Why the design certifier and architect need third party building fabric assessments
The following opinion piece was submitted on 8th July 2014 by Joseph Little MRIAI, BArch, MScArch AEES. The author of this piece is an architect and building fabric consultant who carries out thermal bridge and hygrothermal risk assessments.
As a building fabric consultant I was recently asked by the architect and the builder-developer of a new commercial retrofit project whether a particular internal wall insulation strategy of a solid wall would work.
The architect in question felt that it must work when considered on a ‘first principles’ basis and the builder-developer agreed. Because they shared this view they asked me why they needed to do a formal hygrothermal risk evaluation at all. They hadn’t carried these out in the past and there was clearly a cost involved.
I explained that there is a world of difference between the intuition of a good, well-experienced, architect about something and a formal written appraisal carried out by an individual well-versed in construction and building physics using relevant standards and validated software carefully. It’s worth exploring the difference:
- First of all the appraisal is in writing with an identifiable author. It can be read, circulated and even criticised. It can be saved on the system. It naturally becomes part of the documentation that underwrites the decision making in the design process.
- The assessor of the higher risk assembly or junction must have professional indemnity insurance related to the assessment process. They are specialists – not architects on the ‘Clapham omnibus’.
- The need to make careful, objective judgments is not new – it existed long before S.I. 9: 2014 however the latter has brought this requirement into sharp focus. A report generated will inevitably find its way into the compliance paper trail.
- The architect and developer have mostly likely spent most of their careers constructing new buildings to much poorer insulation and airtightness standards than now required and it is only in recent times that traditional or historic buildings are being insulated at all. Greater levels of insulation and airtightness can effect hygrothermal risks, particularly in where older buildings are being retrofitted. There simply has not been enough construction work done at the new levels of insulation for new build or retrofit for the Profession and Industry to have learnt the lessons imposed by these more onerous standards. What then is an intuition or ‘first principles’ view based on?
The architect’s intuition about the IWI strategy may be right in which case the report is now available to support that view. It may be partially right in which case the report can advise one or more specifications substitutions that ensure a hygrothermally appropriate buildup result, or it may be very wrong for whatever reason: the report could then prevent a costly mistake.
In general when setting out services and proposing fees architects and design certifiers needs to widen the net when they consider what bodies of work need to be undertaken to prove that ‘yes, this building is 100% compliant in design’. The following two blog posts may be useful in aiding Architects and design certifiers in understanding: