Mitcham Gasworks – Planning Success

St William’s Mitcham Gasworks development has been granted planning consent. The site will provide 579 homes in the London Borough of Merton and benefits from a comprehensive sustainability strategy which was discussed with both LB Merton and the GLA prior to submission. Our work addressed several key themes:

• Low carbon and future-proofed heat network – with no feasible sources of waste heat or external networks to connect to, it was clear the site would need heat pumps. However, determining what kind of heat pump and whether a role for secondary plant was warranted required careful thought. Air source heat pumps (80%) and gas boilers (20%) were ultimately proposed to balance CO₂ reductions and energy bills. Crucially, the Applicant reserves the ability to change this to 100% ASHPs if future factors dictate (e.g. changing regulations and/or fuel pricing);
• Strong circular economy principles – the site is designed with ordered adaptability and disassembly in mind to maximise material/product circularity. This includes an end-of-life strategy. A detailed construction waste plan was also devised;
• Identification of embodied carbon savings – the design accounted for the use of steel with a high recycled content and recycling of used concrete as fresh aggregate. Further opportunities will be explored post-planning;
• Overheating risk to noise-affected facades – passive measures were adopted to minimise overheating risk, however on facades adjacent to Western Avenue residents cannot rely on nighttime natural ventilation due to acoustic constraints. A similar constraint also applies to ground floor units due to security. Cooling via the MVHR system was therefore proposed in these locations. This is considered a more sustainable solution than installing a full CHW cooling network.