difficult to convince citizens to change their current energy systems and to implement measures to improve energy efficiency. People may say that they want to protect the environment, but real decisions are influenced by other criteria, for example to increase the value of their property, to save money, or to increase their comfort levels. For this, market-specific business models have to be developed.
A useful methodology to develop new business models is to use the Osterwalder “Business Model Canvas”, which supports the creation of numerous new models in a short time. In this way, more than one model can be developed and different ideas discussed, a necessity in order to explore and understand the full market potential of any new product.
It is difficult to make market predictions when entering a market with a new product, and especially to estimate turnover. Therefore, it is necessary to conduct a deep market analysis first. For this, data about the total number, the age and the status of the historic buildings of the target market are needed. Given this information, it is possible to estimate the market share and the quantity of sales; the price for the products must also be established. For this it is necessary to know the internal cost of production (direct costs, fixed costs, profit margin). Producers also have to consider that there is a market price, namely the price customers pay for similar existing products. Because there are assumptions in the calculation and the input data have uncertainties, it is reasonable to calculate different scenarios of financial analysis. In this, it is important to keep in mind that the aim of the calculation is not the prediction of the future, but the analysis of whether a business model is realistic.
Inherent in the innovation and uniqueness of new products is the opportunity for producers to enter international markets to increase their sales. Some challenges are connected with this decision, including language, different rules and legislation, new market awareness, and funding for investment. Solutions can be found through hiring management staff with specific knowledge of a target country´s culture and its language; and more effectively, where a partner can be identified in the market the company wants to do business. International networking is essential for all sizes of business, including small and medium-sized enterprises (SMEs).
Dissemination activities
Since the beginning of the project, different activities concerning dissemination were planned and carried out, in order to make the broad field of conservation professionals, industry and owners aware of the project results. The EFFESUS website was launched on the internet at a very early stage of the project and it was continuously updated. Moreover, leaflets, newsletter and posters were produced and distributed within the national networks of the consortium partners and at national and international conferences, workshops and fairs. A booklet comprising key project results was distributed via the project website and through the scientific networks of the consortium members, fostering dissemination of the project targets and results achieved.
Training courses aiming at integrating energy issues in the education of relevant professional groups taking part in the planning and implementation of conservation and improvement in historic urban districts, were organised: a pilot course carried out in Visby during spring semester 2015, a post-graduate summer school in Venice in December 2015 and a pilot implementation which has partly been carried out at the Fraunhofer-Centre in Benediktbeuern. Furthermore, three international symposia have been held in Munich (Germany), Ferrara (Italy) and Anglet (France). Finally, at the end of the project an international conference was organized and a video produced.
The exploitation plan was outlined and actions were agreed among the partners in order to ensure the adequate commercial exploitation of the results of EFFESUS. The exploitable results of the project are the improvement of the existing technologies, the development of new materials and solutions together with the main outcome of the project, the Decision Support System.
In order to support the exploitation plans, the possible exploitation routes of the developed technologies were elaborated: partners defined their own individual exploitation routes of the different results generated within the project taking into account their individual possibilities, resources and needs.
The documentation of the results of EFFESUS contains a short description of results together with the technology readiness level. The statement of ownership of the specific result was determined since the participant beneficiaries are the owners of the result. The participant partners specified the proportion of work done during the task. The ownership is based on the participation in the definition and in the implementation/demonstration. An assessment of the socio-economic impact of the technology was carried out. The target groups of exploitation activities and the advertising possibilities were collected for each result. The innovation partners analysed the possible contribution to any standard and the Intellectual Property Right.

List of Websites:
Website address:

Project Coordinator:
TECNALIA Research & Innovation
Dr. Isabel Rodríguez-Maribona,
E-mail: isabel.rodriguez-maribona

Scientific and Technical Coordinator:
Fraunhofer-Institute for Building Physics IBP
Prof. Dr. Gunnar Grün, FRAUNHOFER
E-mail: gunnar.gruen