28
ROUND TABLE REVIEW
CHAIR
James Parker, Managing Editor, Architects’ Datafi le/ Housebuilder & Developer
ATTENDEES • Dr Jaydeep Bhadra, Domestic Sector Technical Manager, CIBSE
• Richard Lupo, Managing Director, Shift Environment • Prof Lubo Jankovic, Professor of Energy and Buildings, Energy House Labs, University of Salford
• Jonathan Cheng, Sustainability Manager, Dandara • Dan Jestico, Director, Sustainable Design, Savills • Mike Leonard, Visiting Professor, Birmingham City University, Centre for Future Homes
• Abigail Woolf, Senior Energy and Carbon Advisor, UKGBC
• Greg Jones, Residential Sector Lead, Hoare Lea • Ian Pritchett, Co-Founder, Greencore Housing
SPONSORS’ ATTENDEES • Mike Jones, National Specifi cation Manager, Garo Electric
• Nathan Tranter, Head of Heating, Panasonic Heating & Ventilation
• Ronny Reeves, Business Development Director, WMS • Ellis Maginn, Technical, Design & Specifi cation Solutions, Recoup Energy Solutions
• Larry Soper, Technical Services Manager, Envirovent
as the target measure, not a percentage, and exemptions to the 40% area functional requirement. Some suggested that this would need to be further revised before the introduction of the Home Energy Model, due to eventually replace SAP, which is expected in summer 2026. Delegates said the lack of battery storage requirement was a major missed opportunity for bringing resilience in an uncertain energy security context, including the ongoing Iran confl ict. The two-year ‘dual running period’ of SAP 10.3 alongside HEM was a cause for concern, as were inaccurate assumptions on energy and water consumption built into HEM (in comparison with SAP). Further issues were highlighted around the ‘notional building’ model such as using the ‘target emissions rate’ (TER) rather than the more detailed ‘energy use intensity’ (EUI) metric. The chair asked whether HEM as it stood needed to be evolved further to be fully workable for the industry. Could incorrect assumptions lead to more performance gaps between as-designed and as-built homes? Jonathan Cheng of housebuilder Dandara said that while the Standard had brought some clarity, “the uncertainty is around the SAP software side of things; that’s the next step in terms of giving us answers around forms of heating and hot water generation.” He said that in the meantime, as the industry waits for HEM, Dandara had been “preparing different scenarios.” While it will be introduced as an iterative process, it was
currently fl awed, said attendees. Ian Pritchett of Greencore Homes said it was “the elephant in the room.” While the nascent software will “learn over time,” he said it is “likely to be a little inaccurate and underestimate unregulated energy, and could lull us all into a false sense of security, thinking we’re hitting low energy use intensities.”
HEM is currently thought to assume people shower around 2.5 times per week – reportedly based on old data from one manufacturer. Ellis Maginn of sponsor Recoup commented: “Occupancy and frequency of showering are absolutely key for [carbon] impact. The HEM model doesn’t look representative currently, even less so than SAP, which we would argue wasn’t fully realistic based on a lot of studies.” He criticised the “narrative” from the Department for Energy Security and Net Zero, who “said that they’ve been speaking with industry” but from Recoup, plus competitors’ Showersave and Triton’s perspective, they “have not had any engagement.” He said “it feels like the user point of view has been overlooked.” Jaydeep Bhadra, representing CIBSE, said they had raised concerns in the consultation around “asking people to put MVHR in, when the notional building doesn’t account for air permeability or air tightness,” and it should be closer to Passivhaus. Larry Soper from sponsor Envirovent focused minds on the performance gap, saying that in the case of air permeability, the designed and as-built “can be two totally different things.” He said it is “key” that if MVHR is being included and the permeability is below three, the as-built “needs to be as close to that as possible.” Continued use of SAP 10.3 could create another possible mismatch between overall design and built performance, as the minimum Seasonal Coeffi cient of Performance of heat pumps in SAP is 2.5, which is far below the potential of current units. Abigail Woolf of UKGBC and others said the 40% of ground
fl oor area PV requirement in the ‘notional building’ was an obstacle which was hampering specifi cation of innovative solutions. She said that putting the functional PV limits “slightly less” than the notional limits would be a possible remedy to incentivise “energy demand management or heat pump effi ciency.” Dan Jestico of Savills said that further clarity was needed, based on the chair’s question around the ambiguity of including a “reasonable” amount of PV as the criteria for whether it is viable on a development within the Standard, with the loophole of no PV if this isn’t possible. “What is deemed an acceptable level of mitigation or compliance is the kind of detail that everyone will be looking at.” He added: “If what is a reasonable amount is kilowatt hour production, and you can’t get enough PV to get over a certain threshold, I presume that will be the exemption, rather than the 40% fi gure.”
Solutions & sponsors’ question time The second half of the debate was given over to exploring fi ve crucial areas of specifi cation which were represented by our sponsors - namely electricity supply resilience, air source heat pumps (ASHPs), underfl oor heating (UFH), wastewater heat recovery (WWHR), and ventilation. All asked pertinent questions to the group, including around the resilience challenges on electricity.
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