Book - School of Science and Technology

Chapter 23Running costsThe cost of operation of any system providing space heating, ventilation, air-conditioningor hot water supply will depend upon a number of variables including:. fossil fuel consumption. power consumption and maximum demand. water consumption. maintenance and consumables. labour. insurance and similar on-costs. interest on capital and depreciation.The amenity value of various fuels may enter into these considerations. In some cases, suchas an industrial application, convenience and cleanliness might be unimportant whereas in abank or office block they would merit first priority. Similarly, the character and anticipatedlife-span of the building may bear upon choice and a fuel which would be suitable for a wellequippedsolid structure would not match the expendibility of, say, a system-built school.When selecting systems for a building it is necessary that both the initial cost of theinstallation and the operating costs be calculated for all the options to establish the mostappropriate balance to suit the client's particular circumstances. In some cases initial costsmay be the principal factor, whereas for others low operating costs may be the priority; inmost cases, however, there will be an optimum choice somewhere between these twoextremes. In addition, there are other factors to be taken into account such as reliability,health and safety and environmental issues.Energy costs over the last few years have been relatively stable, and for some energysources have reduced, compared with the situation which existed following the `energycrisis' of 1973. Since fossil fuel is a finite resource, it is likely that energy prices will beginto rise again in real terms in the foreseeable future, but there is no way of predicting whenand by how much prices will rise. Figure 23.1 shows how energy prices have increasedsince 1972. It has been estimated that approximately 55% of national annual consumptionof primary energy in the British Isles is used in building services and that about 50%of this relates to the domestic sector. Economy measures over the past 25 years or so havesucceeded in reducing energy intensity, that is in terms of kWh/m 2 , but the growth inoutput has caused the overall consumption to increase.The UK government is now acknowledging that climate change (resulting in the mainfrom fossil fuel burning causing the greenhouse effect and in consequence global warming)has to be addressed and it has signed-up to international agreements (principallyKyoto, 1997) to reduce greenhouse gas emissions to 12.5% below 1990 levels within the