Energy-efficient houses built according to the energy performance requirements introduced in Denmark in 2006

doi:10.1016/j.enbuild.2006.12.011

Energy and Buildings

Volume 39, Issue 10, October 2007, Pages 1123-1130

https://doi.org/10.1016/j.enbuild.2006.12.011 Get rights and content

Abstract

In order to meet new tighter building energy requirements introduced in Denmark in 2006 and prepare the way for future buildings with even lower energy consumption, single-family houses were built with the purpose to demonstrate that it is possible to build typical single-family houses with an energy consumption that meets the demands without problems concerning building technology or economy. The paper gives a brief presentation of the houses and the applied energy-saving measures. The paper also presents results from measurements of the overall energy use, indoor climate and air tightness. Furthermore, results from detailed calculations of the utilization of electricity-related heat gains are presented. Looking at the energy consumption in relation to the new energy requirements, the paper concludes that the single houses can relatively easily keep the future energy demands. The energy consumption of the houses is on a level corresponding to a classification as “low-energy house class 2” or an energy consumption of 75% of the required maximum energy consumption. With minor modifications, some houses could be classified as “low-energy building class 1” corresponding to an energy consumption of only 50% of the required and almost the level of typical passive houses.

Introduction

The European building sector is responsible for about 40% of the total primary energy consumption. To reduce this share, the European Commission has put forward a directive on Energy Performance of Buildings, the EPBD (2002/91/EC), which came into force 2002 and should be implemented in the legislation of member states in 2006. Unfortunately many member states have not yet managed to comply. The status of the EPBD implementation can be followed on the web, i.e. http://www.epbd-ca.org/ or http://www.buildingplatform.org/. In addition to the aim of improving the overall energy efficiency of new buildings, large existing buildings will become a target for improvement, as soon as they undergo significant renovation.

An important aim of the directive is to improve the overall energy efficiency of new buildings. Therefore the directive lay down requirements to a methodology of calculation of the integrated energy performance and the application of minimum requirements on the energy performance of buildings.

New energy performance requirements in accordance with the directive were introduced in Denmark in 2006, which will reduce the energy consumption in new buildings by 25–30% compared to current demands.

According to the new requirements, new houses should meet an energy frame, i.e. maximum total energy consumption, including energy for heating, ventilation, cooling and hot water. At the same time a classification system is introduced, where buildings can be classified as being a “low-energy building class 1” or a “low-energy building class 2”. The new classification system will make it possible for building contractors to better promote low-energy houses for the consumers, and the public will be able to demand that their new houses have a better energy performance than the minimum requirements specified in the Building Regulations.

In order to meet these new energy requirements and prepare the way for future buildings with even lower energy consumption, a number of detached single-family houses with new types of building envelope structures and ventilation with heat recovery, etc. were built with the purpose to demonstrate that it is possible to build typical single-family houses with an energy consumption that meets the demands without problems concerning building technology or economy.

Introducing the new energy regulations, the energy requirements on buildings will be based on the overall energy use of the building, converted to primary energy by use of specific Danish primary resource energy factors, corresponding to the energy delivered to the building except electricity consumption for household appliances.

This paper describes measurements during the heating season of 2003/2004 of the overall energy use on several of the described single-family houses that represent ordinary building systems in Denmark. The objective has been to document and analyze the measurement results that have come to light and to compare with future requirements on the total energy consumption.

The measurements include measurements of the electrical consumption for heating and ventilation (pumps and fans) and also household appliances. Since, a reduction of the heat loss by better insulation and ventilation with heat recovery results in a shorter heating season and – all other things being equal – less utilization of the “free” heat from electricity consumption, the influence of the electricity consumption on the heat consumption has been investigated by means of calculations based on the measurements.

