Why is ventilation of new-builds not adequately covered by regulations?

I have just read your article about the importance of ventilation in preventing condensation. I write as a member of Shankill Action for a Green Earth (Sage).

We have come to learn that ventilation is not adequately covered in the building regulations and as a result new-build, A-rated houses cannot work as genuine A-rated houses because the windows cannot be kept closed, especially in cold weather. One person I met at a seminar said that his A-rated house was freezing cold.

Why do the building regulations not include controlled ventilation, for example heat exchange?

Also, I have heard several times of people who have had ceilings or roofs collapse due to lack of ventilation or damaged ventilation causing condensation and rotten timbers.

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We feel that we cannot advise on retrofits until this issue is sorted out. We need to reinstate building inspectors with real powers.

The building regulations provide a set of rules to ensure the health and security of occupants as well as safeguarding the fabric of buildings. These regulations are the legal requirement which builders and developers must abide by. The regulations are backed up by a set of technical guidance documents (TGDs) that guide designers and constructors along paths in which the regulations might be achieved.

The TGDs are updated from time to time as materials, techniques or targets change. Part L, for example, which covers the energy efficiency of buildings, has been altered over several recent iterations to reflect climate change targets. However, part F covering ventilation has struggled to catch up despite having been revised four times since its introduction in 1991.

The current 2019 version still does not fully address the ethos of the actual regulation which directs that, “adequate and effective means of ventilation shall be provided for people in buildings” and that, “this shall be achieved by (a) limiting the moisture content of the air within the building so that it does not contribute to condensation and mould growth, and (b) limiting the concentration of harmful pollutants in the air within the building.”

Accordingly, holes in walls are still largely utilised as prima facie evidence of compliance despite the resultant energy inefficiency that has to be adjusted in the DEAP software which assesses part L compliance – energy efficiency.

Regulations are all well and good but, as you point out, in practice are rarely fully achieved. In my own jaundiced view this is mainly due to the complexity of the other parts of the regulations – A to M covering everything from structure to access and facilities for the disabled – which can cause some designers difficulty, resulting in the kind of conflicts and failures you describe.

The root cause of ceilings collapsing, and wet timbers is usually due to a lack of a vapour control layer allowing excessive condensation to form in the insulation or cold roof timbers above, not necessarily the lack of ventilation which of course could help.

Pathways to improving the regulations are complicated by the presence of a large number of vested interests as well as the lack of a holistic understanding from designers on how they might proceed together. This is coupled with a lack of understanding by many occupants about how they might best live in a new home. Unfortunately, homes don’t come with a user manual, something I have promoted for many years.

Currently, the TGDs are in somewhat of a flux due to the widespread lack of empirical data to steer new amendments. Certainly, ventilation is a hot topic that requires better guidance, at a remove from multiple complex systems that are probably unnecessary in a thermally efficient fabric.

Rather, guidance should steer people towards simple systems that ensure good healthy air quality with minimal complications, minimal investment and low running costs. Many passive homes don’t figure in guidance simply because of the legacy of mechanical engineers training on high output systems which are no longer relevant when we have great insulation and airtightness.

Exhaust air heat pump systems available from several companies are often overlooked simply because they seem to an engineer to be too good to be true but are often the simple fix needed when good fabric upgrades are required. They are also often ideal solutions for “bungalow bliss” type homes.

You suggest we should invest in inspectors with more powers. However, I don’t think in the current legislative climate where developers are struggling to build at affordable prices that will work, rather, I would suggest that we drive alternative methods to the TGDs that achieve compliance and compliment better economy of investment and improved user experience.

Understanding how to advise on retrofits is a very mixed church. Not only are there a myriad of building types but the original implementation, maintenance and ultimate condition vary immensely so it’s not a one-stop-shop approach that will in the end be viable, rather it’s a holistic understanding of the presenting factors that will provide you with the correct approach to individual retrofits. Unless that happens, we will be retrofitting the retrofits as unforeseen consequences arise.

When advising people about retrofits remember it’s the occupants who will suffer if the basic reasons for health and safety are not met whatever about the health of the building.

Also, remember there are a lot of sales-led organisations eager to profit from the seemingly vast sums in grants now available, so my advice is to minimise the interventions, get good professional independent advice and trust your intuition.

Fergus Merriman is a chartered building surveyor and a member of the Society of Chartered Surveyors Ireland

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