THE APPLICATION OF ADVANCED DEHUMIDIFICATION TECHNIQUES TO COMBAT CONDENSATION IN HOUSEHOLDS

Cel

Alleviation/cure of condensation dampness and mould growth in households by extracting moisture from the air, thereby reducing the requirement for high ventilation rates and wasteful space heating. The dehumidifier is estimated as achieving on average a 1/2 kW heat input energy saving. Electricity saving is expected to reach 1,550 kWh/yr per dwelling. Investment cost should be 250 UKL per unit, plus 50 UKL per installation. Expected payback time is 2.3 years.
Analysis of the winter 86-87 monitoring shows that:
- the efficiency is not as high as expected because the deshumidifiers are not running continuously. Several start up/stop are observed.
- the occupants are generally satisfied and a significant improvement about moisture effects is observed.
This analysis is confirmed during the winter 87-88.
The mean values measured in 10 houses fitted with kWh-meters are as follows for one week : 3,0 to 21,0 kWh for water extraction of 1,9 to 14,2 liters resp., giving an efficiency of extraction between 0,73 and 1,74 kWh/liter of water.
- The annual energy saving for one house, with the dehumidifier in partial activity (60 %) during 6 winter months, is calculated as follows :
a) heat restored (500 W) for space heating, from the latent heat of treated air = 1310 kWh
b) electricity needed (380 kWh)
c) further saving (300 W) by reduced ventilation when dehumidifier is not running (40 % of time) : 524 kWh

giving an overall figure of 1310 - 380 +524 = 1454 kWh.
- The inside relative humidity is controlled and is generally below 70 %.
- The qualitative aspect of the project was treated by questionnaires sent after each winter; the analysis of the answers shows that the tenants who returned questionnaires that indicated they were suffering from mould growth and had cleaned it off after the dehumidfier was installed, has a 77-78 % chance of the mould growth not returning.
The general comments indicated that the tenants were happy with the dehumidifier.
1. Dehumidifiers operate using the same thermodynamic principles and components as a domestic refrigerator, having a compressor, and expansion valve, a cold evaporator coil and a hot condensor coil.
A small fan draws air laden with moisture through the evaporator which cools it below dew point temperature. This causes condensation of water on the evaporator coil surfaces. The water then drains away under gravity into a collector bucket, or is piped away to the exterior of the dwelling. The cooled, dryed air then passes over the hot condenser coil and returns to the room, warmer and dryer. All of the electrical energy consumed by the dehumidifier's fan and compressor is returned to the atmosphere as heat. In addition, the latent heat of vaporisation of the condensing moisture, is transferred to the out-going air. The dehumidifier therefore, supplied 10 to 30% more heat energy to the surrounding room than it consumes electrically and for this reason the machine is often referred toas a 'heat pump dehumidifier'.
2. Substantial improvements in the performance of conventional dehumidifiers can be made by installing a specially designed heat exchanger between the evaporator and condenser. The cold air from the evaporator is used to cool the incoming air and it in turn is heated before passing over the condenser. In short, this improves the thermodynamic efficiency of the system which is reflected in the efficiency as a significant reduction in the electricity required to extract a given amount of water from the air. A dehumidifier which incorporates these operating features is known as an 'advanced' (or geared) dehumidifier.
3. The power of a single unit is 145 W. The project is to be carried out in approximately 100 Council-owned dwellings in various properties (houses, flats, maisonettes, bungalows), ages, construction and exposure to climatic conditions.

Program(-y)

ENG-ENALT 2C - Programme (EEC) of demonstration projects relating to the exploitation of alternative energy sources and to energy saving and the substitution of hydrocarbons, 1983-1985

Temat(-y)

3.1 - BUILDINGS

Zaproszenie do składania wniosków

Data not available

System finansowania

DEM - Demonstration contracts

Koordynator

SHEFFIELD CITY COUNCIL

Wkład UE

Brak danych

Adres

TOWN HALL
S1 1UJ SHEFFIELD
Zjednoczone Królestwo

Koszt całkowity