Modern Building Services

10 MODERN BUILDING SERVICES NOVEMBER 2022 FEATURE HEATING N ow that all but a few die-hards accept the threat of climate change there is growing pressure on the building services industry to ‘do its bit’ in facing up to these challenges. Crucially, it is the expertise of the building services engineer that will ensure the various heating technologies available are applied in the most effective way. For example, the UK government’s Heat and Building Strategy includes a heating upgrade programme for residential applications that strongly promotes heat pumps, alongside other low carbon technologies. There is also scope tomake wider use of heat pumps in non-residential applications. However, we need to be realistic about the limitations of heat pumps and play to their strengths alongside other options. As a company that manufactures a range of heating products, we are well aware of the strengths and weaknesses of each technology. The appeal of heat pumps comes largely from their ability to provide heat with relatively low electricity consumption – ideally using electricity from renewable sources. There are limitations, though, to our renewable generation capacity, exacerbated by competition from other growing uses, such as electric vehicles. Capacity is also influenced by weather conditions. Figures released by the Department for Business, Energy and Industrial Strategy (BEIS) show that renewable production generated 40.2%of the electricity generated in the UK as of December 2020 but this fell to 37.3% in the second quarter of 2021. The decline was a result of lower wind speeds and fewer sun hours, leading to greater reliance on gas-fired power generation –much of it from highly inefficient power stations. In the first quarter of 2022 this contribution rose to 45.5%, the second highest quarterly share on record, yet still leaving a significant gap to be filled by other power generation technologies. A further limitation, familiar to many MBS readers, comes from the low water temperatures at which heat pumps operate if they are to deliver a sensible Coefficient of Performance (CoP). Increasing output temperatures serves to reduce CoP so getting the right balance is essential. One result of these lower water temperatures, compared to typical boiler outputs, is that existing heat emitters will not emit as much heat as they were designed to. This means that for heat pumps to be used as the sole source of space heating, heat emitters may need to be enlarged. In many (perhaps most) cases, the building’s thermal insulation will also need to be upgraded. The issue of lower flow temperatures also limits the potential for heat pumps in the industrial sector, as process heating typically requires high temperatures. With combustion remaining a key source of heating for many buildings, alongside other heating technologies, there is a great deal that manufacturers can do to mitigate associated environmental impact. Ian Dagley , General Manager at Hoval Ltd, discusses the opportunities. Meeting the challenges of low carbon heating