FAQ

Who we are, and why do we do what we do?

The Passive House Association of Ireland is a not-for-profit voluntary organisation whose aim is to promote the passive house concept in order to educate people and promote this low energy building standard. Its board comprises engineers, architects and academics who understand the standard and know that it offers an excellent solution for Ireland and its citizens. The association was formed in 2010 essentially by those who understand the potential for passive houses and as a voluntary non-commercial organisation simply want the truth to come out.

What is a “passive house”, and what makes it so special?

The “passive house“ (called the “Passivhaus” standard in German) standard is a science-based construction standard, created to all but eliminate the need for heating systems in buildings, meaning miniscule heating bills while simultaneously ensuring high comfort levels, indoor air quality and durability.

The Intergovernmental Panel on Climate Change’s 5th assessment report (2014) singled out the passive house standard as one of the key climate change mitigation options available for buildings. Endorsements don’t get much better than that.

The passive house standard was created by German and Swedish scientists and engineers 25 years ago, based on sound theoretical principles and on studying why earlier European and North American attempts at low energy building had failed. Since then its efficacy has been supported by masses of monitoring on everything from energy usage to indoor air quality. Attempts at low energy building have a long history of failing to deliver, with a performance gap existing between designed and actual energy use for a variety of reasons. And what’s the point investing in energy saving if it doesn’t actually perform?

Passive House is not about ‘toys on the roof’ such as solar panels or wind turbines, it about simple back-to-basic principles of insulation and draft-proofing.

How big a problem is this performance gap?

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Estimates vary greatly, but UK studies indicate that non domestic buildings may be consuming up to or more than twice the amount of energy predicted at design stage,  with dwellings seeing up to 100% higher heat loss than predicted. According to a source in SEAI, Irish homes that have received energy upgrade grants have seen performance gaps of 30 to 70%, with higher disparity in fuel poor households.

Passive houses on the other hand appear not to suffer from the performance gap. A review by English architect Mark Siddall of post occupancy heating data on 228 passive houses showed a mean heating consumption of 15.45 kWh/m2/yr – exactly in line with the space heating target for passive houses.

In essence, Passive Houses do exactly as it says on the tin in terms of energy demand. It can therefore be trusted 100% to deliver exactly what you expect from what is the biggest investment of your life.

Won’t making passive house mandatory cause construction costs to rise?

No, not in Ireland. Since 2011 new homes have been required to hit 60% energy reductions, which typically means a mid A3 BER – and in some cases even an A2. This means construction costs are now in passive house territory, so it’s questionable whether there’s any extra cost at all.

The latest issue of Passive House Plus magazine includes several examples which show Passive houses can be built at the same or even lower cost. A block-built passive house in Co Kildare was estimated by builder Pat Doran Construction, a CIF member, to have cost €20,000 less to build than the department’s own suggested specification from its regulatory impact analysis on the 2011 changes to Part L of building regulations. Cork-based builder Magner Homes – who favour traditional cavity wall construction state that passive houses cost no more than those constructed to the current building regulations and have built four passive houses for under €100 per sq ft. Indeed, CIF member Michael Bennett & Sons is currently offering 1160 sq ft three-bed semi-ds built to the passive house standard in Enniscorthy for an asking price of €170,000. The timber frame homes will have an estimated combined annual space heating and hot water cost of €200. The builder speaks of a real example of a customer who calculated the cost of heating their existing 1970s bungalow was €1850. They concluded that they simply couldn’t afford to buy any house other than a Passive house.

Ireland is probably one of the most cost effective places in the world to build to the Passive House standard because of our incredibly mild climate. Unlike central and northern-Europe where they get severely cold winters, or the north-eastern United States where they get cold winters and hot and humid summers, Ireland’s climate is extremely easy to deal with.

Furthermore, one of the largest manufacturers in the world of certified Passive House triple glazed windows – located in Ireland (Munster Joinery), make these windows for a tiny upcharge on normal windows.

Lastly, one of the ‘soft’ costs in building to the Passive House standard is the so-called ‘learning curve’ – again Ireland is in a great position in this respect having one of the largest pools in the world of trained designers and tradespersons to draw upon.

