CONTEXT 178 : DECEMBER 2023 33 BUILDINGS IN THE COUNTRYSIDE equipment has almost 3,000 products on it, from air, water and ground-source heat pumps to biomass systems. The scheme has a nod to fabric improvements by requiring any insulation improvement recommended by the EPC to be carried out first. Heat pumps are the microgeneration technology attracting most attention, but other technologies such as chip, pellet and log biomass systems can also attract capital grant funding, and they appear on the BUS list. Pondering the wider issues around microgeneration in such a sensitive location as Clovelly, I asked Rous about photovoltaics, and in particular solar slates, which are now being produced not so many miles away over the water in Wales. Some solar slates are the nearest I have seen to actual slate. How might this kind of product go down in Clovelly, where the roofscape is so important? Rous explained that the estate had been gradually replacing, repairing and refurbishing the roofs of the cottages over recent years, so replacing newly refurbished slate roofs with the solar equivalent would not make sense. The estate uses Delabole slate from Cornwall in preference to the significantly cheaper but often more brittle alternatives from Brazil or China. ‘I have an emotional attachment to the Delabole slate, the quality of the material and its gradations in colour,’ Rous says. ‘You can also find very good quality secondhand slates if the quarries’ order books are full.’ The challenge for listed building specialists Mitchell and Dickinson was to bring 107 17th-century buildings up to modern insulation standards and reduce energy bills, while preserving their character and beauty, with access by a steep, cobbled street. ‘On conservation grounds we couldn’t go for external insulative cladding,’ Rous says, ‘and the rooms are too small for internal cladding.’ Instead, sheep’swool loft insulation, bespoke draughtproofing and a secondary glazing system using plexiglass and magnetic tape were fitted. ‘If you keep a continuous low background heat, it minimises any damp problem,’ Rous says. ‘You also need to be careful about ventilation as we improve the draft-proofing of the cottages.’ The estate’s guidance encourages its tenants to ventilate the cottage for an hour a day. Other cost-effective approaches that the estate has looked at can also help with dampness. With positive input ventilation (PIV), a small fan draws tempered air from an attic space into the occupied space. This creates positive pressure, bringing in drier tempered air, and pushing or exfiltrating moist air out through the fabric, and reduces cold drafts. While PIV brings tempered air into the building, heat is still lost with the air replacement. This can be minimised with heat exchangers, such as those used in mechanical ventilation heat recovery units. These help to deal with ventilation while minimising heat loss, and can also be designed to remove moisture from the air. Whole house systems are an investment, needing plenty of space as well as air tightness, but single-sided units could be a way of treating particular areas in small dwellings. Possible future scenarios for Clovelly include village-wide systems such as growing biomass on the estate to heat networks, or large-scale wind turbines. Rous is open to these ideas, though doing so in an area of outstanding natural beauty, and with various administrative challenges, presents significant changes. On discussing longer-term planning to reach net zero, Rous looks for flexibility. ‘I prefer a Newtonian approach, with gradual improvements here and there, refining the processes as you go along. You learn and get a bit cleverer.’ We should remember that the impact of these small dwellings, and the small compact lifestyle that goes with them, is inherently less than many modern homes, just because of their footprint. And their fabric historically is already invested in carbon. Website www.clovelly.co.uk Dan Rigamonti is editor of Designing Buildings, a construction wiki that is supported by the IHBC. Building the harbour transformed the site into a fishing village in the middle ages (Photo: Clovelly estate) Opposite: The Clovelly estate has been gradually replacing, repairing and refurbishing the roofs of the cottages in recent years, using Delabole slate from Cornwall. (Photo: Jonathan Taylor)
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