First Steps

Improving the energy efficiency of your home covers a wide variety of aspects and options. I will focus on your heating requirements at this stage. It is wise to start by explaining how one can measure the improvements made to your house. How can you tell your home is more energy efficient. A very handy way to view energy is one that I first came across from reading David Mackay's very informative book; "Sustainable Energy - Without the Hot Air". Mackay uses Kilo Watt Hours (kwh) as the main measurement to compare and contrast various methods of home improvements and how they impact your energy consumption. A kwh is the unit of energy you will find on your electricity bill and is therefore easy to convert to cost in pounds whether it has been produced, lost or consumed. For the UK domestic user it costs roughly 11p per kwh in 2009. Power is another important concept. Power is the rate at which something uses energy and will measured in kwh/per day, month or year. This is a fairly easy unit for people to understand. For example, a 40W light bulb (power) left on all day would consume one kwh/day of energy. 40W ≅ 1kwh/day (1 KW = 1000W = 24kwh/day). With regards to space heating, the amount of kwh/day used will naturally vary significantly depending on the size of the property and its structure. As a rough guide, the average UK detached home with no insulation requires roughly 53 kwh/day.

When assessing the heating and efficiency of your home it is wise to look at the “leakiness” of the building. How much heat escapes on a consistent basis. The leakiness of your home will have two main sources

Conduction – the loss of heat through walls, windows, loft, ceiling etc
Ventilation – the loss of heat through open windows, doors gaps

A typical British home will lose the majority of heat through conduction (roughly 70%). In other words, with improvements in insulation and/or windows, one could make large reduction in heat use. Clearly, a badly insulated, large home with single-glazed windows will result in a higher rate of conduction and greater heat loss. Without getting into very technical details, it is possible to measure accurately how many kwh/day are lost both through conduction and ventilation. This kwh/day can easily be expressed in terms of pounds wasted and CO2 emitted. Look at the chart below and see the effect that insulation can have on a home when expressed as kwh/day consumed.


DETACHED HOME SPACE HEATING REQUIRED
No insulation 53kwh/day
+ loft insulation 43kwh/day
+ cavity insulation 30kwh/day
+ double glazing 27kwh/day
Space heating estimates (Eden & Bending 1985)

Just by adding loft and cavity insulation, there is potential to reduce the heat loss by 25% and because of incidental heat gains from greater insulation, this 25% reduction will actually translate to roughly a 40% reduction in the consumption of energy for heat.
Simple and relatively inexpensive steps , such as insulation, can be taken to reduce the heat consumption of your home. Below is a list of just some of the possible steps:

• Update all old, electrical appliances in the home including washing machine, tumble dryer and boiler
• Placing individual thermostats on radiators in bedrooms and living rooms to allow for more accurate temperature adjustments to rooms, which may have different temperature needs and different frequencies of use.
• Consider lowering set temperature evening by 1 degree Celsius. It has been calculated that a 1 degree reduction in thermostat setting can have as much as a 10% decrease in energy consumption over a year.
• Employ a handyman to go through the house and fill in gaps and cracks in the building to prevent excess ventilation heat loss.

My main interest lies in renewable energy systems and the advantages and disadvantages of the various products available (ground source and air source heat pumps, solar thermal, photovoltaics, wood pellets and chip burners, heat recovery systems etc). But what I have learned over the past years is that without properly setting the groundworks for your exisiting home, with improved insulation (cavity wall, loft and windows), upgraded appliances and better temperature control, it is a big waste of money to make a large investment in a renewable energy system. Your first step should be to look at the cheaper and far easier ways of improvong your home heating requirements before getting involved in any form of renewable energy system. You will often find that the largest savings are made from the simplest improvements whereas the installation of a renewable energy system is as much about creating energy securtiy and reducing your CO2 emissions as it is about monetary savings....