Air tightness measurements in older Danish single-family houses
Lone H. Mortensen, Niels C. Bergsøe
2017
Energy Procedia
District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. The main scope of this paper is to assess the feasibility of using the heat demand
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... door temperature function for heat demand forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations. Abstract This paper reports and discusses the air tightness of the building envelope in existing single-family houses in Denmark. The air tightness of the building envelope depends in particular on the performance of specific construction details. There is a lack of knowledge about the air tightness of the building envelope of older buildings despite the fact that the air tightness has a major influence on the energy use. In connection with renovation of the Danish building stock, the coming years will see increased focus on the air tightness of the building envelope like in other countries. This paper presents the results of measurements in 16 single-family houses built between 1880 and 2007. The air tightness of the building envelope was measured according to EN ISO 9972 using the blower-door technique. The results are compared with measurement results of the average air-change rate in the same houses measured over a period of 1-3 weeks when the houses were in normal use. The measurement results of the air tightness of the building envelope range from 1.1 to 5.8 l/(s·m²) at 50 Pa. The investigated houses are all naturally ventilated. The results of the ventilation measurements showed an outdoor air supply ranging from 0.09 to 0.28 l/(s·m²) per heated floor area, which is below the requirement stipulated in the Danish Building Regulations of 0.3 l/(s·m²). Typically, leaks are observed in connection with penetrations of the envelope, e.g. for electrical installations, exhaust ducts and chimneys. In addition, leaks are observed around older windows and doors and in connection with wooden ceilings and attic hatches. The findings should be taken into account when renovating older single-family houses.
doi:10.1016/j.egypro.2017.10.016
fatcat:aplcg57g3bct3igqgoajfvre6q