Jensen, Rasmus Lund

Larsen, Tine Steen

English

The paper describes the first results from a large Danish project regarding measurements of energy performance and indoor environmental quality in 10 Danish Passive Houses. The project includes both qualitative and quantitative analyses. This paper describes the first results from the quantitative part.The house considered in this paper has an air change rate (ACR) of 0.34 h-1 and the results from the first few months of measurements show excellent results when relative humidity (RH) and CO2-levels are considered. When the temperatures are assessed problems with slight overheating are found. One of the main reasons for this is the low solar angles during spring combined with the lack of solar shading and a low ACR. Solar shading and increased ventilation should be able so solve the problem. The energy consumption for room heating show a very low consumption as expected whereas the energy used for heating domestic hot water is very similar to conventional houses.The paper describes the first results from a large Danish project regarding measurements of energy performance and indoor environmental quality in 10 Danish Passive Houses. The project includes both qualitative and quantitative analyses. This paper describes the first results from the quantitative part.The house considered in this paper has an air change rate (ACR) of 0.34 h-1 and the results from the first few months of measurements show excellent results when relative humidity (RH) and CO2-levels are considered. When the temperatures are assessed problems with slight overheating are found. One of the main reasons for this is the low solar angles during spring combined with the lack of solar shading and a low ACR. Solar shading and increased ventilation should be able so solve the problem. The energy consumption for room heating show a very low consumption as expected whereas the energy used for heating domestic hot water is very similar to conventional houses

