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Experimental evaluation of airflow in a low-energy building
Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
2006 (English)In: The International Journal of Ventilation, ISSN 1473-3315, Vol. 5, no 2, 239-248 p.Article in journal (Other academic) Published
Abstract [en]

This paper reports on tracer gas measurements of the ventilation flow within a low-energy building. Constant-concentration, decay and homogenous tracer gas emission methods were used. Low-energy buildings are airtight constructions; effective ventilation is thus very essential for the indoor climate. The results of this study show an airflow rate between 0.42 and 0.68 air exchanges per hour (ac/h), which should be compared to the minimum requirements in Sweden of 0.5 ac/h. It was found that the airflow changes with time and that the local mean age of air was different on different floors of the building and, to some extent, different at different heights.

Place, publisher, year, edition, pages
2006. Vol. 5, no 2, 239-248 p.
Keyword [en]
ventilation, low-energy building, tracer gas, constant concentration, decay, homogenous concentration emission, dwellings
National Category
Engineering and Technology
URN: urn:nbn:se:liu:diva-14152OAI: diva2:22750
Available from: 2006-11-30 Created: 2006-11-30 Last updated: 2009-03-10
In thesis
1. Multi-dimensional approach used for energy and indoor climate evaluation applied to a low-energy building
Open this publication in new window or tab >>Multi-dimensional approach used for energy and indoor climate evaluation applied to a low-energy building
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The building sector alone accounts for almost 40% of the total energy demand and people spend more than 80% of their time indoors. Reducing energy demand in buildings is essential to the achievement of a sustainable built environment. At the same time, it is important to not deteriorate people’s health, well-being and comfort in buildings. Thus, designing healthy and energy-efficient buildings is one of the most challenging tasks. Evaluation of buildings with a broad perspective can give further opportunities for energy savings and improvement of the indoor climate.

The aim of this thesis is to understand the functionality, regarding indoor climate and energy performance, of a low-energy building. To achieve this, a multi-dimensional approach is used, which means that the building is investigated from several points of views and with different methods. A systems approach is applied where the definition of the system, its components and the border to its environment, is essential to the understanding of a phenomenon. Measurement of physical variables, simulations, and qualitative interviews are used to characterize the performance of the building. Both energy simulation and computational fluid dynamic simulations are used to analyse the energy performance at the building level as well as the indoor climate at room level. To reveal the environmental impact of the low-energy building studied in this thesis the CO2 emissions and embodied energy have been investigated regarding different surrounding energy systems. The evaluated building is situated at the west coast of Sweden and uses about 50% of energy compared to a comparable ordinary Swedish building. The building is well-insulated and an air-to-air heat exchanger is used to minimise the heat losses through ventilation. The houses are heated mainly by the emissions from the household appliances, occupants, and by solar irradiation. During cold days an integrated electrical heater of 900 W can be used to heat the air that is distributed through the ventilation system. According to measurements and simulations, the ventilation efficiency and thermal environment could be further improved but the occupants are mostly satisfied with the indoor climate. The control of the heating system and the possibility for efficient ventilation during summertime are other important issues. This was found through quantitative measurements, simulations and qualitative interviews. The low-energy building gives rise to lower CO2 emissions than comparable buildings, but another energy carrier, such as district heating or biofuel, could be used to further improve the environmental performance of the building. The total energy demand, including the embodied energy, is lower than for a comparable building.

To understand the functionality of a low-energy building both the technical systems and the occupants, who are essential for low-energy buildings, partly as heat sources but mainly as users of the technical systems, should be included in the analysis.

Place, publisher, year, edition, pages
Institutionen för konstruktions- och produktionsteknik, 2006
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1065
Low-energy building; energy; indoor climate; simulation, Lågenergihus; energi; inomhusklimat; simulering
National Category
Building Technologies
urn:nbn:se:liu:diva-7819 (URN)91-85643-21-1 (ISBN)
Public defence
2006-12-15, C3, Hus C, Linköpings universitet, Linköping, 10:15 (English)
Available from: 2006-11-30 Created: 2006-11-30 Last updated: 2009-03-02

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Karlsson, Fredrik
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