A similarly project was carried out in Sweden [1] involving terrace houses built in 2001. However, these houses had better overall energy-efficiency, i.e. passive house standard, and solar collectors were used for domestic hot water. Passive House is the world leading low-energy building concept and was developed in Germany [2]. The first house was built in 1991 and the concept is nowadays primarily used in German-speaking countries and Scandinavia. Other low-energy demonstration projects are described in [3], [4], [5]. In Denmark, there is a growing awareness of the concept as a solution to achieve high thermal comfort conditions and a low energy demand on low construction costs. Some innovative Danish building envelope components for passive houses are described in [6].

Section snippets

Description of experimental houses

Energy efficient single-family houses that meet the new energy performance requirements in Denmark have been developed and built during the last couple of years. Pictures of the houses that were built and an outline of location, type of building system etc., are shown in Fig. 1 and Table 1. All houses (except for house C in Table 1) have floor heating systems, are supplied with district heating and have mechanical ventilation with heat recovery.

Table 2 below presents geometrical data. The net

Building technology, indoor climate and financial aspects

Development of a low-energy house with a good indoor climate calls for a suitable application of various measures in different fields:

•
Building geometry and orientation,
•
Insulation of building envelope constructions,
•
Air tightness of building envelope constructions,
•
Utilisation of passive solar energy; elaboration, placement and orientation of windows,
•
Regulation of passive solar energy; solar shading systems (passive or active),
•
Ventilation system; high-efficiency heat recovery, fans and controlling

Measurement results

Measurements of energy consumption for space heating, domestic hot water (DHW) and electricity consumption were carried out in the project [12]. In addition, solar radiation, outdoor and indoor temperatures and temperatures in heating and ventilation systems were measured. Results are presented for houses A, B and E. Houses C and D were not occupied. Houses A and B were occupied by families with small children, whereas two adults were living in house E.

Measurement versus calculations—heating demand

Calculations have been made on the heating demand based on the measured air leakage, room temperature and weather data for the same periods as in Table 4. The calculations have been carried out in the Danish building simulation program BSIM [7] with the objective of validating the model. Measured and calculated heating demands are shown in Fig. 4.

It appears that there is a good agreement between the detailed calculations and the achieved test results. The calculation model somewhat

Measurements versus anticipated requirements—overall energy use

In the light of the performed measurements and new energy demands in 2006, comparisons are made regarding the measured energy consumption and the energy frame. As previously mentioned the energy frame is the maximum allowed delivered energy excluding electricity for household appliances.

The energy frame is calculated as 70 + 2200/A_gross (kWh/m² a). Electricity consumptions should be transformed into primary energy using a factor 2.5 according to the Danish Energy Agency. The measured energy

Electricity consumption—influence on consumption of energy for heating

The electricity consumption is transformed into heat that can potentially be utilized for space heating. If the electricity consumption is reduced by using low-energy products, this will, other things being equal, increase the energy consumption for space heating. The utilization of the electricity-related heat (and also heat from people) is impeded by the fact that it falls at times when there is no demand for heat. In addition, a reduction of the heat loss by better insulation and ventilation

Conclusion

Measurements have been made of the overall energy use of three Danish single-family houses built according to energy performance requirements introduced in Denmark in 2006.

The energy consumption for space heating, determined by detailed calculations based on the measured air leakage, room temperature and weather, roughly corresponds to the obtained test results (the divergence is only a few per cent). However, the energy consumption is larger than expected. This is mainly due to the fact that

Acknowledgements

The work on which this paper is based was funded by the Associated Danish Distributors of Electricity (ELFOR) and The Danish Energy Authority (ENS).

References (12)

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Energy-efficient houses built according to the energy performance requirements introduced in Denmark in 2006

Abstract

Introduction

Section snippets

Description of experimental houses

Building technology, indoor climate and financial aspects

Measurement results

Measurement versus calculations—heating demand

Measurements versus anticipated requirements—overall energy use

Electricity consumption—influence on consumption of energy for heating

Conclusion

Acknowledgements

Energy and Buildings

Energy and Buildings

Energy and Buildings

Innovative Danish building envelope components for passive houses