40 KEEPING FABRIC FIRST IN FUTURE HOMES STANDARD COMPLIANCE ROUND TABLE REVIEW
SOLUTIONS FOR GETTING FUTURE HOMES’ FABRIC RIGHT As well as exploring the challenges of keeping fabric to the forefront, delegates looked at solutions including data transparency, onsite checks, and embodied carbon
to alternatives.” Chris Pears-Ryding from event sponsor and block supplier Tarmac said it was important to “motivate busy site teams” to ensure that demand was managed appropriately, to avoid mixing: “Compliance data needs to offer direct operational advantages, for example, verifying material volumes via digital photo logs to power automated demand forecasting.”
Rob East assured delegates that for Newland Homes, “mixing block types within a single storey is an absolute no-no. If a shortage occurs, we halt construction at a defi ned plot boundary and revise the compliance calculations.” He said that aircrete blocks “vary signifi cantly by manufacturer, so our buying team identifi es available options, and we run SAP calculations based on the worst-case scenario data to ensure a fail-safe compliance route.” His fi rm has extended its spec to a 125 mm blown-insulation fi lled cavity, “which fi lls structural gaps more reliably than partial-fi ll rigid boards.” He added that quality control has been tightened up – Newland Homes has reduced air tightness from seven “down to a consistent fi ve.” While he said going to 4.5 would be “comfortable,” dropping down to 3.0 becomes “signifi cantly more demanding on trades and depends heavily on house geometry.” Delegates pointed to the importance of setting up ‘feedback loops’ from developers on the true thermal performance of compliant homes to help grow best practice. Dr. Marina Toupouzi of the University of Oxford said a true fabric-fi rst approach “must prioritise holistic thermal comfort and structural resilience against future cooling demands, not just heating costs.” And “active evidence” needed to form those feedback loops to “instruct installers onsite about structural failures. Currently, we compile data without learning from construction mistakes.”
Another reason that performance may not match expectations was around default values being applied to fabric designs, however, plus a lack of expertise in the sector, however this was exacerbated by certain product substitutions, said delegates. Jon Ducker explained the example of substituting a specifi ed 0.15 W/mK aircrete block
with a dense aggregate block, which “signifi cantly increases the psi value.” He added: “If this goes unrecorded, the completed home will seriously underperform. If it is caught late, the house will fail its compliance test.”
And Ducker asserted that FEES would not protect against this,
being a “holistic score determined by walls, roofs, fl oors, windows, air tightness, thermal mass, and ventilation. You cannot compensate for a poor fabric design by adding solar PV; individual window variances cause minor swings, but party wall junctions and lintels can cause massive heat loss if developers drop down to poor regulatory default values.” Naomi Sadler added: “This is where progressive companies utilising intelligent vapour membranes will succeed. BREL requires visual evidence of explicit membrane overlaps, which manages interstitial condensation risks while securing airtightness.” She said that standard site practices, “like incomplete mortar dabs behind plasterboard or unsealed fl oor joist penetrations,” are primary sources of major air leakage.
Solving the skills and competence gap Paul Christmas of external wall association INCA described the training initiatives underway to increase rigour and professionalism of installations, in the wake of well-publicised failures of external wall insulation following ECO projects. While he was focused particularly on the huge domestic retrofi t challenge, tackling the inconsistency within training that he pinpointed was a vital part of the new, more belt-and-braces culture permeating across the industry, which will slowly rebuild consumer trust. Paul accepted that the standard curriculum still “completely omits proper installation detailing,” and even structural engineers, according Naomi Sadler, “routinely alter site details without understanding the impact on psi values or fi re safety compliance.” She said that further education colleges “refuse to update their curricula,” so it’s left to enlightened consultancy to spot failures and
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