Energy efficient production and distribution of domestic hot water in buildings with respect to the EC building directive and upcoming national guidelines for the energy-rating of buildings
The objective of the project is to propose more energy efficient and environmentally friendly solutions for DHW systems in buildings and promote the use of such systems.
It is likely that the production and distribution of domestic hot water in buildings will constitute a large part of the gross energy consumption in the upcoming energy-rating of buildings. Therefore it is the goal of this project to analyse existing conditions and to make guidelines for more energy efficient and substainable solutions. Measurements and analyses will be carried out in 10-12 buildings (block of flats, semi-detached houses, institutions) of present standard. After the analysis of existing conditions has been completed, proposals for a more energy-efficient production and distribution of domestic hot water will be worked out. Methods for reducing the heat loss from domestic hot water production and distribution will be analysed, including new types of pipes (twin pipes, concentric pipes), which are expected to be able to reduce the heat loss by up to 40%. Energy-rating and environmental conditions for different solutions will be compared. In case of district heated buildings, it is very important to obtain a low return temperature from the domestic hot water system, besides to reduce the internal losses inside the building. Results and proposals for energy-efficient solutions will be recommended to legislators, housing companies and other building owners. The results will be of great importance not only for future buildings but also for existing buildings when they are being renovated
Based on the results of the project the fol-lowing recommendations are pointed out. - In large buildings e.g. apartment buildings and office buildings the technical installations should be pro-vided with meters so that it is possible to separate the energy consumption for DHW, space heating and ventilation, respectively. Thorough knowledge of the individual consumptions is a prerequisite for estima-tions on potential energy savings. Only in a few of the investigated buildings was a heat meter for DHW al-ready fitted. - In new buildings and in case of retrofitting existing buildings, careful planning of the placement and dispo-sition of hot water taps compared with the location of the hot water tank or heat exchanger is recom-mended. Also, the necessity of a circulation line or use of HWAT should be carefully analysed. - For office buildings it is recommended to consider the use of a decentralized, electrical hot water produc-tion in preference to a traditional solution with circulation lines. Even if the electricity consumption is weighted by a factor of 2.5 it may be advantageous to use - For apartment buildings, the trend is that it should be possible to measure the consumption in each individ-ual apartment. Therefore, flat stations with a district heating unit in each apartment should be compared with traditional ways of supplying and measuring heat to apartments (heat allocators). - New types of circulation lines should be considered, e.g. concentric pipes or twin pipes, which may reduce pipe heat losses considerably. Also, prefabricated vertical pipes should be considered. Regulations as re-gards inaccessible joints and penetrations including requirements regarding precautionary measures con-cerning fire must be observed. - It is recommended that in depth analyses are conducted on how much of the heat loss from the DHW sys-tem that actually can be utilised in a building
Key figures
Category
Participants
| Partner | Subsidy | Auto financing |
|---|---|---|
| Aalborg Universitet (Fredrik Bajers Vej) | ||
| ALECTIA A/S |
Contact
Niels Koppels Alle, Bygning 402
DK-2800 Kgs. Lyngby, Denmark
www.mek.dtu.dk
Bøhm, Benny (Dr. Techn.) , 45254024, bb@mek.dtu.dk
Øvr. Partnere: Birch og Krogboe A/S; Statens Byggeforsknings Inst.
