Sustain IARA –  the Inkerman Area Residents Association sustainability group. Information sheet on some local houses.

Prepared for the street party on 8 July 2023 when the first three of these houses kindly hosted visits by interested people . We may create videos of these visits and post them here.

SustainIARA is a sub-group to implement and share knowledge of Climate mitigation and resilience, Sustainable and Regenerative action in the Inkerman Area.  For example:  – Climate / carbon / energy /PV – Travel / Car pool / shared bikes, cars and other vehicles / EV charging – Public realm / Parklets / seating – Recycling / Reuse / exchange – Buildings / insulation / retrofit / grants  – Shopping locally / eco-deliveries – Biodiversity


Jon C in  Grafton Rd

About three years ago we installed eight solar panels on our roof which runs east to west and therefore is sub optimal plus a lithium battery.

Theoretical maximum is 3.8 kW. Cloudy day give 1 kW.  We are plugged into Octopus who are good.

It cost £7000 and at the time there was a projected payback period of five years but with the increase in the price of electricity it’s probably 3 1/2 years now.

It was installed by a firm through the London Council scheme but that firm has gone bust.

No subsidies and unfortunately we just missed out on the fact that the VAT was removed from solar panels.

We also missed the opportunity of installing a heat pump. We have good insulation in the loft but single glazing and no particular wall installation.

Rafe and Sophie  in Inkerman Rd


About 80mm of internal insulation was added to the old solid brick walls. The product was called Diathonite, a mixture of cork, lime and clay. This was then skimmed with lime plaster and then painted with a breathable paint, all so the wall could ‘breathe’ and the moisture could escape from the old brickwork. The builders chipped off the old plaster, gaining about 30mm, and so the new insulation took up about 50mm of space on the inside. Because we also added more storage and better desk space, we didn’t feel the reduction in space. In fact, it felt bigger after the works were done. 

We used 50mm PIR insulation (eg kingspan) above the rafters, and 100mm wood fibre between the rafters. We wanted to use regenerative materials for all the insulation, but we needed the thin PIR insulation to keep the build-up low as we were not allowed to increase the height of the roof, and we wanted to keep the existing rafters. 

As we have replaced the timber floors, the builders insulated the floor by putting mineral wool insulation between the joists. The kitchen area has a concrete slab, and we put PIR insulation above the concrete slab, below the flooring boards

Some of the fixed windows are triple glazed. We used a Rationel Window for one of the windows (which is excellent), bespoke design triple glazing and in 2008/09 redid the sash windows with double glazed sashes with seals (which are pretty good) from Camden Boxframe 

We didn’t add any ventilation systems.


We took out the boiler and replaced it with an Air Source Heat Pump. We kept the existing radiator pipe runs, and in the rooms where we added insulation, we didn’t need to replace the radiators. In the areas that already had insulation we needed to upgrade to slightly larger radiators as heat pumps operate at a lower temperature than gas boiler systems. We also replaced the gas hob with an electric one and removed the gas from the building entirely. 

Generating Energy

We put 7 solar panels on the roof, and as well as generating the electricity we use, it also heats the water when there is excess electricity. We don’t currently export the residual electricity, because Good Energy (our electricity provider) has not got an export tariff in place. 

This was designed by Prewett Bizley Architects, Borisa Ristic & co (Builders) and Elite Renewables (Air source heat pump and Solar Panels)

We did an extension in 2008-2009 when we put in new double glazed windows, rebuilt an extension (with insulation) and redid the living room floor (with insulation). Between September 2020 and April 2021 we did most of the works described here, and moved out for about 5 or 6 months. 

Cost and benefits.

The works we did in 2020/2021 that related to the energy efficiency cost about £59k (excluding RHI grant). This is saving approx 5 tonnes of carbon dioxide per year. 

We got a Renewable Heat Incentive (RHI) grant for about £7k over 5 years.The energy efficiency measures were also rated at 5% VAT, rather than the usual 20% for other works.

We are now very cosy and warm, and uniformly so throughout the house. 

We’ve gone from using about 23,400 kWh of gas per year (around £2,500 per year), to 1,848 kWh of electricity (about £960 per year bought from renewable generators – eg Good energy at 52p per kWh), saving £1600 per year. 

The payback, including the Good Energy electricity, is approximately 30 years. 

Thomas in Grafton.

1. An air source heat pump (Mitsubishi Ecodan) and the associated hot water cylinder 

2. A mechanical ventilation system with heat recovery (Zehnder Comfoair 350)

3. Triple-glazed windows (Norrsken)

Jeremy in Alma St

For a cost of around £3K, we insulated half the house’s butterfly roof as follows:
For the rafters 75mm Kingspan Kooltherm was inserted between the rafters, and overlaid with 25-30mm Kooltherm with a plasterboard finish.
For the joists, we put in 75mm mineral wool between them and boarded this over.
The windows for that half of the house were double glazed at a cost of around £3k.
The temperature for that half of the house never goes below 16 degrees and is usually a solid 20 degrees in winter. In summer it is hotter, but that’s a small price to pay!

For the other half of the house the roof is insulated with 250mm Celotex CW3000 or similar between the rafters. The rooflights are double glazed.
Some of the walls in this half of the house have 200mm of insulation.

James in Alma St

10 Solar panels fitted in April 2022. Q peak Duo BLK ML-G9   Applied via the Camden Council scheme launched in 2022 to buy a large number of solar panels to lower the price. Wanted to get panels and a battery.   We had the panels installed but the battery has not yet been sourced. Only paid for the panels.  Paid £4543 for 10 panels and fitting.  Benefits – not done a proper calculation of the savings but guess we have cut electric bills by approximately 70%