BUILD2PERFORM | PREVIEW D Dave Pearson District heating and cooling networks are a route to net zero, says Dave Pearson, director at Star Renewable Energy elivering net zero by 2050 will come down to many sectors. There is plenty going on in electricity generation and transport, which is great to see. Heat is now widely acknowledged as a key sector but, actually, very little progress is made. One could ponder why this is, but what about just getting it done? There are five sectors in heat, where actions can be taken. And we should try to involve cooling in these too they are after all, opposite sides of the same coin. From the easiest to the hardest, they are: New build low density: Ban gas boilers and dont allow direct electric this would alleviate potential stress on the grid. New build high density: Join district heating, if it exists. If it doesnt, pledge to do so, make the building district heating and cooling-ready (systems, temperatures and connections). In high-density areas for example, central London dont try and make the development a net-zero island as it makes adjacent retrofitting of energy networks harder with future gap sites. Older low density residential: Force utility companies to offer pay as you go heat contracts, then deploy heat pumps with local storage. This is the fastest way to grow our industry while acknowledging the reality that individual home owners wont stump up large amounts of cash, even when it offers a return on investment. There should also be some sort of bonus for selling a house that has been retrofitted. Older high density cities: Force all buildings T Louise Hamot We must tackle wholelife carbon emissions, says Louise Hamot, sustainability consultant at Elementa Consulting o meet our climate targets, industry needs to tackle a range of subjects such as energy storage; demand response; performance gap mitigation; calculation methodologies; occupants education; low-energy systems; and passive design measures. However, a deep dive into each subject wont be enough if we dont tackle whole-life carbon emissions. The industry has long focused on operational carbon meaning in-use energy emissions but has ignored emissions related to the rest of the life-cycle stages of buildings. Manufacturing and transportation, constructing, repairing and maintaining the building, and deconstructing and processing waste are all steps that create CO2 and other greenhouse gas emissions, referred to as embodied carbon. Another important factor is refrigerant to reduce emissions by 15% per annum (the real target ought to be net zero by 2030). If they cant, let them agree to join district heating when it arrives. When there are enough pledges to join in an area of a city, the investment will flow. Note that investment must be in the right sort of district energy: durable, fairly priced and clean. An obvious solution copies the Norwegian city of Drammen, which has river- or sea-sourced heat pumps. If the building doesnt maintain 15% per annum progress, serve a prohibition notice on use of equipment and remind owners the easiest solution is to pledge to join a district scheme. We call this a fairopoly, as everyone has to be fairly treated. Industrial: Many processes use steam when they could use hot water. Many processes simultaneously cool and heat. Join them up. If businesses wont make the investment, force them to agree to an energy supply agreement and let the commercial suppliers carry the technical investment. Underwrite the consumer default with some form of credit risk sharing. For those processes below 150oC, but above 85oC, heat pumps are emerging to do this. For applications above 150oC, we should plan for the sensible use of high-temperature fuels such as hydrogen, biogas, biomass, and energy from waste. It all begins with moving forward from gas and playing to stakeholders strengths and weaknesses. leakage, which has a high global warming potential and is often not considered. Engineers, architects, contractors and clients need to understand the key levers to mitigate whole-life carbon emissions and get the full picture of their environmental impact through robust life-cycle assessment as soon as possible. In order to achieve net zero for all buildings by 2050 all new buildings need to be net zero in operation by 2030. Leti and the UKGBC are running a consultation on the technical requirements for operational net zero for new buildings. They believe that the requirements must include an absolute energy meter target of 35 kwh.m-2 per year for residential, verification in-use, fossil fuel free on-site. Any energy consumption not met by onsite renewables should be met by investment in additional renewable capacity off-site. See www.leti.london for further details. 32 November 2019 www.cibsejournal.com CIBSE Nov19 pp31-32 Build2Perform.indd 32 25/10/2019 18:01