Is it true that passive houses don’t require heating systems?

No it’s not. They do require some active heating input at times – as well as domestic hot water, assuming you want to maintain basic hygiene standards. But they require much smaller heating systems, that are used less frequently. So innovative heating technology suppliers can breathe a sigh of relief, while energy suppliers could quite reasonably break out in a cold sweat. Passive House projects use just 1.5 litres of oil per year per square metre of floor area, this conveniently equates to €1 heating cost per square meter per year, so it’s incredibly easy to work out what your heating costs will be.

Are there any other benefits?

Absolutely. Where to start… What about the absurdly low heating bills, the higher comfort levels and the fact that taking a robust, fabric first approach locks in these benefits – and all the embodied carbon in construction – for generations to come, rather than less considered approaches with an over-reliance on technology with perhaps 20 year lifespans, and poorly detailed and executed construction approaches which may lead to costly repair and replacement work.

Above all else, Passive House is the highest comfort standard on the planet today. Unlike the national building standard in Ireland which assumes that heating is provided for just 8 hours per day, Passive House is modelled on the basis of 24 hours per day comfort. Comfort is assured in several ways including highly insulated glass which avoids temperature stratification or ‘cold pockets’ next to windows, complete elimination of drafts through proper air-sealing, absence of thermal bridges which creates warms edges to floors, tempered fresh air, improved sound insulation, comfortable humidity levels (around 50%) and high indoor air quality as exemplified by CO2 levels. There is no other building standard available globally right now which delivers this level of comfort.

But will it cause house prices to increase?

No. The market determines what price a given property’s worth. Developers won’t be able to charge extra for passive houses – even if they’re arguably worth more – unless buyers are willing to pay more. Even if that is the case, it’ll only be a question of how much more buyers are willing to pay for passive houses relative to other new homes, which are also legally obliged to be highly energy efficient (the average dwelling has to hit a mid A3 BER just to comply, and many apartments even have to hit A2).

What’s happening in Dun Laoghaire Rathdown?

Dun Laoghaire Rathdown Council issued a draft development plan which requires that all new houses are built to the passive house standard from 2016. This has caused an excellent debate around what sort of standard of housing our citizens should receive. There has been a large amount of opposition from the establishment to passive house being required from 2016. This is understandable from some industry sources who may not fully understand the passive house standard and while it will demand upskilling and training among some industry professionals it will also lead to an increase in quality compared to what housebuyers have been used to. Builders of quality houses have nothing to fear with the passive house standard.

What is extraordinary however is that the government department responsible for construction quality is objecting to higher standards. In any case passive houses won’t slow down construction. Passive house construction is often quicker because of the thorough design process involved, and because the buildings are often prefabricated.

Elsewhere, cities and districts are making this decision as they don’t want to be stuck with backstop national standards, but are implementing the passive house standard themselves. The Brussels Region has made the passive house standard mandatory for all buildings – both new build and retrofit from January 1st this year. The political capital of Europe has mandated this standard without any fuss whatsoever. Over 1 million square metres of passive house projects have been completed in Brussels to date, with many of those costing less than conventional construction. NYC is also moving rapidly in the direction of passive house, with a draft bill currently before the council proposing the adoption of this proven standard.

Over 30,000 buildings have been built to this standard in the world. People are voting with their actions and simply forging ahead and building higher than the national standards.

Is it really possible to have a Mercedes for Mondeo money?

Those who have experience in constructing to the passive house from the industry say yes.

Constructing to the passive house standard costs no more than constructing to the current building regulations according to builders who understand the standard and have experience in the area. They include Magner Homes in Cork who have built a number of houses and say that it costs no extra to build to the passive house standard compared with the building regulations. Kildare builder Pat Doran states that the most recent passive house he built was built for €20,000 less than a normal build. Finally, Michael Bennett Construction has A2 houses for sale in Enniscorthy for €170,000 which comply with the passive house standard and are covered by homebond.

