Passive building: progressive insight into energy-saving building
The future lies in passive building. Passive building means maximum comfort with minimal energy consumption. Passive building is a method of building that can reduce energy consumption even further than it is today. A passive house can be heated using a maximum of 15 kWh per square meter of floor area per year. This corresponds to an energy performance coefficient (EPC) of approximately 0.3-0.4 compared with the current Dutch EPC of 0.8. This represents a saving of at least fifty percent.
Passive building is not new. Various projects have already been carried out in neighbouring countries. In the last ten years, the building of more than ten thousand 'Passivhäuser' in Germany and Austria has proved that large energy savings are possible and that this is accompanied by a significant rise in comfort. Every year, the number of passive houses in Germany and Austria, not to mention Belgium, Northern Italy and Scandinavia increases by tens of percents.
Building passive houses within new housing development.
According to an ECN report in 2005, by using savings methods in homes and commercial and industrial buildings that have not been applied until now, the possible saving in 2020 will correspond to the energy consumption of one million households. However, if a new home is compared with a passive house, it is clear that even greater energy savings are possible. This means that if all new homes built after 2010 were based on the passive house model, a saving of 12 to 19 PJ would be possible. This corresponds to an annual reduction in CO2 emissions of 0.7 to 1.1 Mton.
Passive building is a specific method of constructing that focuses on a comfortable interior climate in the winter and summer. The building is constructed without a traditional central heating system and without active cooling. This means that the building has very good insulation and very little air leakage. The transfer of heat through not insulated construction components – so-called thermal bridges – are avoided as much as possible.
The optimum use of solar and residual heat is obtained through a combination of measures and design features. If the building faces south to within more or less 30°, warmth can enter on the sun-side of the building. For this, sufficient glass must be included in the south-facing wall to use the solar radiation to its fullest, while the insulation on the north-facing side must be optimum. A frequently heard complaint about homes overheating due to the south orientation can easily be avoided by simple exterior sunshades. No cooling system such as air-conditioning is needed. Energy savings are also achieved by an efficient low-temperature heating system and balanced ventilation with heat-exchanger – a ‘must’ in passive houses. The correct amount of insulation and ‘open facade’ can be established easily using the 'Passivhausprojektierungspaket', the Passive House Planning Package PHPP, available from the Passivhausinstitut in Darmstadt. Versions in various languages, amongst others a Dutch-Flemish and an English version of this are available. This can also be used to establish the required air-tightness of joints and the efficiency of the ventilation system.
Thanks to the measures described above, separate radiators are no longer needed and slight heating of the ventilation air is enough. In addition to the savings on CH installation costs, this reduces energy use for heating by a factor of four compared with the present standard. Compared with existing building methods, energy consumption for heating is even ten times lower. Building passive houses from scratch is the most obvious option but it is also possible to apply the concept in renovation, which actually represents the biggest potential saving.
At the moment, it is clear that mass-produced passive houses in the Netherlands are still more expensive than a traditionally built terraced house. A higher cost of up to seven percent is realistic for a single-family home in the first years. For potential buyers, this means a higher mortgage but, on the other hand, they can save on energy costs. And “green financing” might also be considered, resulting in lower mortgage repayments. Moreover, more and more banks are taking the total living expenses into consideration rather than just mortgage repayments. This means that with lower energy bills, higher mortgage repayments and therefore a higher mortgage are possible.
From the reactions of test-home residents in Deventer, it appears that they are very satisfied with their level of comfort. And certainly the very much lower energy bill, a natural gas consumption of approximately 120 m3 per year, was regarded as a major advantage. When more project developers and construction companies commit themselves to passive building, suppliers of such things as door and window frames, windows and doors and heating and ventilation systems will be able to produce even more cheaply, which will lead to a lower prices.
Information:
If you are interested in building a new house or renovating an existing property, please visit the website www.passivehouse.com/English/PassiveH.HTM
Contact:
Henk Kaan
ECN Energy in the Built Environment
Tel. +31 (0)224 - 56 46 89
kaan@remove-this-part-ecn.nl
