By Simon Bones, founder and CEO of Genous

Developers are getting more savvy about how to incorporate retrofit principles into building refurbishment projects, but at Genous we still see mistakes being made. There are smarter ways of doing things that avoid these five common problems

1. Treating green principles as an afterthought in design

Conservation areas and listed buildings need planning for solar (and sometimes heat pumps), so if green approaches are being considered, thought needs to go into this in the application stage. Equally, there is benefit in incorporating and ‘selling’ the green credentials of a project to planning, especially where the development may otherwise be contentious.

Heat pumps also perform better with underfloor heating or oversized radiators; whether a heat pump is being incorporated into the development, consider optimising for a low flow temperature to reduce future upgrade costs.

Air-conditioning, heat pumps and MVHR all interact with each other and have competing plant requirements, so being clear on the strategy up-front here is key.

2. Not designing in the required locations and runs from the outset

Heat pumps normally need outdoor units, and these need careful placement for functionality, planning and noise considerations. Batteries also need the right placement for performance and fire risk reasons, while a re-roof (especially where high-end tiling solutions are being considered) can mean a great opportunity for in-roof solar, which puts less stress on the roof, looks better, saves tiling cost and performs similarly to on-roof (in comparison to solar roof tiles, which typically do not and have a much higher cost).

While a development needs the right placement of the external kit, thought also needs to go into pipe and cable runs, plant room location and layout, and other internal equipment. Even if a heat pump is not considered, think about adding a heat-pump compatible hot-water cylinder rather than a combi boiler, or there will be further upgrade costs if the customer does want to trade up in future.

3. Overdoing thermal improvements to fabric at the expense of technology

Modern building regs are good enough for anyone but the most dedicated Enerphit devotee. Don’t overdo the last 0.01 points of U-value as the savings won’t be worth the expense, whereas solar/battery/heat pump integrations will pay back far more quickly, and provide better green savings.

4. Not going to three-phase power

Above about 200sqm, think about three-phase power if an upgrade cost is sensible. Heat pumps use a lot of electricity, and the bigger the heat-load, the bigger that demand. Added to that, large properties tend to use a lot of electricity, especially if other tech is being added as part of the refurbishment, which typically will overwhelm an 80 or 100 amp single-phase supply.

Plus, if the project features off-street parking, a 22kW EV charger provides future-proofing for larger EVs, and allows full charging of even a large battery within typical off-peak tariff windows. Single-phase limits the client to 7kW, reducing convenience and increasing charge cost if charging is not optimised.

Optimising a property for three-phase is best done when electrics are being reviewed, as they often are in a full refurbishment. It’s not just about increasing supply but about how loads are balanced, so this is the best time to upgrade.

5. Not integrating cooling with renewables

Customers in high-end projects in particular can be pushy on air-conditioning but often don’t think through run-costs or the integration with renewables – and a/c is both expensive to run and not green.

Solar panels can reduce the heat transferred to a roof, while electricity generation matches typical a/c demand in a way that it doesn’t with heat pumps (which need most power in winter), allowing for both reduced run costs and a guilt-free, greener approach to a/c.

In properties with underfloor heating, consider running an air-to-water heat pumps on reverse mode (piping cool water through the floor) to take the edge of heat, or air-to-air pumps, with ducting or fan-coil units, to provide a/c in the summer and heating in the winter.

The theme running through all of these mistakes is early engagement with renewables and retrofit experts to design in an appropriate energy-efficiency retrofit plan at the outset of the project.