As it is now, Part L misses obvious tricks, has loopholes that make it ineffective in important areas and does nothing to prevent super-insulated homes from turning into ovens

One upshot of the political turmoil in Westminster has been further delay in the publication of the long-awaited consultation document on changes to Part L of the Building Regulations. This is a concern since reportedly it will include useful proposals, as well as some pitfalls.

The first of the good ideas that has been mooted is a requirement for “consequential improvement” in existing homes – that is, reasonable, cost-effective changes to make a home more energy-efficient if it is substantially altered through refurbishment, extension or a loft conversion.

This is encouraging, although the history of this issue does not fill me with confidence that common sense will prevail. In the consultation on Part L in 2006, consequential improvements were supported by more than 80% of respondents, and were welcomed as cost-effective and proportionate: householders would be required to invest no more than 10% of the value of the building work, up to a maximum of £3,000, on energy efficiency improvements to the building.

The story is that in 2005 a new minister arrived at the communities department to find these Part L regulations on her desk. After the briefest of discussions (during which I fear the environmental advantages were probably never even considered), consequential improvements were thrown out on “social cost” grounds.

I sincerely hope history will not repeat itself. There is no good reason why, if explained and presented properly, householders should object to making reasonable energy-efficiency improvements to their buildings – especially as they will be the ones to benefit most from lower fuel bills.

However, having such a regulation for consequential improvements will do little if the wording and guidance is as loose as the regulation we have for the non-domestic sector. This is the second aspect I am keeping under close review.

At the moment, Approved Document L2B provides a sneaky get out of jail free card. The requirement for consequential improvements in the commercial property sector (for refurbishment of buildings larger than 1,000m2) only applies in so far as it is “technically, functionally and economically feasible”. A quick note from a compliant architect or building surveyor and you can get away with doing nothing – my guess is that this regulation is not being consistently applied or implemented.

There is one notable zero-carbon development where the summertime temperatures in bedrooms are reported to reach more than 40ºC

I am a strong supporter of a regulation for consequential improvements, but government must also address the definition so that such a loophole in the guidance cannot be exploited as it is now.

Another area of interest to me is something I hear will not be in the new regulations – but surely should be. The rumour is that overheating in the summer will not need to be checked robustly under Part L. In the same way that the regulations do not try to set minimum standards for air temperature or air quality, so they will not set maximum limits on how much a building can overheat.

If this is true, we face a serious health issue. For we are designing such thermally efficient buildings, with ultra-low U values and ultra-high airtightness, that solar gains can push internal temperatures far too high. There is one notable zero-carbon development where the summertime temperatures in bedrooms are reported to reach more than 40ºC! Global warming will only worsen the situation.

Without more robust checks within SAP and SBEM, we run the risk of swapping the problem of winter hypothermia among the fuel-poor for the risk of heat stress.

The alternative is the huge cost and environmentally disastrous retrofitting of air-conditioning.

So bring on Part L. We may have lost every minister and junior minister with any history or background understanding of the issues, but the new arrivals must give this their full and considered attention.