Why quality matters

Posted by on Aug 14, 2015 in news | Comments Off on Why quality matters

The recent article by Cartwright Pickard Architects in the Architects Journal, entitled ‘Are our homes making people sick?’ is a welcome addition to the research on comfort within new homes. Their findings, based on internal monitoring of environmental conditions, energy use, occupant behaviour and build quality checks, should make uncomfortable reading for everyone in the sector. The performance gap noted in a number of other studies is sadly replicated here. Ventilation systems were found to be poorly installed, commissioned and maintained, and most of the properties overheated. Poor indoor air quality was found in most of the properties. 


However, I would have to take issue with the statement that ‘Improved energy efficiency in our homes may be having unintended consequences for occupants health’. The catalogue of issues highlighted in this research cannot really be described as unintended consequences, as they are entirely predictable, and the impact on occupant health is not down to energy efficiency. It is down to at best lacklustre MVHR design, shoddy installation, haphazard commissioning, and a toothless regulatory framework. The houses were all designed to meet Code for Sustainable Homes Levels 3 or 4, but it is evident that the checks in place within CfSH and Building Control assessments are incapable of preventing the issues Cartwright Pickard Architects uncovered. With the bonfire of regulations undertaken by the newly elected Government, it’s unlikely that this will improve in the short term.


The strategies proposed in the article, which include carefully considered heating and ventilation strategies, ensuring enough fresh air for occupants, fresh air supply in all habitable rooms, and balanced MHVR supply and extract rates, are all very sensible and could almost come from a Passivhaus introductory lecture. As Designers it’s clear to us how far from the UK norm Passivhaus requirements are. The photograph in the article, of flexible ductwork piled up in a heap within a presumably cold loftspace, reminiscent of the coils faced by Archibald Tuttle renegade heating engineer in Terry Gilliam’s ‘Brazil’, sums up all that is wrong with typical MVHR installations. Flexible ducts suffer high pressure losses and can easily be compressed, restricting airflow. If as it appears they are in a cold roof space a significant part of the heat recovered in the winter will be lost through them. Conversely, in the summer the heat built up within the loft space will be transferred into the ducts, exacerbating any overheating problem. In our role as Certifiers we require evidence that the MVHR system has been designed to the Passivhaus requirements, that appropriate components have been used and that the system has been commissioned correctly. An unbalanced system which does not meet the required flow rates will prevent a building being certified.


With the Code For Sustainable Homes, the Zero Carbon target and the Green Deal all scrapped, as the Passivhaus Trust have pointed out, there is now only one standard for those interested in low energy buildings. Passivhaus provides a robust methodology for the design installation and commissioning of MVHR systems, and as a result offers a real alternative to the catalogue of errors which is typical UK domestic ventilation.




Blog written by Karl Parsons