The case for making Passive House mandatory

There is a growing sense that passive house's time has come. Following on from the examples set by umpteen municipalities and local authorities in continental Europe, there are signs of public bodies in Ireland and the UK making the passive house standard mandatory. Jeff Colley describes the rapidly unfolding events and puts forward some key points to take note of as events unfold.

Dun Laoghaire-Rathdown County Council's decision to make the passive house standard mandatory for all new buildings in the county - albeit subject to public consultation - may prove to be the decisive breakthrough to make genuinely low energy building mainstream in Ireland - and may help to cajole the UK to keep up.


Much of the impressive recent growth in passive house in the UK has been driven by the public and non-profit sectors, with increasingly substantial passive projects such as social and affordable housing schemes, educational and civic buildings. In that context, Exeter County Council's recent decision to build its own housing to the passive house standard was welcome but not entirely surprising news. Meanwhile Kirklees Council are proposing to make passive house mandatory for development on the council's land, including when that land is sold.

Short of changing building regulations nationally, the initiatives taken by Exeter & Kirklees point the way to achievable passive house policy in the UK, for the foreseeable future. In a brazenly retrograde move, secretary of state for communities and local government Eric Pickles has prevented English local authorities from going further - with the other UK regions out of his reach thanks to devolution - by removing a clause in the Planning Act that permitted councils to set their own energy efficiency standards above those contained in building regulations. Essentially this means English councils can't impose a planning requirement that housing must be more energy efficient than the mediocre levels set out in Part L, though the renewable energy sector successfully lobbied for councils to retain the power to set renewable energy targets in planning.

The public consultation on Dun Laoghaire-Rath­down County Council's draft county development plan opens on 2 March, and the early signs indicate that the discussion will include some fallacies, unfounded assertions and hackneyed objections that mustn't distract us from the facts. The following list includes some key points to keep in mind as events unfold.

Passive house needn't cause construction cost increases

In Ireland this is already true, due to changes to Part L of the building regulations. It should also be the case in the UK from next year, when the mooted zero carbon homes deadline kicks in.

According to the Department of the Environ­ment, the average new Irish home that meets minimum compliance with Part L is expected to hit a calculated primary energy demand of 60 kWh/m2/yr1 - a mid A3 BER. That's an average across all house types. More compact dwelling types such as apartments tend to be in or around or below 50 kWh/m2/yr, which means an A2 BER. In urban and suburban local authorities, the development is likely to include an emphasis on more compact forms such as apartments and terraces so for many developers, an A2 is already a minimum requirement.

In fact designing to the passive house standard may reduce construction costs in many cases. Building regulations are completely disinterested in the form of a building. If I ask an architect to design a 200 sq m home for me, and I want a H-shaped bungalow upon which to land my helicopter, Part L's only concern is that I reduce the energy demand of that building by 60% compared to a poorly insulated H-shaped bungalow. If I had instead asked for a two-storey rectangular building, my 200 sq m would have a much tighter footprint, meaning considerably less surface area for roof, floor and walls per sq m of floor area, and substantially reduced spend on materials. It would also mean reduced heat loss, for the same reason.

There are other potentially significant construction cost savings too - such as those achieved by reducing the size of heating systems, given the tiny space heating loads of passive houses, and by avoiding the need for repair or replacement due to surface or interstitial condensation caused by less robust energy efficiency approaches. Economies of scale and increased competition are already bringing prices down, with a number of major construction brands coming into the passive house space, as many of the adverts in this and previous issues of Passive House Plus have demonstrated.

It's possible to build an expensive passive house too, of course. Some - but far from all- of the clients who build passive houses are willing and able to pay for the highest quality materials, and for other sustainability features (which mayor may not add cost). So a high spec passive house must be compared to the cost of a high spec A2/A3 house. Conversely, we have previously published examples of passive houses being built for in or around €1 00 per sq ft - prior to the benefits that economies of scale and increased competition will have as passive house becomes more common.

Higher construction costs won't necessarily cause house price rises

As any property economist worth their salt would agree, the market determines what property prices are acceptable. If a developer bids for land, and expects construction costs to be higher to satisfy a mandatory passive house target - even though that expectation is likely to be incorrect in Ireland given the A2/A3 BER requirement - they'll accordingly bid less for the land, causing land valuations to fall. It's therefore a question of total development costs remaining the same, but the ratio shifting more towards construction costs (meaning the creation of more jobs with high export potential, due to the innovative and international nature of passive house) and away from land costs, which means less money wasted on something as economically unproductive as land changing hands.

If buyers are willing to pay more for passive houses - as might seem reasonable, once public awareness of the benefits of passive house are more widespread - it'll just mean buyers being less likely to buy less efficient stock, unless the price is right. But existing homeowners needn't worry - there's much more existing stock on the market than new homes at any given time, meaning the effect would be spread across a greater pool of housing.

Its a moot point to argue that land prices in poorer areas may be too low to fall to absorb the extra construction costs of meeting passive house, as the same issue would apply to Part L. The logic of such thinking leads to dangerous places. If poorer areas are in need of regeneration, the solution is not to build substandard housing in those areas, consigning the occupants to needlessly high energy costs, fuel poverty risk and associated health risks, and stigmatisation as second class citizens.

