Smart façade for energy-efficient buildings
Much of the European building stock needs renovation. A large share of the suburban multi-storey residential building stock was built in the 1960s-1970s, at a time when environmental standards were much lower and little or no consideration was given to sustainability. As a result, these buildings have high energy consumption, low air quality due to poor ventilation, and low architectural value. The E2VENT project has taken up the challenge to improve energy-inefficient buildings to meet modern green standards. It sought to achieve this by implementing innovative sustainability-enhancing technologies and solutions for the exterior of older buildings, delivering efficiency benefits for owners and tenants alike. Combining comfort and lower energy consumption Project partners unveiled a smart modular heat recovery ventilation (SMHRV) unit which improves climate control, whilst promoting efficient energy use and limiting thermal losses. “The E2VENT system is a façade refurbishment solution with external cladding and air cavity that embeds different breakthrough technologies that should enhance thermal performance and indoor air quality,” notes Dr Antoine Dugué. The smart unit allows heat recovery from the extracted air using a thin double flux exchanger. In winter, it preheats the fresh air coming from outside before reaching the living spaces, whilst in summer it precools it. Additionally, instead of having a fixed air flow it uses the measured internal CO2 level to blow the adequate new air, allowing optimal air renewal: air renovation when needed and with recovered heat. It is also made from aluminium to be light. “We expect our heat recovery unit to reach an efficiency of approximately 80 %,” notes Dr Dugué. Another innovation demonstrated by E2VENT is a latent heat thermal energy storage (LHTES) system that increases the capacity of the building to store heat. Using phase change materials, the system exploits the temperature difference between day and night time to maintain the thermal comfort within the recommended range. Acting as a cooling device, the unit stores energy during a cold night and releases it during the day to cool down the associated thermal zone. As a result, it can be seen as a complementary high-performance system for heating and cooling to reduce the peak loads. “We have introduced a novel process to form capsules of the phase change material in aluminium tubes. This type of encapsulation does not exist in the market, and if proved efficient, it could quickly find widespread use,” notes Dr Dugué. The encapsulation process allows better heat exchange between the air and the phase change material as it prevents changes in the material’s chemical composition, avoids interaction with the environment, and increases compatibility with the surrounding materials. Demo sites Two pilot buildings have been renovated with the E2VENT systems in Gdansk and Burgos to test the solutions in two different climates. The demonstration started in the University of Burgos with the renovation of the building composed of two classrooms. E2VENT solutions were also demonstrated on two flats in a demo site building in Gdansk. The elements composing the design in both sites were a certain number of SMHRV and LHTES units, and building energy management systems. An important part of the commissioning process were the acoustic tests conducted to find the maximum ventilator speed that generates noise which should be in line with existing acoustic standards. The proposed solutions for retrofitting old buildings should decrease primary energy needs by 50 % and significantly cut down CO2 emissions.
Keywords
E2VENT, buildings, façade, phase change material, energy efficiency, smart modular heat recovery ventilation (SMHRV), latent heat thermal energy storage (LHTES), indoor air quality, thermal comfort, energy management