You will already have a heating system in your home (80% of homes in Britain have central heating or storage radiators). Most of these systems have been designed to cope with the higher heating load of a badly draught-proofed and insulated house. Many of them have the capacity to heat the house on the coldest day of the year to 21 °C and it is arguable that this is necessary. Many heating systems work most efficiently when they are working at maximum load, which means that if the system is designed for the coldest day it will be working less efficiently on all the other days. This problem is being solved with the latest designs of boilers and their controls.
Since we are looking at the ecological upgrading of an existing system we need to review the situation with the assumption that you have draught-proofed and insulated your home to as high a standard as you can afford. The most ecological sources of energy have already been identified. The best system for your particular home will depend on the characteristics of the building and your lifestyle. The alternative systems to choose from are as follows:
o Full central heating
o Partial central heating
o Individual space heaters where required
o Reliance entirely on incidental sources of heat
There are various reasons why you may not require a full central heating system. Here are some of them:
o If your house is small, compact and well insulated
o If your house receives sufficient passive solar energy
o If your house has an Aga or equivalent range
o If your house has a large ceramic masonry heater
o If you intend to concentrate your activities in only one or two rooms
We shall start by looking at full central heating, and work back from there.
Full central heating
The vast majority of central heating systems use water as the medium to transport the heat from the central boiler to where it is required. There are many other types of central heating such as hot air systems, underfloor heating and steam systems. However I shall deal mainly with ‘wet systems’ as it is the system you are most likely to have.
A wet central heating system consists in most cases of the following parts:
o The boiler that burns the fuel and transfers the heat to water
o The pipework that transports the hot water usually with the help of a pump
o The radiators that transfer the heat from the water to its surroundings
o The controls to ensure that the right amount of heat is delivered to where required at the right time
If central heating is already installed, the first question to ask is whether or not it is the right size system. If you have improved the insulation as indicated then it is likely that the system will be oversized and the boiler size can be reduced when you next replace it. You may also want to reduce the size or number of the radiators if this will enable the more efficient use of any of your rooms.
If you don’t have central heating, you may well be considering whether it is right for you. You need to make a realistic assessment of the costs of your existing system. For example, you may have individual heaters using existing chimney flues which could be resulting in considerable heat loss. If you have a relatively large house and you need to keep the majority of it warm most of the time, it is probably sensible to go for a high-efficiency gas central heating system and for the smallest boiler size compatible with the insulation.
A partial central heating system
If however you have a medium-sized two-story well insulated house, it is certainly not essential to install full central heating in order to ensure an adequate distribution of heat. Evidence suggests that if the ground floor is kept warm through central heating, sufficient heat finds its way upstairs by natural air movement upwards, encouraged by the stack effect and conduction through the ground floor ceilings to provide an acceptable temperature in upstairs bedrooms.
Even if you have central heating, it is probably a good idea to place a heater with some radiant output in the main living room to allow a quick warm-up of the principal room. It is useful in autumn and spring to be able to warm one room without having the whole system running.
Individual space heaters and alternatives to central heating
There are many different types of unit space heaters. Some of the most efficient now are the gas wall heaters with balanced flues. There is also the possibility of an efficiently designed wood-burning stove, if you are willing to spend the time tending it to ensure that it burns correctly. Many people have been persuaded into heating their homes with electric storage heaters because of cheap rate tariffs-which bear very little relationship to the amount of C02 produced-and the cheaper initial cost of installation. However, heating your house wholly by electricity is not ecologically sound and should certainly be avoided. Electric heaters can be justified only if they are used sparingly as a top-up heater to be taken on occasion to anywhere in the house and used in a very localised way for a limited period of time. The most effective heaters for this purpose are the small fan heaters with built-in thermostatic control. However, think first of wearing more clothes!