| 1. |
- Johansson, Dennis, et al.
(författare)
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Measurements of occupancy levels in multi-family dwellings-Application to demand controlled ventilation
- 2011
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Ingår i: Energy and Buildings. - : Elsevier BV. - 0378-7788 .- 1872-6178. ; 43:9, s. 2449-2455
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Tidskriftsartikel (refereegranskat)abstract
- The occupancy level of dwellings is an important parameter to know to determine the energy efficiency, energy use and indoor air quality, especially in low-energy buildings where the user-related energy uses, such as household electricity and domestic hot water heating, are significant parts of the energy balance in a building. For residential buildings, there is a lack of occupancy level data, which also needs to be resolved over time, in a way so that both short term and long term variations can be described. As a part of an ongoing study, occupancy levels were measured as building average levels in 18 apartment buildings containing 342 apartments in total with readings every 30 min for more than a year. Averages and standard deviations of occupancy level, and variation in occupancy during the year, week and day respectively are presented. The results show a highly varying occupancy level over time, which indicates the potential of demand controlled ventilation in dwellings. (C) 2011 Elsevier B.V. All rights reserved.
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| 2. |
- Simanic, Branko, et al.
(författare)
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Influence of user-related parameters on calculated energy use in low-energy school buildings
- 2020
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Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 13:11
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Tidskriftsartikel (refereegranskat)abstract
- Literature and experience show that there are large discrepancies between the calculated and measured building energy usages, where user-related parameters are significant factors with regard to energy use in low-energy buildings. Furthermore, the difficulties encountered when quantifying these parameters compound these discrepancies. The main aim of this study was to provide feedback that would help the building industry and research communities to predict more accurately the impact of the user-related parameters on energy performance. The results of the study would, subsequently, contribute to minimizing the discrepancies between calculated and measured energy use. This article analyses simulated building energy use based on randomly chosen combinations of measured user-related parameters in three recently built low-energy schools in Sweden. The results show that energy performance can span from 30 to 160 kWh/(m2 y) simply by varying the combination of previously measured user-related parameters in building energy simulations. The study shows that the set points for indoor air temperatures during the heating season and the energy required to run a demand-controlled ventilation system have an extensive influence, while tenant electricity use has a slightly lower influence on building energy use. Variations in occupancy rates and energy for hot water usage have the smallest influences on building energy use.
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| 3. |
- Abdul Hamid, Akram, et al.
(författare)
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Impact of high residential density on the building technology, HVAC systems, and indoor environment in Swedish apartments
- 2020
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Ingår i: E3S Web of Conferences. Volyme 172, 2020.. - : EDP Sciences. ; 172
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Konferensbidrag (refereegranskat)abstract
- During the last few years, there has been an increased number of overcrowded apartments, due to increased migration but also housing shortage in general, particularly in the suburbs to major cities. The question is how the indoor environment in these apartments is affected by the high number of persons and how the problems related to high residential density can be overcome. This paper aims to specify the problem by investigating and analysing the technical parameters influenced by residential density in Swedish apartments built between 1965-1974. To map the situation, 11 interviews with employees at housing companies were conducted. Based on extreme conditions described in the interviews, simulations of the indoor climate and moisture risks at some vulnerable parts of constructions were made. Simulations were focused on moisture loads and CO2 concentrations as functions of residential density and ventilation rate. Finally, measures to combat problems associated to overcrowding are suggested. The aim is that the results should be used by authorities to formulate incentives and/or recommendations for housing companies to take actions to ensure a good indoor environment for all, irrespective of residential density conditions. © The Authors.
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| 4. |
- Abdul Hamid, Akram, et al.
(författare)
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Measuring the impact of MVHR on the energy efficiency and the IEQ in multifamily buildings
- 2019
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Ingår i: Energy and Buildings. - : Elsevier BV. - 0378-7788. ; 195, s. 93-104
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Tidskriftsartikel (refereegranskat)abstract
- Renovating and improving the current building stock is a matter of both need and importance. In order to know if the implemented renovation measure has had an impact on the building as a system it is important to verify the impact through measurements. The aim of this project is to isolate the impact of a measure on the energy efficiency of a building as well as the indoor environmental quality. This, through detailed measurements that enable the exclusion of the impact of other factors that might affect the energy use. For this reason a mechanical ventilation system with heat recovery was installed in two apartment buildings and measurements were conducted before and after installation. Measurements were also conducted in two almost identical reference buildings, that were used as a control group for the experiment. Together with acquired data for the surrounding climate, measurements were conducted on 1)the district heat carriers to and from the buildings, 2)the temperature and relative humidity in the apartments, 3)the global horizontal radiation on site, and 4)the temperature outdoors. A survey was also conducted with the inhabitants for the assessment of the impact on the perceived indoor environmental quality. Correcting for the outdoor temperature only, a yearly reduction by 22% and 24% is achieved in the affected buildings. Changes in the global horizontal radiation clearly impact the results, however, can not be corrected for. By using the control group as a reference, further corrections can be made and the energy reduction might be determined to 15% and 34%, instead of 22% and 24% respectively.
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| 5. |
- Fransson, Victor, et al.
(författare)
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A method to estimate absence in apartments based on domestic water use
- 2020
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Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323. ; 180
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Tidskriftsartikel (refereegranskat)abstract
- Today, every new building is constructed with the ambition of it having a very low energy demand or even being completely neutral with regard to supply and demand over a year. In modern low energy or nearly zero energy residential buildings like these, the behaviour of the occupants becomes increasingly more significant in terms of the energy performance of the building. Occupants who are present and using appliances reduce the amount of heat needed to be supplied by the heating system. Knowledge about occupant behaviour is, consequently, of great importance. As occupants’ presence, absence and behaviour are hard to measure without being intrusive, the level of occupancy is often derived from statistics gathered from questionnaire surveys or from measurements of other variables connected to occupancy, such as household electricity use. This study investigates such measurement data with regard to the use of household electricity, domestic hot water and domestic cold water gathered at hourly intervals over a whole year in over 1,000 Swedish apartments. A method is proposed whereby an apartment is regarded as being empty if no water (hot or cold) is used during an entire day. Using this method, 50% of the apartments were found to have 10 days of absence or more, and for apartments in the interquartile range, i.e. the 50% closest to the median, the periods of absence varied between 1 and 31 days. The validation showed an increase of absence during national holidays by about 300%, and by about 100% during weekends. The outcome of estimating absence using only one of the variables was evaluated and it was shown that domestic cold water use would be a good substitute method with 98% precision.
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