ROUND TABLE REVIEW 29


Performance, contractors “often bypass hidden details because they are diffi cult to execute.” He said the rigour expected in Passivhaus should be more commonplace; “ I don’t think it’s excusable to say it’s a bit diffi cult.” With a lack of buyer know-how, “progress must be industry-led,” said Storer, adding that “if left to old habits, our environmental standards will fail.” Roly Ward from sponsor Medite Smartply countered that consumer demand was a driver; “they demand low operational costs, longevity, and durability, even if they do not understand structural material physics.”


Onsite spec changes & feedback loops Delegates said that post-design changes onsite such as substituting some building elements, often due to availability issues, could hamper performance aims. Naomi Sadler said that in terms of building envelope and block specifi cation, “the reality onsite is that different conductivities and U-values are routinely mixed across different fl oors.” She added: “Unauthorised material changes are rampant, and while generic, freely available psi value details are helpful, they are legally invalidated if a site switches from aircrete blocks 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 said that for Newland, “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


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


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 he 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 around the Green Deal and more recently, ECO. While this focused more 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 force contractors to remedy them, even rebuilding structures. As Paul Christmas said, it will take some time before the mainstream standards begin to improve as a result of current training efforts. Simon Storer thought that it was more essential to “build true


ADF JUNE 2026


WWW.ARCHITECTSDATAFILE.CO.UK


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68