The role of the SAP Assessor is gradually changing within the self build lifecycle.
Ten years ago when I started my first self build my architect did my SAP calculations and if I’m honest I was barely aware of them and their potential consequences. Fortunately for me, that particular version of SAP was a lot less stringent than SAP 10. Firstly this meant that because the calculations were a lot less involved the architect was happy to include this as part of their work. Secondly, as long as my dwelling was well built and insulated (which it was using a timber frame/SIP approach) it was almost a given that it would achieve its SAP through the airtightness test. The real risk as I discovered was shoddy workmanship by the various sub contractors (which I will address in a future blog post) but after a comprehensive snagging phase accreditation was duly achieved.
On-site with the current self build
One year ago when I started my current self build, my architect and I put a lot of thought into the design process to create a high performance, energy efficient, beautiful home. We were conscious of the more stringent standards withing SAP 10, however we didn’t work through the design in tandem with a SAP Assessor. A large part of the design was looking at what materials, construction methods and renewals I was going to utilise, and these decisions fed into the SAP ‘At Design’ stage, however the process wasn’t fully integrated and as a result my architect made a lot of the decisions around materials. A good example would be the types of insulation and thickness for my roof and floor, which he passed onto the SAP Consultants that we engaged at the end of the Building Regulation drawings. As a result of specifying the highest spec materials and a combination of renewables we easily passed our SAP. Now maybe I should have been more across the detail but unless you decide to become a SAP Assessor and know what you’re looking for its easily missed! The insulation he specified was the highest spec and therefore now I’m coming to install it easily the most expensive! With the cost of materials throughout the build so high currently I am keen to save money where I can and with hindsight could have potentially saved in this area without too much degradation in the quality of the insulation and ensuring accreditation was still achieved.
When the next version of SAP comes in, currently scheduled for 2025 which will require buildings to be a further 75% more efficient (as SAP continues to evolve and encourage future buildings to be carbon neutral), I believe that the SAP Assessor will best be used as a consultant, brought in at the start of the design process, working alongside the architect from the start. This partnership will be vital to ensure that not only is the dwelling, beautiful and well constructed, but that that it performs to these new standards as we all work to protect our environment. Working in this way with the SAP Assessor performing a variety of calculations to look at how the new standards can be achieved while still focusing on budget. In effect just like the architect presents the client with a number of decisions around space and quality vs budget, an effective SAP Assessor will do the same, presenting the client with a series of options and costings that will allow them to achieve accreditation while focusing firmly on costs. The relationship and role of the SAP Assessor will therefore evolve from somewhat of a tick box exercise 10 years ago to something much more consultative where early involvement, analysis and planning will result in an optimal build at an optimal price.