Eco features: Solar Thermal + Solar PV + Well insulated
Andrew and Fiona live in a 4 bedroomed house in Pevensey.
Approximately ten years ago they had 16 solar PV panels installed to generate electricity. The solar PV panels provide enough electricity to run an electric car, an electric bike and an electric cooker as well as other household items.
Three years ago they had two solar thermal panels installed on their roof to heat their hot water.
The Kit: Two 2m2 Wagner flat plate solar collectors, with pump to transfer the heat to the hot water cylinder, plus expansion chambers. The collectors have a dark anodized coating on an aluminium frame which gives them the appearance of skylights.
The total cost:£3735 (includes all fixtures and fitting)
This cost excludes the hot water cylinder which was needed to store water collected.
Outcomes: The solar thermal system supplies all their hot water needs throughout the summer, and partially heats water during the winter. The estimated energy supplied by this system annually is 1654 kWh
Grants: Solar thermal systems are eligible for repayments under the Renewable Heating Incentive Scheme. This works out at £331.80 a year for seven years, or a total of £2322.55. This goes a long way to offset the original outlay and is in addition to the savings they make through reduced energy bills. The RHI scheme is open for new applications until March 2022.
Andrew talks about his experience with their solar thermal system in the video below.
The hot water storage cylinder with expansion chambers and pipework.
Solar PV panels
They have 16 solar PV panels: Eight on the front roof and eight on a South West facing roof.
The solar panels have a capacity to provide a maximum of 3.7KWh of electricity at any one time, (the amount generated depends upon the amount of sunlight, the angle of sunlight, time of day and year.)
The predicted total amount of energy generated during the year was 3,000 kWh per year. The actual output has been 32,000 kWh over 10 years, so better than predicted.
They bought their solar panels ten years ago when feed-in tariffs were at their peak. Under their FIT (feed in tariff) contract they get paid 55p per KWh generated and an extra 4p per kWh that is deemed surplus to their needs and gets automatically exported to the grid.
The house has cavity wall insulation and over the years Andrew and Fiona have been improving the insulation adding Celotex panels and rock wool into roof spaces and other voids. All their windows are now double-glazed and they have thick curtains to draw across their doors and windows on cold nights.
Suggestions on this page range from free and quick tips to whole house retrofit projects.
When a new house or extension is built, it must have a certain level of insulation. This will be added under the floor, within the two layers of the wall and in the roof. The external doors and windows will also have to reach a certain level of energy efficiency. The level of insulation recommended to make your home more energy efficient has increased over the years so your house may have insulation which could be improved.
Insulation will prevent heat escaping quickly making your home cosier, draught free and use less energy which will also reduce your bills.
Many of the measures needed to insulate your home can be quite costly. The government and local councils often provide grants and initiatives to help. Grants will hopefully become more readily available in the near future as we need to meet our Net-zero carbon target.
LEAP offers support for lower income households telephone for further information and support: 0800 060 7567 firstname.lastname@example.org https://applyforleap.org.uk
ECO – Energy Company Obligation
ECO is a government scheme to help reduce carbon emissions and tackle fuel poverty. Under this scheme customers with low incomes can apply to their energy supplier for help with energy efficiency measures, such as loft or wall insulation, or even boiler replacement. The aim is to reduce the cost of heating their homes. Medium and large energy companies (with over 150,000 customers) are obliged to provide a certain number of efficiency improvements according to their market share.
It’s a first come first served scheme, as once the energy companies have fulfilled their obligation within the current scheme, they may stop taking applications. The current Eco scheme (ECO 3) runs until 31st March 2022. The good news is that ECO 4 will run for four years from April 2022 with a planned expenditure of £1 billion per year.
6.5 million homes are eligible for help under ECO – You can find out whether you are eligible here . If you are eligible, you should contact your energy supplier for further information on services they provide.
It doesn’t have to cost the earth to reduce the amount of energy we use to heat our homes. Some things we can all try:
Close doors to empty rooms.
Put thermostats on radiators. Turn radiators off to rooms you are not using.
Make your own radiator reflectors. Cut a piece of cardboard to fit down the back of a radiator. Cover with tin foil and slip back down behind the radiator to reflect heat back into the room.
Close curtains before it gets dark to conserve heat. Tuck behind any radiators.
