How to Specify Your Eco Home

The Concept

There is a huge range of differing green technologies available but with so much to choose from, deciding which combinations work best can be very tricky, and getting independent guidance is not always easy. In addition, some technologies are best suited to homeowners with different priorities. Our Eco Expert, Tim Pullen, is an energy consultant who owns Weatherworks (www.weatherworks.co.uk) specialists in assessing individual clients needs and recommending tailored solutions.We asked him to give his recommendations based on three of the most common cases.

The Young Couple

The Situation: Adrian and Jessica are money conscious, but want to up their homes eco credentials. They recently purchased a neglected Victorian terraced house in the town centre, which they are in the process of renovating with a view to possibly selling in the coming years.

Our Solution: Flirting with green features can be dangerous, as it can lead to eco bling stuff you bolt onto the house because it looks good but serves no useful function. In your town centre location, a wind turbine is out of the question wind turbines just dont work in urban locations but the roof is south facing so a solar panel may be a good idea. You are already dealing with insulation and double glazing and all I would add is insulation under the ground floor. You will probably need to take up the floorboards anyway and installing 200mm of mineral wool quilt will make a big difference to your heat demand.

In terms of space heating and hot water, you have two options. The first is to install a new gas boiler and you need to be sure that it is a high-efficiency, condensing, conventional boiler (not a combi boiler) which will allow the boiler to be linked to a hot-water storage tank and for the solar panels to pre-heat the water, reducing the load on the gas boiler. A properly designed solar system will produce all the hot water you need in the spring and summer, but will add about 3,500 to the budget.

Alternatively, you could install a wood pellet boiler. Prices range from around 3,000 for a largely manual machine to 10,000 for a fully automated system (Google wood pellet boilers and look out for Extraflame or Palazzetti at the lower end of the price range and Herz or Okofen at the higher end). The decision will be influenced by price, obviously, but also by space. The automated systems require quite a large area immediately outside the house to accommodate a fuel store. In this case, you would not need the solar panels as the boiler can produce all hot water and heating, and would be carbon neutral.

In terms of running costs, the normal gas tariff is maybe 3.5p per unit, and wood pellet is also around 3.5p to 4p per unit. The combination of solar panels and a high-efficiency gas boiler will increase your budget by around 3,500 and reduce your CO2 emissions to about 4.6 tonnes p.a. The wood pellet option could increase the budget by between 3,000 and 8,000 (over the gas boiler) but will reduce your carbon emissions to around two tonnes p.a.

The Retired Couple

The Situation: Peter and Cathy have massive energy bills and want to reduce those bills dramatically. Their property is a four bedroom detached house on the edge of a village and they are currently on oil. The property is well maintained with formal gardens and has not had a major upgrade in 20 years.

Our Solution: It seems that your huge energy bills are due to two factors: poor insulation and an antiquated oil-fired boiler.

Dealing with the boiler first, from your description I would guess that it is running at less than 50% efficiency. As a result, it is now effectively undersized for your home and consequently is running far longer than it should. The renewable alternatives in this case are wood pellet or a heat pump. Either of these would generate good running cost reductions but have to be discounted. A good, highly automated wood pellet boiler will cost 8,000 to 11,000 installed and while the manual labour involved in operating it is minimal, there is still work to be done. So it is discounted on the grounds of cost and convenience. The same applies to a heat pump. Installed cost will be 8,000 to 9,000 but installing pipes in the ground will mean destroying the 20 years of work you have put into your garden. A borehole is an option but will add probably 5,000 to the bill.

There is not much you can do about moving from oil without high capital cost, but the boiler is well past its sell-by date and replacing it with a high-efficiency condensing oil-fired boiler will increase the efficiency to 85%. It will cost less than 1,500 and reduce your oil bill by 30% on its own. In addition, insulate the pipes from the boiler to the hotwater cylinder, and the hot-water cylinder itself. That will give another, maybe, 5% saving.

While you have the men in for the new boiler, get them to install new control systems. As a minimum, fit thermostatic radiator valves to every radiator. These will allow you to heat to a minimum level rooms you dont commonly use and bring another big fuel saving at a cost of about 35 per radiator.

Next, insulate. In practical terms you can only insulate the roof and the walls, and both are a must. Cavity wall insulation will cost in the order of 400 to 500, and increasing the loft insulation to 300mm deep will cost a further 300 (both of these are installed costs). Taken together they will return their cost in fuel savings in less than two years, and save up to 2.5 tonnes of CO2 per year. One of the advantages of being of pensionable age is that you qualify for a grant of up to 50% on the cost of insulation.

