Passive House Design – Information

Declan Noonan of Declan Noonan & Associates is a certified Passive House Designer. Here he answers some questions about PassivHaus Standards.

Can you outline the background to the Passive House concept?

The passive house is a paradigm for the energy efficiency approach in the building sector. It is a building, which reduces the total energy requirement to such a small level that the technology to supply this energy is significantly simplified – it is not necessary to implement any conventional heating – and all heating (and cooling if necessary) can be supplied from a heat recovery ventilation system. The Passivhaus Standard saves 75 to 80% of the heating energy associated with building built to contemporary national building codes. That means that consumption is almost zero.

The requirement does not specify a particular construction method – this is very attractive to architects as it allows them to specify their own choice of appropriate building materials, components and systems. Is this an advantage? 

The advantage of this solution is that it is flexible. It is now possible to integrate Passivhaus Standards into different methods of construction. There are Passivhaus details available for masonry, precast concrete and timber frame construction methods, and for other new technologies such as structurally insulated panels (SIPs). Developers often have a certain preference for particular building methods because of building traditions, or landscape types. This together with the fact that the concept is freely available to everyone provides the opportunity for widespread use of the Passivhaus Standards for new buildings in almost all situations.

While it has been demonstrated that it can be achieved in new build construction, is it difficult to meet in the refurbishment of existing buildings?

The technology of the passive house can, of course, also be used in the refurbishment of existing buildings. It will reduce the heating energy requirement of an old building by at least a factor of 4.

An optimised building envelope, an specifically, minimal air infiltration and thermal bridging are integral to achieving the standard. Methods for their reduction are relatively unfamiliar to the Irish construction industry. Has the standard and the requirement for post construction  testing been shown to improve design and construction in Germany?

It definitely has. It is not difficult to construct an airtight and thermal bridge free envelope – although you have to learn how to achieve it. Good craftsmen learn these skills during their first passive house project. These skills are not only useful for building passive houses, but for all buildings.

The PI has developed a package of support to designers including the Passivhaus Planning Package (PHPP). Are those appropriate for use in Central Europe?

The PHPP was especially designed to be a reliable tool for the design of buildings with a very low heating energy requirement. Conventional calculation methods do not work well for these conditions – the reason being that there are many assumptions made for user behaviour, internal heat loads and ventilation which are not so important for buildings with mediocre insulation (simply because their energy flow is small) but which are significant for the Passivhaus Standard. Therefore, the very first projects were designed with a sophisticated dynamical simulation programme, which the institute still uses if new concepts come in. 

THE PHPP method was then developed based on the results of the dynamical simulation. This method has been evaluated by its use in more than 300 buildings and has proven itself to be very reliable. It is not only a method for calculating the annual heat requirement and the primary energy demand – it provides the design values for the ventilation an heating ans if necessary for cooling systems.s The 2007 version includes climatic data for all of Europe, and lots of data from America and Asia too.

At this moment in time, buildings designed, constructed, tested and verified with the PHPP 2007 to meet the Passivhaus Standard can be certified by the PI in Germany or a certifying body approved by the PI. Are there plans for a certifying body in Ireland?

There are already negotiations with partners in Ireland. Quality assurance testing will be undertaken with specific regional climatic data and building traditions. 

Across the EU, the Energy Performance of Buildings Directive (EPBD) is being implemented with the development of national energy assessment methodologies (as is the case in Ireland with the DEAP methodology for indicating dwelling compliance with TGD Part L). Many countries have indicated timescales for moving forward towards national energy standards stricter than the Passivhaus Standard. Will national methodologies in the future become more sophisticates and capable of calculating low energy/low carbon buildings?

It is a difficult issue – how to define the mandatory standard of new buildings with goals that might be set for 2015 or 2020 – because we do not know what technological development that will take place during the next ten years. But unless there are revolutionary new developments it does not make any sense to require a stricter mandatory standard that the Passivhaus. Of course it is possible to build such houses, but they are not economically viable. The Passivhaus Standard is a cost effective solution.

One dwelling has been constructed and certified as meeting the Passivhaus Standard in Ireland. The dwelling is currently being monitored by UCD ERG to confirm its energy use and CO2 emissions. Preliminary data indicates that considerable savings are being achieved. The recent amendment to Building Regulations TGD Part L for Dwellings aims to reduce both energy use and CO2 emissions by 40%. However, changes in design and construction practices, building control inspection and post construction testing will be necessary to deliver actual savings. Has the monitoring of buildings certified to Passivhaus Standard confirmed actual savings in energy use?

What market strategy might be successful for Passivhaus to succeed in Ireland?

To introduce the Pasivhaus Standard we need to start with well designed demonstration projects all around the country. These houses should be open to the public with an information campaign for investors. Details need to be shown to architects and contractors. An education programme informing designers how to design and construct  a really airtight and thermal bridge free building, how to integrate a heat recovery ventilation system, why high performance windows provide a better indoor thermal comfort could be run. None of these things are difficult, but they are somewhat different from what designers are familiar with.

The Passivhaus Standard has been applied to new build and refurbishment of residential, commercial and industrial buildings in Europe. Where do you see the greatest potential for future Passivhaus market in Europe?

In the future, in at least 10 to 15 years, the whole building market will only offer passive house components all around Europe and for both new construction and refurbishment. This is simply because these high performance products will not be much more expensive than those normally used. They already pay back in the present, offer significantly better indoor climate and air quality, and they solve the problem of high energy process as well as the challenge to mitigate climate change. 

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