In 2015 we bought an old bungalow (built in 1924) with  a major renovation that had been abandoned part way through. We wanted to make it an energy efficient home without breaking the bank and so we employed a project manager.

Cavity walls were one problem. Standard architectural advice for more exposed parts of Northern and Western Britain is that cavity wall insulation can cause major damp problems. Driving rain can soak exposed external walls, especially in older properties with narrower cavities, and insulation can transfer damp to the ends of floor joists. We knew of a nearby property where such internal damp had already happened – very difficult to remedy as it’s not easy to extract cavity wall insulation!

We decided to have thick insulation on the inside of all external walls – somewhat reducing the room size, but not materially. In the accessible loft, we had thick insulation on the sloping roof undersides.

We discovered downsides to this when we had the Energy Performance Certificate (EPC) assessment we needed for  grants from Ofgem.

The pellet boiler

We decided initially on a pellet boiler and applied to Ofgem to receive a grant – an ongoing payment to reduce the running costs. We failed, apparently due to the fact that we had not followed the EPC advice and installed cavity wall insulation! There didn’t seem to be a recognition that this would be a serious mistake. We appealed, and failed, which is a terse summary of a very frustrating, exasperating and stressful period in our lives. Several years later, our ASHP advisor told us we’d gone about it the wrong way. We still don’t know what that was.

So in 2016 we opted for a sophisticated biomass boiler which ran on quality wood pellets, not wanting to go down the carbon-heavy gas route. We’d previously had a positive experience of running a less sophisticated pellet boiler elsewhere, with (we assumed) pellets made from genuine wood waste. It was very much cheaper to run than an equivalent gas boiler system, purportedly with a much lower carbon footprint.

But we began to doubt the real origin of the wood for the pellets, and questioned their quality, which was affecting the boiler’s running efficiency of the boiler. Cleaning out the fire grate every few days because of clinker build-up became a headache. It was no longer a sustainable option to an ageing user. It had to go.

The ASHP project

An ASHP seemed the only green option. So we employed an advisor with experience of these systems and of gaining RHI grants. Our experience indicates it needs serious forward planning.

We thought we had already covered our home’s energy efficiency. On a cold winter’s day (it has to be done when really chilly), CAfS (Cumbria Action for Sustainability) assessed the energy efficiency and areas of heat loss by thermal imaging camera, and finding obvious points of heat loss etc. https://cafs.org.uk/cold-to-cosy-homes-cumbria/

Recommendations included replacing extractor fans with products that had automatically closing blades, replacing seals around opening windows, or failing that, some triple glazing. External walls in our new extension appeared to have cold corners, apparently a common problem when builders don’t stick to the finer details of building regulations. Corner cutting!

We failed to find a window specialist to replace our window seals. It is not a DIY job I was prepared to do, and sourcing the materials produced more problems. The short-term solution has been to place masking tape around all opening window frames. Not pretty, but it works!

We replaced the two externally venting extractor fans with ones that had closing louvres, but after a few days they failed to close properly. It appears that the spring is too weak (a design or product quality issue). The practical solution is to either flick the blades closed, or regularly clean each front to remove tiny particles.

ASHPs seem to be really sensitive to colder weather. A plot of power consumption against time would be rather like an inverted temperature graph. However you need really cold weather to test the system’s effectiveness and locate significant ingress of cold air. Unlike a conventional heating system, an ASHP works less efficiently as it gets colder outside. A ground source heat pump would be better, not being dependent on the ambient air temperature, but it’s more expensive and requires a small field rather than a garden.

How much does it cost?

1) on-going costs Your bills will of course depend on your power supply company and tariff. But so far, on a cold winter’s day, the highest daily consumption has been between 50 and 60 units per day. It would have been higher, but we sometimes used our small (and highly efficient) double-burn wood stove when it’s below freezing outside. That consumption pro-rata through the year could never be acceptable. On a mild winter’s day, it’s around only 25 units. We would use about 10 units on all other appliances anyway. I’ve predicted an annual consumption of 8500 units, which is partly based on generating a significant amount of solar power during the spring and summer period, to at least provide hot water, if not direct solar insolation.

2) up-front costs This is where it gets expensive – far more than a conventional gas boiler. It depends how big your house is, and the challenges, but ours cost £14,000. We did recoup some by selling our pellet boiler for £2000, and must have saved many £100s each year we had it, compared to a gas boiler.