    Aalborg UniversitetMeasurements of Energy Performance and Indoor Environmental Quality in 10 DanishPassive Housesa case studyLarsen, Tine Steen; Jensen, Rasmus LundPublished in:Healthy Buildings 2009Publication date:2009Document VersionPublisher's PDF, also known as Version of recordLink to publication from Aalborg UniversityCitation for published version (APA):Larsen, T. S., & Jensen, R. L. (2009). Measurements of Energy Performance and Indoor Environmental Qualityin 10 Danish Passive Houses: a case study. In Healthy Buildings 2009: 9th International Conference &Exhibition, September 13-17, 2009, Syracuse, NY USAGeneral rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright ownersand it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.            ? Users may download and print one copy of any publication from the public portal for the purpose of private study or research.            ? You may not further distribute the material or use it for any profit-making activity or commercial gain            ? You may freely distribute the URL identifying the publication in the public portal ?Take down policyIf you believe that this document breaches copyright please contact us at vbn@aub.aau.dk providing details, and we will remove access tothe work immediately and investigate your claim.Proceedings of Healthy Buildings 2009                   Paper 319  Measurements of energy performance and indoor environmental quality in 10 Danish Passive Houses – a case study  Tine Steen Larsen1,*, Rasmus Lund Jensen1  1Aalborg University, Denmark  *Corresponding email: tsl@civil.aau.dk   SUMMARY The paper describes the first results from a large Danish project regarding measurements of energy performance and indoor environmental quality in 10 Danish Passive Houses. The project includes both qualitative and quantitative analyses. This paper describes the first results from the quantitative part.   The house considered in this paper has an air change rate (ACR) of 0.34 h-1 and the results from the first few months of measurements show excellent results when relative humidity (RH) and CO2-levels are considered. When the temperatures are assessed problems with slight overheating are found. One of the main reasons for this is the low solar angles during spring combined with the lack of solar shading and a low ACR. Solar shading and increased ventilation should be able so solve the problem. The energy consumption for room heating show a very low consumption as expected whereas the energy used for heating domestic hot water is very similar to conventional houses.  KEYWORDS  Measurements, energy consumption, indoor environmental quality, passive houses  INTRODUCTION During 2008 ten passive houses were built near Vejle in Denmark as a result of the development project “The Comfort Houses”. The houses are some of the first passive houses in Denmark and all of them will be certified after the German passive house standard (Feist et al. 2005). The 10 houses all have different architectural expressions. Some houses are built as traditional Danish brick houses, some are made from precast concrete units, some with wood casing, some with plaster – all different houses where also different building technological solutions were used (www.komforthusene.dk, 2009). The idea of choosing different constructions of the houses also makes the project unique since it will be possible to demonstrate that passive houses in a Northern European context also can fit into the local architecture and building tradition.   Even though the houses are quite different one thing has to be common for all of them. They all have to comply with the passive house standard, which means having a heat demand lower than 15 kWh/m2 pr year, a total primary energy consumption lower than 120 kWh/m2 pr year and finally having an infiltration lower than 0.6 h-1 with a pressure difference of 50 Pa. (Feist et al. 2005). Since a very simple way to lower the energy consumption is to lower the air change rate of course this possibility has been discussed during the design phase. Today the Danish building regulations require an air change rate of 0.5 h-1 with a standard room height of 2.5 m but the Comfort Houses has obtained an exemption from the regulations and are allowed to lower this down to 0.3h-1.   Proceedings of Healthy Buildings 2009                   Paper 319  Lowering the air change rate of course will result in lower heat demands for the houses but it will also increase the risk of poor indoor environmental quality (IEQ). In order to follow this, and also document whether the calculated energy consumption will correspond to the measured value, a program for measurements was set up for the houses. Earlier work within documentation of IEQ and energy consumption in passive houses mainly focuses on the thermal part of the indoor environment (Feist et al. 2001, Schnieders et al. 2006 and Wall 2006) but in this project the atmospherically part will also be included by measurements of relative humidity and CO2. This is done to ensure that a good and healthy indoor environment has been achieved and has not been overruled by achieving low energy consumption.  METHODS  In order to document the function of the 10 houses both qualitative and quantitative analyses have been applied. The aim of the qualitative analyses is to obtain knowledge about the residents, their behaviour in the house and their reasons for buying a passive house. These analyses consist of two separate visits in each of the houses where questionnaires are sent beforehand and followed up by interviews on the day of the visit. The first visit is made just after the taking up residence of the new passive house, with the aim of obtaining knowledge of their earlier (reference) house. The second visit is made after one year of habitation in the house and will focus on their routines and experiences with their life in a mechanically ventilated passive house. The results of the qualitative measurements are not included here.  The quantitative analyses consist of detailed continuous measurements of the indoor environment and the energy consumption in the houses. For assessment of IEQ wireless sensors are used for measurements of room air temperature, relative humidity and CO2 in living room, kitchen, one or two bedrooms and a bathroom in each house. The measurements regarding energy consumption are carried out in the scullery through both electricity meters and energy meters. The electricity consumption is split into several meters in order to obtain detailed knowledge about the amount of electricity used for ventilation, household, heat pumps etc. The energy meters are split into one part measuring energy consumption for hot water production and another measuring energy send into the house through floor heating, ventilation air or, in some houses, just regular heaters coupled to a heat pump.  The last part of the data collection is measurements made in the ventilation systems, which in most of the houses are included into a compact unit, which also produces hot water. Here humidity and temperature are measured in order to calculate the efficiency of the heat exchanger in the different systems, and also to be able to calculate the COP of the unit and the heat pumps build into some of the systems. Besides the continuous measurements, also measurements of daylight conditions and acoustics are made during single visits to the houses.   