Go Zero

From The Times, Oct 2006, answering readers questions onenergy efficiency and renewable energy.

Tempted by a wind turbine?

I can't start putting solar panels on my roof, but I want to be a bit more environmentally friendly. Are there ecologically minded energy companies out there? And if so, will I have to pay more than I currently do if I switch to them? J. G., Southampton

Karen Darby: There are a number of ecologically minded tariffs available from different energy companies. The question you should ask is "how green do I want to be?". Companies such as npower offer their tariff (Juice) at the same price as their standard product. 'Juice' works by matching your annual electricity consumption with energy generated from a renewable source, so you are replacing the energy you have used from non-renewable (brown) sources with energy from renewable (green) sources. However, npower, like other companies such Powergen and British Gas is not a renewable energy company as most of the energy they produce comes from coal, oil & gas. If you're really committed to moving to a renewable supplier, Ecotricity, Good Energy & Green Energy are available. They do cost more than the other tariffs already mentioned, but they only generate their energy from renewable sources.

Perplexed by planning permission

How much would solar panels cost (including fitting) for a 3 bed semi detached property and what exactly will it power? With regard to wind turbines, I understand B&Q are supplying these and that we will no longer need planning permission. Can neighbours still raise objections and how much energy will this provide for my property - we have 2 adults and 2 children? Sharon Tregaskes, Chelmsford

David Hood: There are two types of solar system you can install into a domestic property. Solar thermal collectors produce hot water and can supply about 50-60 per cent of your annual domestic hot water requirements. A system for your house will cost in the region of £3000-4500 including a new hot water cylinder and installation.

A Solar PhotoVoltaic system produces electricity and, depending on your location, can produce between 700 and 850kWh a year for each kW of PV array. A 1kW installation will cost about £6000, then about £10-11,000 for 2kW, etc. The average house uses 3000-4000 kWh/year, but this can easily be reduced by half by use of basic energy efficiency measures (low energy lightbulbs, not leaving things on standby) and having 'A' rated appliances.

As for roof-top wind turbines, you will still need to speak to your planning authority to se if it requires permission to erect a turbine at your location. There is very little independent testing of the roof mounted turbines at this time.

Energy efficiency is still the key factor, and should be looked into in depth before considering any renewable energy systems. Contact the Energy Savings Trust for advice.

We are keen to get photovoltaic and hot-water solar panels, do we need to get planning permission? Alison Moore, Dorset

Keith Marsh: Solar PV (photovoltaic) uses energy from the sun to create electricity to run appliances and lighting. PV requires only daylight - not direct sunlight - to generate electricity. Solar water heating systems use heat from the sun to work alongside your conventional water heater. The technology is well developed with a large choice of equipment to suit many applications.

With both technologies, some local authorities require planning permission to allow you to have them fitted, especially in conservation areas or on listed buildings. Always check with your local authority about planning issues before you have a system installed. Obtaining retrospective planning permission can be difficult and costly.

Have a look at the Low Carbon Buildings programme website (www.lowcarbonbuildings.org.uk) to find out about grants available to install both of these technologies.

Shy solar power providers

It seems the market should be saturated with providers of turbines, solar panels, insulation units, water storage devices, but no. I must be looking in the wrong place. I would invest in and use most of these things, but as with so many people I am time short to go and seek. What's the solution and where are all these people hiding? W. H., London


David Hood: The irony is that all of the systems you mentioned are (or should be) easily available, and there is an ever-increasing group of suppliers and installers across the country. If you are having trouble finding people in your area, I would start with The Energy Savings Trust, and the grant programme they are administering, the Low Carbon Buildings Programme. There is a list of accredited installers with this grant programme, so this is a very helpful resource. You could also try the relevant Trade associations, such as the Solar Trade Association for Solar Thermal systems, The British PV association for PV, etc. If you still are having problems, the Centre for Alternative Technology offers a free information service that can direct you towards all of these and more.

Keith Marsh: The Low Carbon Buildings Programme website (www.lowcarbonbuildings.org.uk) has a list of accredited products as well as a list of accredited installers for all types of renewable energy technology from solar panels to mini wind turbines. For information on Energy Saving Recommended lighting, appliances, insulation and hot water systems go to http://www.energysavingtrust.org.uk/recommended

Green grants

My daughter has just purchased her new home and there is no insulation in the loft. Is she eligible for a grant to fund the insulation and if so who does she contact? John Hudson, Sheffield

Keith Marsh: Insulating your loft is one of the simplest ways to save energy and you can even install it yourself. By insulating your loft to the recommended depth of 270mm, within a year you could save between £180 and £220 off your energy bills. Your daughter may well be eligible for a grant or offer to help towards the cost and an easy way to find out is to search the Energy Saving Trust’s grants information database www.energysavingtrust.org.uk or alternatively your daughter could speak to her local Energy Efficiency Advice Centre on 0800 512012.and a local advisor can advise her on the next steps to take.

I would like to install solar panels on my two bedroomed cottage, are there any government or otherwise sponsored subsidies to do this? Jackie Coleman, Longridge

Keith Marsh: You may be eligible for a grant. UK wide - the DTI's low carbon buildings programme provides grants for householders. The Energy Saving Trust manages this programme and grants are available for microgeneration technologies including: solar photovoltaics, wind turbines, small scale hydro, solar hot water, heat pumps and bio-energy. Please see www.lowcarbonbuildings.org.uk for more information.

Countryside conundrum

We live in the countryside 12 miles north of Aberdeen in a traditional stone built cottage that has been extended using brieze block cavity wall construction. Roof is slate, windows double glazed. Floors in old part are solid concrete and new part are raised. At present our heating is by off-peak storage heaters so there is no wet heating circulation system installed.