3) government grants The Ofgem domestic RHI offsets ASHP running costs. This scheme is to be replaced, but I’m sure the challenges of getting that grant will be similar. This time our advisor did it on our behalf, being familiar with the process, and knowing the problems. Even so, it was difficult, and we had two initial rejections. One because we failed to dot the “I”s and cross the “T”s, and another because our failed application in 2016 already registered us on the system. But it was third time lucky. We will get around £1100 each year, paid quarterly.

My conclusions

1) New houses are unlikely to be as well insulated as they should be. Our renovation experience is our guide, but I have seen newspaper reports of newly-built houses having the same problems. Builders will cut corners if they can.

2) a large proportion of our elderly housing stock is likely to be a real headache. Perhaps the most drastic but effective solution might be to drop pre-formed houses around existing poorly-insulated dwellings! The trite advice about installing roof and cavity wall insulation, and replacing inefficient light bulbs, just doesn’t cover it now. With an ASHP installation, the small faults also stack up, and really matter.

3) The points made by the Insulate Britain campaign are certainly valid, and a cause for great concern. With the current energy price increases,and a national failure to drive improvements in the domestic housing stock, combined with a future route towards ASHP installations across the whole of our housing stock, financial disaster looms for many. This is a crisis that must be addressed immediately. We are lucky to be less financially constrained than most, having no mortgage, and reasonable pensions.

Caveat emptor – let the buyer beware, about covers it. It is a minefield out there in the real world of making houses energy efficient. There are so many ways where you can make a mistake, such that I doubt it’s possible to avoid all the pit falls. Good luck!

Advocates claim enough geothermal energy in abandoned coal mines to heat 180m homes. The weed-lined disused road beside Lanchester Wines’ ageing warehouse on a north-east England industrial estate could not be more low key. But beneath the roadway’s many manhole covers are shafts which descend 200m into what could be the UK’s most widespread unused energy source – minewater. Lanchester Wines’ facility in Gateshead has by far the UK’s biggest commercial minewater heating scheme. It supplies all the warehouse’s needs, keeping millions of bottles of wine temperate, and also heats a neighbouring distribution depot. Advocates of using minewater for heating regard it as having particularly significant potential after the UK set the ambitious goal earlier this year of net zero greenhouse gas emissions by 2050. A quarter of all UK homes and businesses, some 9m buildings, and most of its largest cities outside London sit on former coalfields. Coal mining, which employed 1.25m people at its peak, powered the British economy for well over a century but the last deep mine closed in 2015. One of its underground legacies is the warrens of galleries through which run an estimated 2bn cubic metres of water, heated by surrounding rocks to 12-16 degrees Celsius. At present, minewater is a problem. Often high in iron and pollutants and potentially a threat to drinking water and rivers, its management by the publicly funded Coal Authority cost £18m last year. Yet Lisa Pinney, the authority’s chief executive, said minewater “could be a real contribution to zero carbon”. Opportunities she cited included horticulture, new housing and leisure schemes. According to Coal Authority data, heating currently accounts for 45 per cent of the country’s energy use and 32 per cent of its emissions. Meeting the government’s net zero carbon emissions target will require slashing fossil fuel use. Three extraction shafts outside the warehouse raise 39 litres of minewater a second to the surface using an open loop water source heat pump system. The minewater travels by pipe around the plant room into a heat exchanger. Here, the minewater heat boils liquid ammonia, concentrating the ammonia’s heat at 50 degrees C. This heat is then used to warm water which circulates around the factory’s heating system. Meanwhile the minewater, above ground for only two minutes, is sent back underground to warm up again. Now the 60-year-old Gateshead warehouse has a 2.4MW system yielding 6KW of heat for each kilowatt of electricity used. Its installation has brought the company its first payment, of £117,000 payment, under the government’s renewable heat incentive scheme. The company’s other nearby warehouse, which has hit an even better minewater supply yielding 67 litres a second, will within weeks start operating its own heating scheme. Mr Black expects payback on the £3.5m investment, part of £8m spent on renewable energy to make the company carbon neutral, within seven years. In Bridgend, in south Wales, the local authority is working with scientists to develop a minewater heating network for a local community. And in Durham the county council has invited tenders for heating a leisure centre swimming pool using minewater. Mike Stephenson, the BGS’s chief scientist, said the Glasgow studies were focusing on “de-risking” minewater heat use and that the research should be sufficiently advanced to enable investment decisions in two years.  “The wonderful irony here is we used coal to carbonise the economy,” he said. “Now we are going to use the coal mines that exist to decarbonise.”

