Energy Management for Sustainability
1. A building in Adelaide, Australia has 210 m2 of exterior 6 mm single clear glass with no
interior shading. The inside design condition is 25 °C. Determine the net conduction heat gain
through the glass at solar noon on the design day.
2. A room in a building in Brisbane has a 4 m W by 2 m H window facing North. The building
is of medium-weight construction. The window is 6 mm single clear glass, with dark roller
shades. There is a 1 m outside projection just at the top of the window. Find the solar cooling
load through the window at 12 noon and 3 pm on 1st Jan.
3. Discuss what phase change material is and how it can be used to heat and cool a space.
(200 words)
4. You have measured the ventilation in a large truck bay and have found that you are using
5,640 l/s outside air. An analysis shows that only 3760 l/s are required. Measurements at the
fans give the total electrical consumption of the ventilation system as 16.0 kW at current flow
rates. You are currently ventilating this area 16 hours each day, 250 days each year, including
the times of peak electrical usage. Your monthly electric rates are $.20/kWh and $10.00/kW
of demand. (Source, Guide to Energy management, 4th Ed. Pages 528-529) (Hint: Power
needed can be approximated as directly proportional to volume flow rate cubed.)
a) Assuming that your power factor is 90% and that your marginal electrical costs are at
the least expensive rates, what is the amount of annual savings that you can expect by the
proposed reduction in ventilation rates?
b) After implementing the improvements suggested above, you decide to analyze the
value of having the second shift come in just as the first shift is leaving, thereby reducing the
amount of time that ventilation is needed by 1 hour each day. How much annual savings do you
expect this measure to achieve?
5. In an open floor air conditioned building, a work force of 18 people including 4 overhead
personnel, practically seating during the day, 4 maintenance personal and supervisor, and 10
people doing heavy labour, works 8 hour a day.
Estimate a) the total cooling load associated to occupancy.
b) The peak load contribution of the HVAC system to remove the occupancy heat
load. Assume the EER of the system is 3 and runs continuously during the occupancy hours.