We are trying to decide what the best solution for a green heating system would be. Would a roof mounted wind turbine be any use when most of our heating is off-peak? I do not feel photo-voltaic is sensible since that is most efficient for water heating and the winter nights are very long up here. We do have a field of 1 acre in addition to large garden but don't know anything about ground heat pump. Erica Hollis, Aberdeen

David Hood:. If you choose to stick with the electric heating system, the quickest and easiest way to green your heating is to switch to a Green Electricity Tariff. You are now able to buy electricity from anyone you choose, and there are now a variety of suppliers who offer electricity either partly or wholly from renewable sources. Typically they will offer two types of tariff: one at a similar price to what you pay at the moment, but a large proportion of the electricity comes from green sources, or; an entirely green supply at a small premium. The extra you pay (depending on your usage) might only the price of a few beers a year, which is a small sum to not be responsible for any CO2 emissions from your electricity.

Both Solar photovoltaic panels and a wind turbine would be linked into the grid connection in your house, so they would either contribute to the electricity you are using at the time, or be sold into the grid for you to buy back later. In that way, either could contribute to reducing your electricity bills, therefore your heating bills. Even in Scotland, solar PV will contribute electricity. At their optimum position (south facing, 30-45 degree tilt and no shading) you could expect roughly 700kWh of electricity per year for each 1kW of PV panels. Much has been made of roof mounted wind turbines recently, but many of their claims have yet to be verified. What can be said is that the output of a wind turbine is linked to the average wind speed in your area, and it is a cube-law relationship, so if you double the average wind speed, you get eight times the power out. If you halve it, you get an eighth! I would look a 5m/s being the minimum average wind speed before you would consider a wind turbine as viable. If possible, a free standing wind turbine will give better results and a more predicable output, as well as potentially less noisy inside the house. If there are trees, obstructions or other buildings about, I would think very carefully as to whether a wind turbine is right for you, as all of these will reduce the expected output.

A Ground Source Heat Pump requires you to have a wet heating system in the house. I would only really look at these as an option if you were willing to put underfloor heating throughout the property. If you do decide to install a wet system into the house, also consider the possibility of a wood-fuelled system. This will depend on the availability of logs or wood pellets in your area, but can be a very efficient and cheap heating system to operate.

Roping in the river

We have a stream at the back of our house and would like advice on how to convert the house to hydro power. Christine McLeod, Edinburgh

David Hood: The important issues with getting electricity from a river or stream are the Head and the Flow of the stream. The Head is the difference in vertical height between where the generator will be and the point where you will take the water from. The Flow is how much water passes the generator point in a period of time (typically minutes or seconds). For a site to be viable, you would ideally have a high head and a high flow. It is possible to make the system work with a lower head or flow, but if both are low it will be very unlikely. As a rule of thumb, the potential power can be calculated as follows:

Theoretical power (P) = Flow rate (Q) x Head (H) x Gravity ((g) = 9.81 m/s2 ) x efficiency of system (estimated at 50%) When Q is in cubic metres per second, H in metres and g = 9.81 m/s2 ) then, P (kW) = 9.81 x Q x H x 0.5

If you have a figure of at least 1-2kW (preferably more) then it is worth looking further at the site. You will have to approach the Environment Agency for an abstraction licence (yes, even if you are putting it right back again), the planning department, and I would recommend bringing in a company that specialises in installing hydro systems at this point too.


Wind or sun?

I am am considering fitting a domestic wind turbine to generate electricity year round as a supplement to mains supply. I am aware that electricity can also be generated by solar roof panels, can they be combined? If so what, is the most efficient choice and what are the regulatory hurdles I have to clear? Finally, where would I find a competitive installer? Mike Smith, Staffordshire


David Hood: The first consideration has to be energy efficiency. This will reduce your bills and CO2 emissions and will make any system you install afterwards contribute a larger portion of your energy requirements. You can produce electricity through both solar PV and a wind turbine, and in both can be incorporated into your home and connected to the national grid. Which will produce the most electricity will depend on the location, as explained in the other answers above. You will need to speak to your planning department if you wish to install a wind turbine, but a solar PV array may fall under permitted development and therefore not need planning permission. The installer in your area should be able to advise as to the rules and restrictions in your area. For installers, I would check the accredited installers list on the clear skies website, which is the current list for the Low Carbon Buildings grant programme. You could also check the Solar PV Trade association.


Helping your heaters

My 2 year-old house has an energy efficiency rating of 86. I thought this was out of 100 and it looked good. Until I found it was out of 120 - not so good. What measures can I take to improve the energy efficiecy of the house. Unfortunately I do not have a condensing boiler. The house seems to have good roof insulation and is double glazed throughout - but the radiators are all on outside walls which is not efficient. Judy Phillips, Warminster

Karen Darby: You can be energy efficient by taking really simple steps such as turning off lights when they are not needed, keeping curtains closed at night to help keep the heat in and not leaving TVs and computers on stand-by. You can also install energy efficiency products such as reflective radiator panels and energy efficiency lightbulbs. These will help cut energy use dramatically. Energy saving lightbulbs only produce light and not heat, so they use up to 80 per cent less energy than ordinary light bulbs. It is also worth installing heatkeeper radiator panels. As the radiator warms up, 70 per cent of the heat produced is simply heating the wall behind with only about 30 per cent used to heat the room itself. By fitting the panels in your home, you will find that your radiators start spreading the heat evenly and eliminate cold spots. They will also help the radiators to warm your rooms up twice as quickly as before.