Watt-Meter Readings
As a directly related effort, Building-E is being studied for sustainability. One of the studies involves assessing its energy footprint.
Currently a simple walk-through energy audit is being applied to Building E with the same to follow for other buildings.
A preliminary assessment of the main items of energy consumption is being studied. There are two watt-meters installed in the building. These basically give the energy consumed (in kWh) within the building by the Mechanical systems (basically the Cooling systems) and the remainder of the buildings appliances. Table 1 shows the weekly data provided by the watt-meter readings.
The available consumption data for June indicates that the cooling systems use 29% of the total electrical energy consumption of the building. The actual energy consumption for the building for June was found to be 16674 kWh.
With a footprint of about 1700 m2, the June building energy intensity is figured to be about 10 kWh/m2/month of June. This figure needs to be calculated for the remainder of the months of the year to obtain a full yearly energy consumption index – a BER index as classified in the figure. A very optimistic figure could be obtained by multiplying by 12 months: 120 kWh/M2/yr – this will have to be seen as typical commercial buildings have a reported average annual BER of 265 kWh/m2/yr [Hinge & MacDonald, 2004]. Once the annual figure is found, RHU’s building-E BER will be published.
Simulation and Modeling
The building simulation software eQUEST was used to approximate the buildings energy data. This not only allows benchmarking but gives indications of measure that may result in future savings. A baseline simulation was performed using the best available date. The results are shown and are presented in the figure below.
A comparison of actual consumption versus eQUEST generated results shows reasonable agreement – notably in the cooling systems consumption. For June, the software gives a consumption of 4780 kWh for the cooling system(s) which is very close to the 4835 kWh figure that was measured. There is still some need to synchronize the other energy consumptions which are 16675 kWh by direct measurement and 13600 kWh as given by the model for June.
In fact, the software allows projection of energy consumption for a whole year. The figure (pie chart) shows that the cooling system consumes 23% of the yearly energy expenditure. This translates into about 33 MWh of electrical energy per year out of a total of about 142 MWh.
eQUEST finds its greatest usage in assessing anticipated reductions in consumption as a result of an energy measure that may be taken. For existent buildings, measures include:
A graph comparing the energy consumption before and after a certain measure is now shown. Replacing the single pane windows by low-e double pane windows shows a small reduction in energy consumption per summer month. This is being investigated.
Photovoltaics for Building-E
Not only can energy conservation measures be applied to Building-E at RHU, but it is also possible to generate some autonomous electricity via solar Photovoltaics. With a total roof area of about 1700 m2 being virtually shade-free all day, the building is estimated to be able to generate about 100 kWh peak or possibly more depending on photovoltaic efficiency.
As for the building E annexes, there are plans to improve their aesthetics as well as their climatic conditions. Having largely transparent window walls and roofs, they are usually very hot in summer and very cold in winter. In addition to adding reflective coatings to the windows, there has been some study of what to do with the roofs. The most attractive options have been determined to be either green roofs or pitched slate roofs – Photovoltaics has not been deemed feasible. This is due to somewhat excessive shading for most of the annexes. Figure … shows a solar shading diagram (altitude vs. Azimuth diagram) for the two candidate locations (Worst and best) indicated on the picture of Building-E and its annexes. The shading diagram shows the worst location (in black) to be fully shaded until after 10 am in summer and until after 11 am in winter. The picture, taken around noon in June also serves to clearly show the worst location to be in shade while the best location (in Red) to be insolated. Whether a small PV component at the northern and southern extremes of the annexes is worthwhile is yet to be judged.