September General Meeting
Many people are interested in saving energy and making their homes more sustainable, but often don’t know where to find impartial information. so September’s general meeting was dedicated to answering your questions about retrofitting and sustainable home improvements.
Panel
The question time panel of four included:
Nick Parsons (javascript:secureDecryptAndNavigate(‘gBoS9HMqSJrkw5AHGmLCUER7ml2Ku3gSIklF3HH56rG6hTWZyiu3i7ZUC+XME6zGGZYys+PBjUG1VHlXZm/+qpSzYY+fP6V/reHKG2L7BFGkwQuYXB8xp1zBIkh7hA==’, ’21f541da875de9f11ef7b5b7060361c959f5f144b2a02b56b51860876e5bb063′)) an experienced retrofitter and sustainable building consultant https://carbon.coop/ http://syec.co.uk/sustainable/
Prof Michael Corcoran (javascript:secureDecryptAndNavigate(‘diEkyuBvuFysWNRV8dH0nxUQLhZ6UNid7qzsWdcuQ5ZSDPVw6r0b2E3bNo90T/+jFSDu9W7JQpGSG11gSY1OjzKdx9yRsGpGUlRt7AiPW8Y=’, ’21f541da875de9f11ef7b5b7060361c959f5f144b2a02b56b51860876e5bb063′)) a building services design engineer and advisor on buildings and the environment https://uk.linkedin.com/in/prof-michael-corcoran-86411225
John Cotton (javascript:secureDecryptAndNavigate(‘w9cAqGix3ud3ThtJbBoKVud5TyQq7UlR6gdMTqHMq/7zaXQSbaIQMm2kyT1um7NC6/FdzALJrFDIZi0BO1cxC7ifaIHTeNLYpvsKFw==’, ’21f541da875de9f11ef7b5b7060361c959f5f144b2a02b56b51860876e5bb063′)) an electronics engineer who has installed various energy systems in his 1975 detached stone-built cavity wall home in Bamford https://hopevalleyclimateaction.org.uk/eco_homes/8-ashopton-drive/
Jon Whitley (javascript:secureDecryptAndNavigate(‘Xu3JZtvLwiSEwe6RhDzApAaFoFGP0eEikquOOmnXgAMtQCBXecuDU4v1zz8a+SJQVFyQs0EWMFpZdxArXFmlADWWOnaTMOTfyImeu60=’, ’21f541da875de9f11ef7b5b7060361c959f5f144b2a02b56b51860876e5bb063′)) who has insulated and fitted a heat pump in his typical stone built cottage in Edale. https://hopevalleyclimateaction.org.uk/eco_homes/middle-ollerbrook-cottage/
Quick tips to save energy this winter
What are the best options to maximise energy efficiency this winter with minimal spend and upheaval? In other words, what’s the best way to save money heating your home this winter without paying more than you would need to pay on your bills anyway?
- Cling film secondary glazing. Tape the windows first with masking tape to reduce drafts.
- Install radiator valves to help zone the house and switch off or reduce heat in under-used rooms and bedrooms.
- Turn down the boiler temperature now and increase it incrementally as it gets colder this winter.
- Draught proof your doors and windows.
- Good-fitting heavy curtains, as long as they are not over a radiator.
- Get your plumber or gas engineer to check that your boiler is condensing.
- Adjust your shower heads, if you can, to deliver less water.
- Insulate pipework from boiler to hot water cylinder and add insulation to the cylinder.
- Put radiator foil behind radiators to reflect the heat back into the room
- Use masking tape to seal draughts, especially at floor level.
Problems and lessons
What problems did you experience doing your own retrofit and what would you do differently?
Jon Whitley It’s a learning process, but happy with what I’ve done so far.
John Cotton Had to pull the house apart to install under floor heating and found lots of defects in the way the house had been built that needed rectifying. Now get condensation in the window reveals caused by thermal bridging that needs addressing. Would have added additional insulation and would have paid more attention to air tightness. Would have insulated internally to a higher standard. Loft has only 100mm under boards but ceiling temperatures and therefore losses are lower with underfloor heating.
Nick Parsons Made loads of mistakes. I used blobs to stick insulated plasterboard to internal walls, rather than a perimeter bead and cross hatching. This caused air movement behind the insulation, negating its benefit.
Michael Corcoran The approach advocated by PAS 2035 suggests assessing the whole house systemically and devising a comprehensive plan. In practice many homeowners do things incrementally as and when they can afford it or are able to put up with the disruption. Nevertheless, it is useful to have a plan for the whole that you are working to. But, if some rooms are insulated and some are cold and uninsulated you need to be careful with behaviour to not create moisture in air-tight rooms that can condense on cold surfaces.
Storing surplus electricity from solar panels
What’s the best battery to look for when fitting 4-5kW of solar panels? What should I be looking for in terms of spec?
5kW panels would produce 37 kW hours per day on a bright summer’s day. (There is a 5:1 ratio of electricity generation between July and January.) You would only use a fraction of that in summer. A 4-5 kW array would produce about 3400 kW hours/year and a typical family would only use 1000 kWh of this, which would leave 2400 kWh available for storage or export.
A good way of storing this energy would be in an electric car battery if you could have the car at home during the day. Alternatively, the next best thing would be to use the electricity to heat water using a diverter that optimises surplus solar energy. A 130 litre tank could use up to 8 kWh per day. Then you could export the surplus to the national grid. With Octopus the export tariff is 7p / kWh.
We also need behavioural change, for example to run dishwashers and clothes washing machines when the sun is out.
All these alternative ways of dealing with the surplus electricity are much cheaper than a home battery which under current conditions would take decades to pay-back. A home battery/s would have to be large enough to power a home during an evening and night in winter for a few dull days. The Tesla PowerWall 2 at 13.5 kWh would be large enough but costs around £10k fitted. We need a step-change in technology to manage electricity storage better.
Fitting solar panels
My roof needs replacing, what are the pros and cons of over the roof and inset panels?
Panels mounted above an existing roof covering run cooler and are therefore a few percent more efficient than inset panels. They are also cheaper. But if replacing an existing roof covering, inset panels save some of the cost of the new roof covering.
If one needs a new roof and wants solar panels, should one contract a roofer or a solar panel provider?
Best to approach an MCS registered solar panel installer first. They will be able to recommend a suitable roofer that they have worked with before. Only MCS registered installations are eligible for the smart export guarantee payments.
Replacing a gas fired boiler
I have a combi boiler and have been advised by a surveyor that to get best use of the solar panels I would need a new system boiler and a hot water tank.
There is no need to replace a functioning combi boiler to accommodate solar panels. You could fit a diverter valve and hot water tank and run the combi boiler as a system boiler.
Finding someone to do the work
Is there a list of local consultants to talk through options and/or manage projects to optimise renovation work?
The Government’s Trustmark website has a database of accredited assessors and contractors you can search by post code. In practice, they are few and far between in our area and many competent tradespeople have failed to register. . We need a much larger national program of training and a simpler cheaper system of accreditation.
One Response
how do you store energy from solar in the car battery?