Financial Times »

Engineers in Stirling are getting ready to open the UK’s first low-carbon energy hub which uses waste water. Scottish Water aims to heat several public buildings, including a school, a leisure centre and a stadium, through a mixture of cutting-edge technologies, including heat pumps, at its sewage works at Forthside. Their £6 million scheme, which has financial backing from Stirling Council and the Scottish Government, was visited by First Minister Nicola Sturgeon yesterday ahead of its switch-on next month. The new energy hub consists of a conventional natural gas combined heat and power (CHP) engine, heat from a waste water heat pump system, thermal stores and back-up gas boilers for the district heating network. The CHP engine generates heat for the public buildings and electricity for the sewage plant and the waste water heat pumps. The heat from waste water technology, provided by SHARC Energy Systems, uses a heat recovery unit to separate liquid and solid waste, which is returned to the treatment process. A heat exchanger transfers the heat from the waste water to the clean water using a closed loop system. A heat pump increases the temperature of the water, which is then delivered to the district heat network. Electric heat pumps – essentially reverse fridges – are being developed on an industrial scale across the planet. In Clydebank, local authorities hope to use pumps to capitalise on the relative warmth of the local river to heat a new neighbourhood. Scotland has Europe’s worst record on renewable heat.

Herald »

Using hydrogen to heat homes and power vehicles will play a vital part in Britain’s efforts to meet stringent climate targets and can’t be dismissed as an expensive pipe dream. That’s the conclusion of National Grid Plc’s network service operator in its annual Future Energy Scenarios outlook. It anticipates 11 million homes will be heated by hydrogen by 2050, which is half of the number currently using natural gas. To get to a world that limits global warming to acceptable levels, hydrogen will be in widespread use across heat, transport and industrial processes, National Grid ESO said in the report. Policy makers should act immediately to maintain hope of hitting the government’s net-zero carbon emissions target by 2050, the network operator said, urging measures on a “significantly greater scale” than it had suggested a year ago.

Bloomberg »

DANISH-style district heating projects could cut fuel poverty in rural communities, according to a joint paper by gas firm Calor, think tank Common Weal and the Energy Poverty Research Initiative. The cost of rural district heating is not substantially higher than urban district heating schemes. This is because, while the distances are greater, the necessary pipework is easier to install because access is easier.However, this solution may only work for 60% of properties and those that cannot be connected could use biogas boilers in conjunction with building-mounted solar generators, the research found. The conclusion is based on research carried out with Glasgow Caledonian University and comes decades after Denmark took steps to create its large-scale networks, which collect “waste” heat from factories and transport systems and redistribute this. They also take in energy from conventional power stations and renewables. More than 90% of rural residents who are income poor are also fuel poor, according to research. This is far higher than in towns and cities and the problem is linked to poor physical and mental health and lower education attainment. Some campaigners summarise the situation for struggling households as a “heat or eat” choice.

The National  »

Really disruptive technologies tend to be fairly rare in the renewable energy market. However, the heat batteries developed by Sunamp, which specialises in this area, look to be capable of being more disruptive than most of the innovations one sees in this space. Andrew Bissell, the CEO of Sunamp, claims that his products are highly likely to make conventional hot water cylinders obsolete in a relatively short space of time. The technology is now in its third iteration and is barely a third of the size of a typical hot water cylinder, such as households use for hot water. However, the company is currently prototyping much larger versions capable of scaling up to provide the heating needs of commercial companies from palette-sized to container-scale. In 2013, the Department of Energy and Climate Change gave Sunamp a contract to put the thermal storage system, alongside off-peak electricity and air-source heat pumps, into seven homes as a proof of concept trial. That was very successful heating the homes at half the cost of natural gas. The Sunamp put heat batteries into 650 homes. These were in two housing associations, East Lothian Housing and Castle Rock Edinvar.

Herald  »

Research from Northern Gas Networks and ITM Power concludes large scale power-to-gas energy storage could integrate with current gas networks. Ambitious plans to harness hydrogen’s potential as a form of energy storage and then inject the resulting green gas into the existing gas network could be delivered at scale, according to a major new government-backed feasibility study. Northern Gas Networks (NGN) and hydrogen technology specialist ITM Power announced this week that they have completed a collaborative desktop study, funded by the Department for Business, Energy and Industrial Strategy to explore the potential for large scale power to gas installations. The Power-to-Gas study examined potential deployment of large-scale storage capacity of 50 MW and above within the boundaries of NGN’s distribution network. It concluded that after accounting for seasonal variations in gas demand and the amount of hydrogen that would be able to be produced and blended with natural gas, a large area of the existing NGN grid could support power-to-gas.

Business Green »