Evolving construction standards

The minimum standards that every building must meet are set out in the building regulations and explained in the Technical Guidance Documents. Of course, anyone who is building their own home will aim for a higher standard; indeed, many people in Ireland are adopting the Passive House standard.

While the building regulations represent the minimum standard and Passive House the 'gold' standard some people working in the construction industry use a middle standard. This middle standard is not defined anywhere but site practice shows us it is somewhere close to but not quite Passive House standard. This is interesting for us because the Chief Examiner for Construction Studies appears to have come to the same conclusion.

It is in the compulsory architectural drawing question (Q.1.) that the examiner specifies the details that he wishes the students to draw and recent questions have described external wall build-ups that contain 200mm of insulation. In both masonry and timber frame systems the detailing described contains 200mm of insulation. This places the details above the building regulations requirement (which is comfortably met using 150mm of a standard insulant) and below the Passive House standard which would typically require 300mm of a similar insulant.

I think the message in the exam questions is that designers/ builders should be aiming to do better than the minimum standards set out in the building regulations (but, perhaps, that specifying Passive House standard is a bridge too far).

This has created a bit of a challenge for Construction Studies teachers. There aren't any drawing details readily available that show 200mm of insulation. I know my textbook has 6 sets of details; two sets that meet building reg's and four that meet Passive House standard. The building reg's details show 150mm of insulation and the Passive House details show 300mm.

Not to worry...

This will be moot in a few years, when NZEB kicks in for dwellings the thermal transmittance values (U-values) for the building reg's will almost match Passive House and we'll be back to single level of insulation in details. I'm basing this assumption on the interim spec's for non-dwellings that was recently published. It shows Passive standard U-values (0.15W/m2a) for roofs and floors.

This will not only be helpful for us teachers; it will greatly improve the energy performance of the building stock and provide a better standard of thermal comfort in the home.