Fix lining to curtains to make them thicker. You can often find bedding or curtains in a charity shop which will work well as curtain lining.
Net curtains help to keep a room a little warmer.
Fit a long, heavy curtain over the front and back door. Cheap offcuts of material or long curtains can often be found in charity shops or online in places such as eBay or locally on Facebook marketplace, Freegle or the Friday-Ad.
Make draft excluders for doors.
Add another layer of clothing.
Exercise warms you up, is good for circulation and keeps you fit!
Keep a throw in the room for snuggling on the sofa.
Use a hot water bottle.
Add draught proofing to windows and doors. Simple Energy Advice: Draught proofing your home video Did you know: 40% of heat is lost through doors, windows and floors.
Replacing blown double glazed panels of glass. This is a lot cheaper than buying new windows. Contact your local glazing company. Window fitters can service your windows replacing any parts if necessary. Prolong the life of your windows by keeping them clean. Keep the mechanisms clean and oiled.
Choose a good underlay – this will prolong the life of your carpet. natural materials are more insulating and can be recycled more easily.
Adding insulation to solid floors. It is possible to break up a solid floor to add insulation and concrete over but the energy and resources needed may not be recovered in the energy savings. The room will feel warmer so this will need consideration. Insulation can be added on top of the concrete. This will add height so skirting boards and doors will need altering. Adding foil insulation under carpets will bounce some heat back into the room. More information on insulating a concrete floor here.
Whether you are planning to do your own insulation, or pay someone else to do it for you, understanding the different options available and how they are used most effectively can prevent you from making costly mistakes.
Learn: Free Retrofit training course from the Low Carbon Trust – this excellent course from Mischa Hewitt is free to enrol on and will teach you the science behind retrofit, why some materials are better than others, energy patterns in your home, how to identify areas in your home that need retrofitting and identify appropriate solutions.
If you have the budget for significant retrofit measures in your home, then you may wish to get some independent advice. Warmer Sussex provide impartial, expert advice to help you make your home more energy efficient. They also liaise with a network of vetted tradespeople who are able to carry out retrofitting. Their services include a whole house plan identifying priorities and the most cost effective measures; providing quotes from vetted contractors and project managing your retrofit and checking that all work meets quality standards.
In the second of our three sessions, we will explore steps we can take to:
reduce the amount of fossil fuel energy we use in our homes
reduce the number of new products and materials we buy for our homes
reduce how much we waste
and reduce how much we spend
See below for the resources referred to in the recording:
Program 11:00 – 12:00
11:00 The Eastbourne and Seaford story: suggestions, local schemes and activities for saving energy, resources and money – Andrew Durling, Gemma McFarlane and Jill Shacklock
11:30 Q & A with panellists: Steve Marshall, LED UK, Gemma McFarlane, Andrew Durling, Rachel Fryer
11:45 Online energy saving game. Make a team with your family or housemates.
If you’d like to ask our panel a question, we recommend you look at the relevant resources below first. You can ask your question at the live event, or you can send us your question in advance using the link below.
Eco features: Air source heat pump + Solar PV + Whole house insulation + Air tightness + MHVR + Compost Toilet
Rachel and Adam
Rachel and Adam live in a three bedroomed house in Newhaven with their seven year old daughter, Daisy.
When they bought their home two years ago they planned to extend it, at the same time as making it low carbon and as energy efficient as possible. Once they got started they found that some of the original walls needed rebuilding, so the first floor and roof were pulled down and rebuilt to high eco standards.
Insulation & (especially) airtightness need to be carefully designed for each individual house and have to be balanced against ventilation. Adam and Rachel installed MVHR systems alongside their insulation and air tight features. They recommend speaking to a specialist eco-architect for advice.
Rachel and Adam with one of their MVHR units (cover removed)
Two wood fibre insulating sheets (Steico Protect boards), one 6cm and one 8cm have been fixed to the external walls and rendered over with specialist lime render (Lime Green Prep-Bond WP render)
14cm wood fibre ‘wool’ insulation (Steico Flex) was built into the wall of the new dormers.
Air-tightness measures were designed into the structure of the house, including Intello Air-Tight membrane, Tescon Vana airtight tape and Blowerproof ‘liquid brush’ (an airtight paint).
A distributed mechanical ventilation and heat recovery (MVHR) system has been designed into the house, with two units set into external walls (one upstairs, one downstairs), and intelligent fans between different rooms.