The reason the costs are comparable with the current building regulations is that the levels of insulation are comparable, but what makes the largest difference is that the passive house is draft proof and has controlled ventilation. This means that for a little extra cost the heat losses associated with drafts are eliminated and the house has a very low heating demand.

They are also designed and planned using tried and tested software in order to ensure that they make maximum use of the available solar energy from the site and have the required level of insulation. Due to the high level of insulation and draught proofing, it is possible to ensure that even when refreshing the air in the house, little or no energy is lost.

Thus by designing properly upfront using tried and tested methodologies, this eliminates what is called the “performance gap” i.e. the difference between the planned and actual energy performance of a house.

Why don’t passive houses suffer from a performance gap?

Probably for several reasons. First of all, the buildings tend to almost run themselves. Writing in The Guardian , Lloyd Alter summed this up eloquently: “I suspect that people are happier in stupid houses, stupid buildings and stupid cities. Take a Passive house for example. These houses don’t have a whole lot of green gizmos; just a whole lot of insulation and carefully designed and placed high quality windows. The temperature doesn’t change much inside; a smart thermostat would be bored stupid.”

Secondly, the passive house software (PHPP) is designed specifically for low energy buildings. Ireland’s national methodology, DEAP, on the other hand, is used to generate BERs for everything from 100 year old buildings with no insulation, no central heating and leaky single glazing, to brand new experimental eco homes packed with insulation and green technology

Is passive house a threat to traditional construction methods?

Not in the slightest. The passive house standard is essentially open source and can be built using virtually any construction materials and methods. To date in Ireland, passive houses have been built using cavity wall construction, timber frame, steel frame, single leaf masonry with external insulation, structural insulated panels, insulating concrete formwork and even hempcrete. It’s just a question of careful detailing and workmanship to ensure continuity of insulation, airtightness and a seamless ventilation approach. The industry may not be aware of this yet, but the real threat to traditional construction surely exists in trying to meet stringent theoretical energy targets in building regulations without being informed by building-science based, quality assured approaches such as passive house. Throwing insulation and gadgetry at a building without due care for the consequences is a dangerously misguided approach.

Rather than being a threat, Passive House can actually help boost the construction sector in Ireland, something that the CIF and others don’t appear to fully appreciate. There are companies such as Cygnum Homes as well as Thermohouse and Ecohomes which actively export their whole-house solutions aboard – some as far as Japan.

Does it have export potential?

Some of Ireland’s biggest construction product manufacturers have passive house solutions, including Kingspan, Munster Joinery, Coillte, Xtratherm, Isover & Quinn. There’s a plethora of Irish build system and insulation manufacturers with passive house solutions, along with heat recovery ventilation systems, airtightness products and passive certified triple glazed windows. And we have over 300 certified passive house designers and counting, and the most certified passive house tradespeople of any country in the world. Irish companies are capitalising on the knowledge we have here and training people in China and in the States.

But how will I breathe in such an airtight house?

Better than in most houses, actually. Airtightness is a much misunderstood subject. It’s not about eliminating ventilation from buildings – it’s about removing unintended leakage through constructional inaccuracies. The mantra is build tight, ventilate right. Properly designed, installed and commissioned ventilation systems are inherent to passive houses – but worryingly not to the theoretically low energy buildings required by building regulations. And as a recent UK study has demonstrated, this is a foolish oversight. Higher energy efficiency scores in homes are associated with a statistically significant increase in asthma diagnoses,  because most energy efficiency efforts don’t come with fit-for-purpose ventilation strategies. Passive House projects are renowned for their superior air quality as measured by CO2 levels as well as humidity and radon, a known killer in Ireland. The average air change rate for Passive House projects is 10 air changes per day, with rates as high as 75 air changes per day in the kitchen and bathrooms, ensuring no lingering odours or condensation.

Living in a Passive House is the closest thing we have to living in the outdoor fresh air due to the mechanical ventilation which flushes the entire building 24 / 7. Plus, the ventilation is super quiet with a maximum of 25 decibels in living rooms (inaudible) and uses very little electricity (the same as a 40 Watt bulb for whole-house ventilation).

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