A note of caution: some of the cavity wall insulation companies still use ozone-depleting gasses in the foam that forms the insulation. When choosing your insulation installer, make sure they are not using CFCs, HCFCs or any other greenhouse gas. If you can afford it, think about natural insulation for the loft. Sheeps wool or hemp are both great materials more expensive than mineral wool, but sustainable and a pleasure to work with.

Draught-proofing is also likely to have an impact. Around doors and windows is fairly obvious but also look at gaps along the skirting board and unused chimneys. Draughts can account for a 10% heat loss from the home and spending probably less than £50 on eliminating them is well worthwhile.

Next, double glazing. Replacement windows will be a huge capital cost probably £10,000 or more. A point to bear in mind is that although this price sounds relatively high, this investment will ultimately increase the value of your home, but you must decide if that is an investment you are willing and able to make.

Double glazing will reduce the heat loss through the windows by about one half. This may sound a lot, but in fact it will amount to a saving of about £100 per year. A payback of something over 100 years then.

An alternative is secondary double glazing. This could cost less than a tenth of the price of replacement windows, will cut out draughts around the window and improve thermal and noise insulation. Your local DIY shed will stock some proprietary systems, or look on the internet to find a secondary double glazing stockist in your area.

And, finally, the electricity bill. As appliances come to the end of their life, replace them with A+ rated. These use less electricity and less water. In the short term, change all the light bulbs to low energy. These will cut the electricity bill by £8 per bulb per year. There is a lot of talk about these low-energy bulbs giving poor light and a different quality of light, and in some cases that is true but there is a huge selection out there. Have a good look around and find the kind of lamps that suit you best and opt for the top-end specification rather than the cheap alternative.

The Self-builders

The Situation: Tom and Erica are building their dream home and want to protect themselves against future energy price rises. This high-spec property is to be built on a substantial plot on the edge of a small village.

Our Solution: Protecting yourselves against energy price rises means getting out of the oil economy. And that means generating all the heat and electricity you use. It can be done but you need to be thinking of a budget of at least £25,000.

From what we know of your location, a small wind turbine may be viable. You will need to check the wind speed in more detail a good DIY option is to buy a Wind Prospector from Wind & Sun Ltd for £300 + postage (www.windandsun.co.uk). This will give you the average wind speed and direction each day for as long as you leave it up and will provide all the critical base data for calculating the ultimate potential power in the wind.

Assuming that the wind speed is OK, a good turbine option will be the Skystream 3.7 from Segen. This is a 1.8kW turbine costing less that 8,000 installed, and with an average annual wind speed of six metres per second will produce about 70% of your annual electricity consumption.

While this is obviously not 100% of your likely consumption, you will always need a grid connection to meet peak demands (and days when the wind doesnt blow) and only relying on the grid for 30% of your demand is providing a good deal of protection.

You will need planning consent for any turbine and the critical issue will be what your new neighbours think of it. The general rule is that if your neighbours object, you wont get planning consent but that is changing under new Government legislation.

Turning to heat, the site is a natural for a ground-source heat pump. Either the Kensa 8kW or the Worcester Bosch Greenstore will meet your heat load. The Kensa is 4,500 for a complete kit and the Greenstore 4,200. They will both increase your electricity consumption by around 2,500kWh per year, meaning that the wind turbine will only deliver about 50% of the demand.

You will also need a solar panel to generate domestic hot water. This will add 3,500 to the budget and will need supplementing in winter with immersion heaters.

An alternative that gives greater protection is a wood pellet boiler. The price of wood pellets plateaued in 2006 and has fallen a little in 2007. The price is more likely to continue falling as more suppliers come on stream and supplies become easier to obtain.

An automated wood pellet boiler will cost around 8,000 to 10,000 installed, including a fuel store, but a lower cost option would be to replace your proposed log-burning stove with a wood pellet-fuelled stove with back boiler. These have a much lower level of automation in that you manually fill the onboard hopper with wood pellets and empty the ash can every two or three days. There is a good range to choose from including Rika, Palazzetti and Extraflame, with prices ranging from 2,500 to 5,500 depending on size and style. You will also need to install a flue.

A wood pellet stove with back boiler will deliver all the heating and hot-water needs, does not need supplementary solar panels and is completely removed from the oil industry.

Further Reading:

• How to Give Your Home an Eco Makeover
• Saving Energy: A Look at Renewables
• Eco House Design