Effective Management of Energy Use
Fig 2. ZICER building at UEA
Energy use, even in old buildings, can be reduced with careful and effective management. For newer low energy buildings such management is even more important and many, new ultra low energy buildings at buildings at the University of East Anglia have seen their energy consumption for heating reduced by 50% or more through creative adaptive management. An example is the ZICER Building at UEA which won the low energy Building of the Year Award in 2005. It has an ultra low heating requirement having quadruple glazing and an effective regenerative heat exchanger for air circulation. It also has a large 34 kW photovoltaic array of solar panels on the roof and upper façade.
When first completed, heat energy data was recorded at regular intervals and plotted against external temperature. A trend line is to be expected as heating energy requirements rise as the external temperature falls.
The results are shown by the red dots and line in Fig. 3. After sufficient data had been collected to cover all temperatures, the results were examined and it was found that modifications to the controls – such as siting of thermostats, operation of time switches etc resulted in a reduction of 57% as shown by the green points and line. At the same time studies of thermal comfort were done both before and after the change in strategy and an additional benefit arose in that occupants of the building were more satisfied with their environment.
A second example shows the benefits from collecting heating consumption data in a church. The church in question is heated by three gas hot air heaters, and there is no other use of gas in the premises.
Weekly data showed over the summer showed that though there was no heating on there was still gas consumption amounting to approximately 175 kWh per week coasting over £9 a week (Fig. 4).
Investigation showed that the cause was the pilot lights which were on continually. This was proved when, for several weeks, the pilot lights were turned off. When the heating season started again, just one pilot lights was left on continuously, and the churchwardens would reignite the other two when they arrived before a service. Overall there was a monetary saving of £200 a year and a carbon saving of over ½ tonne of carbon dioxide as a result of such action nvestigation showed that the cause was the pilot lights which were on continually. This was proved when, for several weeks, the pilot lights were turned off. When the heating season started again, just one pilot lights was left on continuously, and the churchwardens would reignite the other two when they arrived before a service. Overall there was a monetary saving of £200 a year and a carbon saving of over ½ tonne of carbon dioxide as a result of such action
Figure 5 Electricity consumption in a large office building in Norwich.
Another example where effective management can reduce costs and carbon emissions in buildings if highlighted by the trends of electricity consumption in an office block in Norwich. In a scheme to reduce energy and carbon emissions, low energy lighting was installed progressively through the building over a period of several months. Monthly electricity consumption from 2003 to 2005 is shown in figure 5.
During 2003 and early 2004 before installation of the low energy lighting began, there was a fairly constant consumption of 31800 kWh/month which represents the baseline consumption. The improvements from low energy lighting are shown during the period July 2004 to February 2005, and thereafter there was a new baseline established which continued until May 2005 of 22800 kWh per month representing a saving in emissions of 55 tonnes CO2e, and a monerary saving of £5000 a year.
Subsequently, the consumption rose unexpectedly, and over the next 6 months, no less than an additional 57 tonnes were emitted costing an additional £11000. When questioned in early January 2006, those responsible said there was a fault in the heating and air-conditioning system such that both were on simultaneously and fighting against each other. They reported that it would cost over £1000 to fix, and were horrified to learn that they had wasted 10 times that amount in just 6 months. This demonstrates the importance of good record keeping and management.
In the case of transport, savings of up to 15% in emissions can be achieved at no extra cost by slow acceleration and minimising braking by taking the foot off the pedal early when approaching roundabouts and traffic lights. For those with a hybrid, plub-in hybrid or electric vehicle, further savings can be achieved using the regenerative brake on slowing in preference to the foot brake.