The MVHR kit
They used the Free Air system by Blu Martin, distributed in the UK by Paul Home Heat.
The MVHR cost: Total purchase cost £6k (not including installation). When running at full pelt (which it very rarely has to) the MVHR system uses about 200W energy – i.e. about the same amount as 3 old-fashioned incandescent light bulbs.
Outcome: a reasonably airtight house that is warm & airy throughout the year.
Watch the video below to find out more:
The Solar Panels
The Kit: 7 photovoltaic panels (LG 320 Neon) giving 2.3 kWp. Includes Solis 2.5 Multi inverter, all meters and wiring and fitting
The total cost: £4.5K plus 5% VAT
Outcomes: On most days during summer months, they are a net producer of energy (ie their solar array produces slightly more energy than they use). Their solar installation is not that big, but all the other energy-saving measures mean that their overall energy consumption is low. Their annual energy use is 4600 kWh and the total energy generated via Solar PV is 2080 kWh. Once FIT and RHI payments are taken into account, their annual energy expenditure is approx. £85, but see below for more detailed information on their energy use and costs.
Solar panels just visible on the roof
The Air Source Heat Pump
The Kit: Mitsubishi Ecodan Ultra Quiet PUHZ-W85VHA2 air source heat pump plus Mitsubishi 210 litre hot water tank, under floor heating throughout the downstairs, 4 radiators upstairs.
The total cost: £11K plus VAT (includes all fixtures and fitting)
Outcomes: The heat pump serves underfloor heating, 4 radiators and their hot water requirements.
Rachel and Adam had their property disconnected from the gas main. This cost around £2k, and had to be done by engineers from SGN. Without doing this they would have been liable to keep paying a standing charge for gas, even though they had already had the gas supply cut off at the meter on their property.
The Kit: A Separett Villa 9000 urine separating toilet (£700) in the garage, and a Biolan Eco 220L composter (£820) in the garden.
“The toilet needs emptying once a week into the composter, which we find no more difficult or unpleasant than dealing with nappies – not a favourite job, but not a problem.
As well as getting great quality compost, it means we deal with all our toilet waste on-site. Our waste does not have to be piped away and purified using both mechanical & chemical processes, which add significantly to pollution & environmental degradation. Please read ‘The Humanure Handbook’ for more info.
By not flushing the toilet, we make significant savings on our metred water bills.”
As well as having the compost toilet system, Rachel and Adam try to use as little water as possible:
“We reuse bath/shower water, pre-soak washing up in old water etc. We also have a water-butt system for the garden which holds c 1000 litres rainwater. This has not run out at all since installation, including in the dry summer of 2021, so we have not needed any tap water to keep our veg beds happy.
All these measures save a considerable amount of water. Our metered water use comes to approx. 65 m3 per year, instead of the average for a 3 person household of 135 m3 per year. At current rates, we pay £320 per year for all our water costs, rather than the average of £580.
Our metered water use comes to about 65 m3 per annum.
Average water use for a detached UK house with 3 people is approx. 135 m3 per annum.”
Energy usage and costs
All their energy comes from electricity so there are no gas bills.
Total annual electricity use is 4600kWh = approx. £820 + £96 standing charge = £916
Total energy generated by solar PV is 2080 kWh which brings in approx. £80 generation tariff + £114 deemed export tariff. So the income from FIT (feed in tariff) payment = £194
So total annual energy payments = approx. £920 total annual receipts for FIT and RHI = approx. £835 which is a net annual expenditure of£85.
This energy use includes their house, heating, hot water and their electric car.
For reference, the average annual energy use for a family of 3 in a medium sized detached house is 12,500 kWh for gas and 3,100 kWh for electricity, with a total annual bill of £1163 (figures from Octopus Energy).
The table below shows their energy use across the year.
Energy use (KWh)
Energy generated (KWh)
Thanks to Adam for providing all this useful data.
Overall outcome: A warm, airy comfortable house that costs very little to heat, doesn’t use much water, and produces high quality compost for growing veg.
ADam and Rachel
Rachel’s Dos and Don’ts – Lessons learned from their whole house project
Thank you Rachel, for this very thorough and insightful list. It’s well worth a read if you are thinking of starting on a retrofit project.
Don’t do it ! Why put yourself through it!