Less robust current approaches will lead to building failures

Though Irish developers already have to build new homes to an A2 or A3 BER, neither the building regulations nor the Deap software (for generating BERs and demonstrating Part L conformity) give sufficient guidance to ensure that these buildings will perform properly. (Sadly, the government appears to be utterly incurious about the extent of this problem. Ten years after it was completed, the only study that the Irish state has ever commissioned to check how a representative sample of new homes complied with any parts of building regulations - the Energy Performance Survey of Irish Housing - remains unpublished. Yet its conclusions were utterly damning: only 1 of 52 homes complied with the 1997 version of Part L of the building regulations, and 19 out of 20 of a subset of those homes subject to combined thermography and pressure tests showed either missing insulation or cold bridging in contravention of the regs.

The same problems occur with the UK regulations. There are very real risks that new homes will therefore:

  • Threaten occupant health, due to poor indoor air quality;
  • Require repair/replacement work due to surface/interstitial condensation'
  • Consume far more energy than the BER indicates, and contribute needlessly to climate change;
  • Depreciate in value as a consequence of all of the above.

Most specifically, a peer-reviewed study printed recently in the Environment International journal demonstrates that in even moderately energy efficient homes in the UK, there's a statistically significant increase in doctor diagnosed asthma rates. The report puts this down to inadequate ventilation and heating. (This study is covered in greater detail in an opinion piece by the study's co-author Richard Sharpe in this issue).

Building regulations permit ventilation approaches that aren't proven to work in low energy buildings - such as the industry default of "hit and miss" manually closable holes in walls in living rooms, with mechanical extract in wet rooms - as Kate de Selincourt covered in exhaustive detail in issue 6 of Passive House Plus. These crude ventilation approaches are causing countless problems in recently built buildings - a fact that many local authorities are all too familiar with.

"The growth of passive house is already opening significant opportunities for construction product manufacturers, designers and tradespeople to sell goods and services into other markets."

Note that Dun Laoghaire-Rathdown's proposal does leave the door open for the consideration of appropriate alternatives to passive house. Here the burden of proof should be on the industry to submit evidence that stands up to scrutiny, to demonstrate that these alternatives deliver equivalent performance with regard to energy use, indoor air quality, and general build quality. In the case of ventilation as one constituent part of a hypothetical alternative approach, compelling evidence exists for some mechanical ventilation strategies, such as DCMEV, with monitoring studies supporting both indoor air quality and heat loss reduction claims.

In this case, the moderately good is the enemy of the excellent

Constructing new buildings to moderately good energy performance levels risks preventing them from ever achieving excellence. It's much harder to justify retrofitting that building than it is a very poor performing building. The paybacks won't be as compelling, the discomfort won't be as great. Perversely, one of the factors that may drive people to upgrade these buildings at considerable avoidable expense is the presence of surface and interstitial condensation arising from poorly conceived energy efficiency approaches.

The Construction Industry Federation has a long history of objecting to energy efficiency regulations

This extract, from a fully referenced article our deputy editor Lenny Antonelli wrote in issue nine volume five of our predecessor magazine Construct Ireland, bears repeating:

As far back as 1978, Construction Industry Federation managing director Thomas Reynolds argued against making insulation mandatory in new houses because "all builders are putting fibreglass into attics now anyway by choice ". He said that making it compulsory was an "entirely unrealistic and bureaucratic approach" that would "automatically hike up the price of houses". He also argued that the double-block cavity wall system was too expensive to be practical. 2

The CIF has made similar pronouncements over the years, warning Irish Independent readers in 2007 that the industry didn't have the "technical capacity" to meet government plans to mandate 40% energy reductions and renewable energy systems.

Earlier that year, the Irish Home Builders Association (IHBA) - a part of the CIF - objected to Dun Laoghaire-Rathdown County Council's plan to introduce 60% energy reductions for new buildings on the basis that the target was "not achievable", A 40% better standard was ultimately introduced.

So in that context it's unsurprising that IHBA& CIF director Hubert Fitzpatrick has objected to Dun Laoghaire-Rathdown's passive house policy, stating that the policy "will increase the cost of new build even further", and that if the policy goes ahead "there will be very few houses built in Dun Laoghaire-Rathdown next year". When the CIF objects to progressive policies like this ­against the better wishes of many of its members, including some with real expertise in delivering highly energy efficient buildings - we should remember their track record in these matters.

Passive house has international cachet, meaning export opportunities

Compared to passive house, Ireland and the UK's national methodologies for energy rating look decidedly parochial. This isn't to denigrate them ­it's simply that they were created solely. Terms like BERs, EPCs, Part L, SAP and DEAP mean nothing to a client in, say, Germany, America or Japan. Passive house, on the other hand, is demonstrably the world's leading low energy building standard, is growing exponentially and bound to become mainstream across much of the world as countries act to address climate change and energy security with low energy building approaches that actually work. This growth is already opening significant opportunities for construction product manufacturers, designers and tradespeople to sell goods and services into other markets. These opportunities are bound to continue to grow as more regions - and ultimately nations - turn to passive house as that elusive thing: a proven way of building genuinely low energy, robust, healthy buildings.

1 Note that this primary energy figure includes heating, hot water, ventilation and lighting, but not plug in electrical loads, which in low energy buildings tend to represent roughly half the total. The primary energy figures in the PH PP software instead include all energy usage. For this reason and several others, such as the fact that PHPP assumes consistent comfortable temperatures whereas the Irish and British national software tools assume the set temperatures are achieved for as little as eight hours a day, it's impossible to compare the tools.

2 Question of minimum levels of insulation generates some heat, Irish Times. p20, 18 August 1978


Colley, J. (2015) ‘The case for making passive house mandatory’, Passive House + , Issue 10 , pp. 88-89