NEWS
PASSIVE HOUSE+
Window-opening unreliable for ventilation, study finds By Kate De Selincourt
A
comparison between two pairs of households in Switzerland suggests that people do not reliably compensate for lack of mechanical ventilation with more window opening. The study was carried out by MVHR manufacturer Zehnder and presented at the 2021 International Passive House Conference by Bart Cremers. The four flats formed the ground and first floor of a single block, so weather, outdoor pollution, noise etc were identical for all. The ground floor flats had whole-house MVHR installed, while the upper floor relied on window opening for ventilation. Monitoring of window opening behaviour showed that over the course of a year, windows were open around the same amount of time during winter in all flats, and slightly more upstairs than downstairs in summer. However, while air quality in the flats with MVHR was consistently good (only one per cent of the time above 1,000 ppm CO2) the upstairs flats had much poorer air quality. Between 30 and 60 per cent of the time, CO2 levels were over 1,000 ppm. •
Draft development plan guidelines a “retrograde step”
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20 | passivehouseplus.ie | issue 39
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he Department of Housing has come under criticism for draft guidelines which would prevent local authorities from setting sustainable building targets for buildings as a planning condition, with the passive house standard and low carbon cement directly referenced. The draft document, Development Plans Guidelines for Planning Authorities, states that objectives dealing with specific issues governed by the Building Regulations or the Building Control Acts should not be included in development plans. “This includes objectives that refer, for example, to specific building standards or methods, such as NZEB, Passive House or Low Carbon Cement,” the document states. Over the past two decades, progressive local authorities have put sustainable building requirements into development plans to bypass building regulations. This began in 2005, when Fingal County Council introduced requirements in local area plans for 60 per cent reductions in energy use and CO2 emissions for new buildings along with 30 per cent renewable energy contribution. The predecessor to Passive House Plus magazine, Construct Ireland, was heavily involved in this initiative, and assisted Green Party councillors in other local authorities to introduce similar requirements, with successful impacts on the Dún Laoghaire-Rathdown County Development Plan and Dublin City Development Plan in 2006, and local area plans in Wicklow. These initiatives then led to unprecedented improvements to Part L of the building regulations when the Green Party entered government in 2007, including 40 per cent energy and CO2 reductions for new homes compared to 2002 levels and 10 kWh/ m2/yr of renewable energy in 2007, rising to
60 per cent energy and CO2 reductions in 2011. Passive House Plus editor Jeff Colley had first-hand involvement in this process, chairing a Green Party committee on buildings during the Green Party’s first tenure in government, and working with David Healy, a Green councillor in Fingal who worked on the policy from its inception, and who served as special policy advisor to the minister for the environment from 2007 to 2011. Commenting on the proposed text in the draft development plan guidelines, Healy said: “This proposal would be a retrograde step. I think it’s mistaken about what the legislation is for. The legislation is very wide. There isn’t anything in the planning legislation which says if something can be dealt with in the building regulations then you can’t do it via development plans. That just isn’t there.” According to Healy, the precedents with energy performance requirements in 2005 and 2006 bear testament to the value of this policy approach. “We know in practice that using the planning system to require more sustainable building has worked very successfully in the past. And in fact it has served as a model for improvements to the building regs. It would be a big mistake if we were to cut off that source of innovation at this stage.” Healy said that, because compliance with building regulations doesn’t have any regard to design decisions taken at the planning stage, it may cause overheating risks due to excessive passive solar gains, or conversely, significant increases in energy use arising from sub optimal orientation and inefficient building form. “The way that the building regulations are at the moment, they’re not covering all of the issues, because they’re not covering building form, they’re not covering solar gain,” he added. •