PhD Thesis - Energy Systems Research Unit - University of Strathclyde

of the system diminishes with increasing LPG prices. The plots however do show asimilar financial sensitivity to the building’s energy demand – the higher the usefulenergy demand the higher is the PW of a project. Measures aimed at reducing eitherthe thermal demand (e.g. by improving the building fabric) or the electrical demand(e.g. by improving the electrical efficiency of appliances), therefore have adetrimental effect on the financial value of a project. Similarly, low operating loadfactors such as that experienced by the plant connected to the 3 household building(Scenario 1) tend to create a situation where the PW is very small, bordering on thenegative with increasing LPG prices. In fact, at the current LPG price the systemconnected to the 3 household building is already almost at a break-even point.On an individual building basis, in the case of the 6 household building the highestdifference between the different scenarios is that due to the improvement of electricalefficiency of appliances. In the case of the 3 household building the highestdifference between scenarios is that due to the improvement of the building fabric.The reason for this difference is once more the magnitude of the individual CF termswhich reflect the changes in energetic performance due to the different scenarios.Finally, considering that, as shown in Figure 5.17 for Scenario 2 Low/Current efficiency ,only one term in the cash flow equation is dependent on the assumed LPG price, theresulting CF and PW plots are both subject to a constant linear decrease reflectingthe increasing fuel costs.218