The following opinion piece was submitted by registered architect and Passivhaus Designer Mark Stephens on August 27th 2014 and is a continuation of the post ‘SI.9 and Part L | Are specialist ancillary certifiers needed? Part 1’
A critical aspect of heat loss in a building are through ‘Thermal Bridges’: A thermal (or cold) bridge is where heat can pass through from the outside of the building to inside through a material of higher conductivity. This normally occurs where the thermal insulation layer is penetrated or compromised. Thermal Bridge free design is one of the key requirements of Passivhaus design, construction and certification. (I have written a short Fact Sheet on Thermal Bridges HERE)
Thermal Bridges are also included in the calculation of transmission heat losses in the Dwelling Energy Assessment Procedure (DEAP) software. There are three default values available for ‘Thermal Bridging Factor’ (y) in DEAP (Appendix K in the DEAP Manual):
A default value of y = 0.15 W/m2 applies for all dwellings except the following:
• y = 0.08 W/m2 for new dwellings whose details conform with “Limiting Thermal Bridging and Air Infiltration — Acceptable Construction Details” (www.environ.ie) as referenced in Building Regulations 2008 and 2011 TGD L. This requires that the relevant drawings be signed off by the developer/builder, site engineer or architect.
(The third default value only applies to new dwellings where Building Regulations 2005 TGD L applies which I’m omitting here as we’re focussing on current Regulations.
Already we can see a conflict with S.I No.9 of 2014 and the sentence:
“This requires that the relevant drawings be signed off by the developer/builder, site engineer or architect.” needs to be amended to include references to S.I No.9 of 2014 which would be at Design stage the “Designer’ or at Completion stage, the Assigned or Ancillary Certifier.
The process currently is as follows (including for S.I No.9 of 2014):
1. In order to achieve the lower default value of 0.08 W/m2, The “Designer” is required to submit details that conform with “Limiting Thermal Bridging and Air Infiltration — Acceptable Construction Details”. The “Designer” currently takes responsibility for these details and effectively “signs” them off when submitting them to the BER Assessor
2. The “Designer” submits these “signed-off” details to the BER Assessor who then inputs the lower default value of 0.08 W/m2 into DEAP.
3. If the project is a new home offered for sale off plans, a provisional BER is issued based upon the design drawings and building specifications. This provisional BER is valid for a maximum of 2 years. When the home is completed, the provisional BER must be replaced by a final BER based on a survey of the completed home supported by the final drawings and building specifications which represent the home as constructed.
The SEAI have produced a guide to assist BER assessors with this survey of the completed home: DEAP Survey Guide
It should be noted that this survey is a visual inspection only and backed up only with supporting documentation in the form of photographs, drawings, specifications “Reports of works carried out in the dwelling from a supervising engineer or architect are acceptable as supporting evidence.”.
I will emphasise that no Part L compliance checks take place throughout the construction of a dwelling by the BER Assessor until he conducts the final survey on completion, which is a visual inspection only. The responsibility (again) rests with the Assigned Certifier who may not be suitably qualified in specialist aspects of Part L compliance.
As we have seen in the previous POST the Ancillary Certificates already exist for BER Assessors to be included within the S.I No.9 of 2014 process but what is missing is a clear instruction from SEAI that BER Assessors may also be requested to sign up to the “Code of Practice for Inspecting and Certifying Buildings and Works” in order to complete the Ancillary Completion Certificate (INCLUDING) Inspection.
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