Trust yourself: While the detail of designing and building houses is complicated, a lot of the broad ideas aren’t. Everyone is learning along the way and can and will make some mistakes
If you want to do an eco project make sure your architects really understand green issues – one thing we did get right! And try to make sure that their green priorities are the same as yours (no oil products / only local products as far as possible etc)
Try to find an architect and builder who have worked together. If you’re lucky enough to achieve this then get the builder’s input as soon as plans start to be drawn up so they can advise on costings before you have elaborate gold-plated plans
If you’re doing major renovation consider pulling the whole thing down – especially if it’s detached. Maybe not the greenest thing in some ways but it means you can do everything as you want from the beginning and you’ll save a fortune on VAT.
Consider how to project manage it. If you’re not a builder but know a builder you can trust, who you’re not using, who is willing to act as a consultant and do inspections every week or two, this will be well worth the money. This is probably the best thing as they’ll understand the practical challenges better than an architect but also be on your side and not want you to be ripped off
If you can project manage it, consider hiring specialists for jobs which need specialist skills such as plumbing, electrics, carpentry. The downside is everyone will blame everyone else for why it’s hard for them to do their jobs in the way they would like but we found working directly with specialists was much easier than depending on general builders and their subcontractors. It may take longer but save money.
Use specialist installers for marmoleum and MVHR
Think twice before installing marmoleum – it’s hard to find experienced installers and extra hassle putting it over under-floor heating
If you have bought a property and are paying rent elsewhere is it worth moving in while you wait to get planning permission and find builders you’re happy with? This can take the financial pressure off getting everything done as quickly as possible. It may be cheaper to do this and move out for 6 months later and get your stuff put into storage
Liaise with an airtightness specialist early on, get them to build things into the plans with your architect and check your builders are happy to consult with them in problem areas such as making holes in the house! Airtightness is as important as insulation but seems to be less well understood.
Make sure you withhold payment or part-payment until jobs are complete – you want to incentivise people coming to finish off the job
If possible seek advice on maximising solar potential before design and structural calculations are done
Check where the solar inverter and heat pumps are going to go before / during the design stage (not after the house has been built as we did!) – Well we did this but it still didn’t work out as planned!
Specify Suppliers and precise products – if we did it again we’d use the Green Building Store for all external doors and windows– it’s much cheaper but has a long lead-in time so you need to order early. It’s better to over-specify then you can negotiate with the builders if they have a reason to want to change anything
Specify U and G values for windows / doors – and pay to get an estimate of airtightness so you can hold the builders to that
If you want to have a compost toilet inside an airtight house it’s possible but you need advice from a specialist on how to do this
Consider how much you want to be dependent on Wi-Fi for appliances like thermostats and burglar / fire alarms, and weigh that up against having more cables coming in and out of your house which can impact airtightness
Read up on principles of green building. Even if you don’t understand the detail or the application, understanding the concepts will be invaluable.
Ask your builders to work to full-size hard copy plans and have them on display at the site. Some contractor’s staff tended to look at plans on their phones and we suspect that’s the reason they missed some important details.
Visit the site often. Don’t be pushy but don’t be shy of talking to the builders in details.
“Money spent getting a job done well is never wasted – the costs of repairing poor work can be high. It’s probably worth getting a PHPP calculation done (this tells you how close to PassivHaus you can get, taking into account airtightness and insulation etc) at the design stage, even if you’re not aiming to build to PassivHaus / Enerphit standard. That will give you leverage if the builders fail to build to a high enough green standard.”
What we got right
Architects whose design we mostly trusted and who understood what we wanted
Happy with most of the materials they recommended – steico wood fibre insulation, lime render
Happy with Earthborn paints
But despite that fairly short list, we’ve got a very energy efficient, warm house. Even if it could have been more energy efficient, more airtight, with more solar, it’s still pretty damn good. Now we’ve been here for a year and we’re settling into the house and how it works. In the middle of November, we haven’t had to turn on the under-floor heating. Our energy use is around 1/3 of the UK average for a house of this size (and that includes charging our electric car) and we’re generating a good proportion of our own electricity. Our water use is tiny and we have a great source of compost for the garden 😉
The house project has been fascinating at times, utterly hellish at times, and all-consuming for nearly two years. But we’ve now got a wonderful home which is truly our own.