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Title:
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Passiefhuis en EPN Onderzoek naar de waardering van passiefhuizen volgens EPN en PHPP
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Author(s):
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Boer, B.J. de; Kondratenko, I.; Jansen, D.; Joosten, L.; Boonstra, C.
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Published by:
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Publication date:
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ECN
Efficiency & Infrastructure
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28-7-2009
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ECN report number:
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Document type:
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ECN-E--09-054
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ECN publication
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Number of pages:
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Full text:
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52
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Download PDF
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Abstract:
Houses achieving the Passive House Standard are extremely well insulated and air-tight buildings with minimized heat losses, very efficient ventilation and optimized electricity use. The exceptionally low space heating energy demand is almost entirely covered by passive solar heat gains through windows and the use of incidental heat gains coming from people, household appliances and auxiliary systems. The remaining space heat demand is so little that a post-heating of ventilation air in heat recovery ventilation system suffices to obtain comfortable and healthy indoor climate.
It has been shown in many built examples throughout Europe and wider, the passivehouse concept can be reached in new build and in renovations, domestic and various other use of buildings. More so, there is growing justification and political commitment in European countries regarding the implementation of requirements towards very low energy buildings (on passive house level or similar). Therefore, passivehouse standard buildings can play an important role in reaching European and national targets for energy reduction from the built environment. In this context, it is very important that the calculation method in the Netherland that determines the energy performance of buildings (EPN) takes full account of passivehouse measures and their evaluation in the energy balance of a building is fully appreciated.
It is current impression amongst Dutch building energy specialists that implementing passivehouse measures when calculated with EPN are not favored correctly in the resulting EPC value. This study aims to make specific analysis and get insight into the way energy performance of passivehouses and its specific energy measures is calculated in EPN. Results were compared with the well established and internationally validated calculation tool Passive House Planning Package (PHPP).
The study methodology involved analyzing three SenterNovem reference houses (a terraced house, a detached house and an apartment building, all with EPC values of 0.8). In particular, the effect of introducing passive house measures (i.e. improved insulation, lower infiltration, and balanced ventilation) is examined, both in PHPP as in EPN.
The comparison study shows the total energy saving achieved with passivehouse measures are significantly lower in EPN calculations than PHPP calculations for all reference houses. For instance:
- Savings at EPC=0.8 terraced house (with self-regulating ventilation ducts) are 35% in EPN while this is 48% in PHPP.
- Savings at EPC=0.8 terraced house (with balanced ventilation system) are only 16% in EPN compared to 42% savings in PHPP. Also the calculations for the detached dwelling and the apartment building point out that the energy savings according to EPN are substantially lower than those according to PHPP.
The sensitivity analysis of passive house measures in EPN in comparison with the PHPP tool has identified the following main differences:
• the assumption value of internal heat gains (6.0 W/m2 in EPN versus 2.1 W/m2 standard at PHPP);
• the assumption value of indoor temperature (Ti = 18 °C at EPN or 20 °C in PHPP);
• appreciation of insulation value (i.e. improved u-value of building elements) is lower in EPN;
• appreciation of improved air tightness (limited value for infiltration in EPN);
• appreciation of improvement with efficiency of building systems for ventilation and hot water production and distribution systems (lower in EPN)
The relatively high heat gains in EPN give significantly lower heat demand both for the reference dwelling (EPC=0.8) and for the passivehouse variant. This is the reason why measures to reduce the heat demand in the EPN have little effect at all.
The study shows that the EPN calculation method is more rigid, less flexible and less dynamic compared to the PHPP calculation tool. It also has more fixed settings without possibility for user-value input. Therefore it has less possibility for detailed input and to be project specific. For example, in EPN there is no change in pump related energy (needed for operating the central heating system) when the space heating demand has decreased dramatically. Another example is the limit to the level of air tightness value, embedded in the EPN calculation, which shows no difference in results if one aims for better air-tightness.
Based on the study results, it can be concluded that the effect of passivehouse measures on the energy performance of dwellings is considerably less in EPN, when compared to the validated calculation programme PHPP.
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