Guidebook for Energy Efficiency in Municipalities

air supply at the beginning of each winter day, to warm-up the building at maximum
efficiency.
Energy distribution systems: Pumps circulating chilled or heated water, as well as fans
blowing air through ducts, often consume as much energy as is used to heat and cool the
building. Furthermore, ducts and pipes are often inadequately insulated, so much of the
cooling or heating energy may be wasted during distribution. In large buildings, both
heating and cooling systems often operate at the same time because of variations in
temperature throughout the building. This further increases distribution energy losses.
Control systems monitor the heating and cooling requirements of the building and vary
the operation of the HVAC system to maintain comfort. At its most basic, a system may
have a simple thermostat. Sophisticated systems involve time controls, humidity sensors,
CO 2 sensors and optimisation systems, and may be part of a complex Building
Automation System (BAS). In large buildings, control systems may operate heating and
cooling systems at the same time, in response to conditions in different parts of the
building; these systems often work against each other.
Heating and/or cooling equipment varies in scale and complexity from a simple wallmounted
air-conditioner, through standard ‘packaged’ modular units, to large and
complex systems with boilers to provide heat, and chillers and cooling towers to provide
cooling. The more complex the system, the larger the energy losses from the associated
equipment, such as fans and pumps, and from the distribution system will be.
Ensure that the system is maintained properly
Even if the HVAC equipment in a building is properly commissioned after construction,
performance deteriorates over time. Thorough maintenance programs can therefore bring
substantial, cost-effective savings. Where maintenance is carried out under contract,
make sure the contract is sufficiently detailed and supervision is adequate to ensure that
maintenance is done properly.
In smaller buildings, maintenance activities might include:
checking thermostat settings, calibration and correct operation, including sensors and
controllers away from the plant room;
checking the setting of controls including time switches and selector switches;
checking the operation and settings of economy cooling dampers and controls;
regular cleaning or replacement of filters in air-conditioners;
checking for leaks or deterioration in insulation of ducting;
sealing of air leaks around doors and windows.
Optimise the operation of pumps and fans
Large savings can be achieved by installing variable-speed motor drives, so pump and
fan speeds can be matched to requirements. The savings are disproportionately large:
halving the flow rate in moderate weather theoretically cuts pump or fan energy
requirements to one-eighth.
Further savings can be achieved by:
cleaning filters, fans and dampers regularly;
checking and lubricating or replacing bearings;
ensuring that drive belts are in good condition, evenly matched and correctly adjusted;
installing high-efficiency, appropriately sized motors when replacement is needed,
and installing variable-speed drives where loads on motors vary;
fitting time switches or more sophisticated controls and using them to shut down
cooling/heating in areas and at times when it is not needed.