The following list of FAQs are those most often posed to MosArt. This will be expanded as more issues are raised concerning Passive Houses. Please note that the discussion below is aimed mostly at the general public and is therefore non-technical. All Passive House’s must be designed and tested in the specialist Passive House Planning Package (PHPP Software) by experienced Passive House experts.
What constitutes a Passive House according to MosArt?
If you do any internet searching on low energy housing you’ll come across multiple variations of terminology used which include the term ‘passive’ including ‘passive solar design’ and ‘passive stack ventilation’. When MosArt uses the term Passive House, we refer strictly to the standards and definitions set out by the Passivhaus Institut in Germany, including maximum space heating demand of 15kWh/m2/year, an airtightness level of 0.6 air changes per hour measured at 50 Pascal and a maximum primary energy use of 120 kWh/m2/year. Take care not to be confused by different terms – they clearly can have very different meanings.
What else can be built by using Passive House construction methods?
You can build apartment buildings, office blocks, schools, shops, factories, churches and even fire-stations (in other words, pretty much anything) can be built to the Passive House standard?
What is it like to live in a Passive House?
Great, Fantastic. A Passive House will provide a long-life, low maintenance, light-filled and whole-house high comfort with extraordinary low heating bills and excellent indoor air quality. Plus, you can feel very proud of yourself for dramatically reducing your carbon footprint. ‘Inwardly satisfied’ probably best sums it up!
Why should I bother building a Passive House?
In short, it makes no sense not to.  In the next 2 to 5 years, it is the ambition of the European Parliament that the Passive House would become the base standard of construction across the EU. Ireland is aiming to build to ‘Carbon-Neutral’ standards (yet to be defined precisely) by 2013, and that’s not too far away in terms of designing, planning and building a house. Our advice would be to think in the longer term about how energy efficient your project should be and, above all, don’t build a ‘dinosaur’ that will shortly be out of date regarding building standards
Can I be sure that my Passive House will ‘work’?
Yes, of course. It is essential, however, that the house has been properly designed in PHPP and then well-executed on-site achieving the required levels of airtightness and low thermal bridging. There are over 15,000 Passive House’s throughout Europe, providing very high levels of comfort in climates that are much colder than that of Ireland.
Can you open the windows in a Passive House?
Yes, of course you can. Even though a Passive House must be built to a high level of air-tightness, you can, if you wish, leave windows open whenever you want. People usually open windows in their homes to let fresh air in. You won’t feel the same need in a Passive House because the whole house is afforded with an abundance of fresh air 24/7 by the heat recovery ventilation system. Be aware that if you do leave windows or doors open in a Passive House during the cold seasons, then you will use more energy to keep the house warm, just as you would in a normal house. In the summer time, you can leave all the doors and windows open all day and all night if you wish – just as you might in a normal house.
What is the most challenging aspect of building a Passive House?
Difficult to say, but achieving the required level of airtightness is probably the most challenging aspect. So often it can happen that there is insufficient thought given to sealing difficult junctions or around service pipes. Ensure that all members of the construction team are fully aware of the need to achieve an airtight construction. Otherwise, inevitably the plumbing or electrical installers will innocently tear through membranes to fit their services. It is typically much easier to achieve the required level of airtightness when using a system-builder (whether concrete or timber frame), where most of the construction (including fitting and sealing of windows) is carried out in a controlled factory environment. Building a passive house using direct-labour is a risky option, as it gives huge room for error given that there is no single person or contractor responsible for the overall performance of the project.
What Building Energy Rating would a Passive House typically achieve?
This is project dependent. However, what will surprise many people is that a Passive House would not necessarily achieve an A1 or even A2 rating. Achieving such a high rating would typically require the use of renewable energy technologies for generation of electrical energy, whether by wind turbine or photovoltaic panels. Such renewable technologies are not necessarily or even typically found on Passive Houses. Remember this, a Passive House is really superb at saving energy for heating, but otherwise is quite similar to normal houses in terms of energy use for lighting, pumps, household appliances and the likes. It is not, therefore, to be considered a ‘zero-carbon’ house
Can an existing building be upgraded to the Passive House Standard?
Yes. SEI have recently launched (February 2009) ‘Guidelines for Upgrading Existing Dwellings in Ireland to the Passivhaus Standard’. A copy of these guidelines, which were co-drafted by MosArt, can be downloaded here
Is it possible to surpass the Passive House Standard?
Yes. It is indeed possible to build even better insulated houses than the Passive Houses standard, but it has been well proven that the cost of this is not economic in most instances (the law of diminishing returns applies). If renewable technologies such as a wind turbine and / or photovoltaic cells are used to generate electricity, then it is possible to have a ‘net-zero carbon’ home (where the amount of energy that you consume per year is equal to (or less than) the amount of energy that you produce on-site)
Do I need professional assistance to achieve a Passive House?
Yes. In order to achieve the Passive House standard, it is vital that the building design is tested and verified using the specialist PHPP software. At present there are relatively few consultants providing dedicated full passive house services in Ireland (MosArt being the first of these as far back as 2003).
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