Since one of the main aims of the project is to register what happens in the houses and also avoid influencing the daily routines and habits of the residents, it was important to choose equipment that would be “invisible”. Data from the houses are collected and send through the internet to an energy management system (EMS). Here all measurements can be followed from a remote position which also means, that we do not have to visit the houses frequently to empty dataloggers and check equipment. Data is collected every 5th minute throughout the year. The measurements started during March 2009 and will continue for 30 months.   RESULTS The results presented here will be based on the very first indications. Further details and analysis will follow during the next three years of continuous measurements. Proceedings of Healthy Buildings 2009                   Paper 319  Case study: Single-family house, 145 m2 net area, 362 m3 (net volume), 2 adults, 1 child The house (see Figure 1) is made of brick walls (both inner and outer walls) with 380 mm insulation in between. The main living area is facing nearly south whereas kitchen and bathrooms have northern positions. A floor plan can be seen in Figure 2. The house is mechanically ventilated with air inlet into “clean” zones (red zones in Figure 2) and air exhaust from the more polluted zones as kitchen, bathrooms and scullery (blue zones in Figure 2). The average air change rate is 0.34 h-1, but the system is demand controlled and the user can manually increase the volume flow by 25% by pushing the “party” button in the living room. This option was used a single time during the first 1½ month of measurements.  Indoor environmental quality From the very first analyses it is found that high temperatures in the living areas are the main problem. In average the CO2 level in the house is around 650 ppm and it only gets above 800 ppm a few times (see Figure 3), which must be considered as good in a single family home (corresponds to category I in the European standard EN 15251 (CEN 2007)). This is found for both March and April. Also the relative humidity is found to be acceptable with a maximum of 54%. The minimum value of 22% is a little critical but is only reached for a short period due to the cold outdoor temperatures during night in the same period (see Figure 3 / Figure 4). 20304050607080Relative humidity [%]020040060080010001200CO2 concentration [ppm]Relative humidity CO2 concentration1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30   0510152025301 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30Temperature [°C]Indoor Temperature Average indoorOutdoor Temperature  When the indoor temperature is considered, the increasing level of the outdoor temperature and the higher solar gains is reflected directly at the indoor temperature measured during April, which several times are above the level for thermal comfort during this season. The temperature is higher than 26°C for 105 hours which will classify the house as category III according to CEN 2007.  Here a typical problem for passive houses is seen. Since the house is very well insulated it will overheat very fast, and will probably have a great need of solar shading, which in this case is absent. The only shade provided is at midsummer from the overhang above the southern windows of the house (seen in Figure 1). Another solution will be to increase the Figure 2. Floor plan Figure 1. The studied passive house. Façades towards south and east. Figure 3. Measured relative humidity and  Figure 4. Measured indoor and outdoor CO2 concentration during April 2009.  temperature during April 2009.  Proceedings of Healthy Buildings 2009                   Paper 319  natural ventilation by opening windows but this solution is limited to the periods where the house is occupied due to the risk of theft.   Energy consumption The heat demand of the house is covered by an efficient heat recovery cross flow unit in the ventilation system, with a recovery ratio of 75.3% and a possibility to bypass the inlet air manually.  Besides the heat recovery unit a supplementary water based heating surface for additional heating of ventilation supply air is used and finally a water based floor heating system in the two bath room floors and a small area in the living room is installed. The water based heating is produced by a ground source heat pump with a COP varying between 3.05 (summer) and 3.58 (winter). During the first 1½ months of measurements the floor heating system has only been activated three times with a total heat consumption of 23 kWh. In the same period the heat consumption for domestic hot water was 220 kWh.   DISCUSSION A simple way of saving energy is by lowering the ACR and of course this option can be considered when houses are being designed, but it must never become a solution which overrules the demands for a good and healthy indoor environment. Therefore it is important to find the balance between saving energy and obtaining good IEQ. In the search for this balance it is important to consider not only the thermal part of the indoor environment but also the RH and CO2-levels, which in some parts of the year also will be important factors (Jensen, 2008)  CONCLUSIONS The first indications of the IEQ in one of the first Danish passive houses show excellent results when both RH and CO2 are considered. The temperature levels show problems with overheating which mainly are caused by the low solar angles during spring. Solar shading and increased ventilation should be able so solve this problem. The results from measurements of energy consumption for room heating show a very low consumption as expected whereas the energy used for heating domestic hot water is very similar to conventional houses.    ACKNOWLEDGEMENT The project is supported by Realdania, Saint-Gobain Isover A/S, Tre-For and Nilan A/S.  REFERENCES  CEN 2007. European Committee for Standardization En15251. Indoor environmental input parameters for design and assessment of energy of buildings addressing indoor air quality, thermal environment, lighting and acoustics. Feist W., Peper S. and  Görg M. 2001. CEPHEUS-Project information No. 36 Final Technical Report. Project Reference Number: BU/127/DE/SE/AT, 127 pages. Feist W., Schnieders J., Dorer V. and Haas A. 2005. Re-inventing air heating: Convenient and comfortable within the frame of the Passive House concept. Energy and Buildings 37, pp.  1186–1203 Jensen, R.L. and Brunsgaard, C. 2008. Necessary Air Change Rate in a Danish Passive House. In proceedings of The 12th International Conference on Passive Houses, Nuremberg, Germany. 14 pages.  Schnieders J. and Hermelink A. 2006. CEPHEUS results: measurements and occupants’ satisfaction provide evidence for Passive Houses being an option for sustainable building. Energy Policy 34, pp. 151–171 Wall M.  2006. Energy-efficient terrace houses in Sweden - Simulations and measurements. Energy and Buildings 38, pp. 627–634 www.komforthusene.dk, April 2009 

Measurements of Energy Performance and Indoor Environmental Quality in 10 Danish Passive Houses:a case study

https://vbn.aau.dk/ws/files/18898018/Measurements_of_Energy_Performance_and_Indoor_Environmental_Quality_in_10_Danish_Passive_Houses

Measurements of Energy Performance and Indoor Environmental Quality in 10 Danish Passive Houses:a case study

Abstract

Similar works

Full text

Available Versions

VBN