HVAC brochure - Eskom IDM

4.1.1 Replace leaky dampers
Many ventilation systems have low quality outdoor air dampers that do not permit accurate control of airflow.
Even when dampers are fully closed, the quantity of air leaking in may exceed minimum outdoor air requirements.
Leaky outdoor air dampers can be replaced with high-quality, opposed-blade dampers that have air spats at the
blade edges and ends.
4.1.2 Use separate make-up air for range hoods
Kitchen equipment exhaust hoods and other process equipment hoods that frequently remove large quantities
of conditioned air from a building must be replaced by introducing outside make-up air. To reduce the quantity
of energy wasted in pre-conditioning supply air to exhaust hoods it is often possible to install a supply air system
that is completely or partially separated from the rest of the building HVAC system.
4.1.3 Use economiser controls
Mechanical cooling is often used when outside temperatures are relatively acceptable.
5. Air conditioning and refrigeration
The purpose of refrigeration or air conditioning systems is to move heat from a cooler space to a warmer space.
In very simple terms, these systems move heat against its natural direction of flow.
The energy required moving the heat uphill from colder to warmer depends on two things:
• the temperature difference from cold to warm, and;
• the amount of heat the system has to move (the cooling load).
Blower
Compressor
Fan axle
Fan
OUTDOORS
Condenser coils
Hot air
Outdoor air
Cooled
air
Cooling coils
Temperature
sensing bulbs
Expansion valve
Indoor air
Figure 1: Typical air conditioning unit
5.1 Opportunities for improved efficiency: air conditioning and refrigeration equipment
One attractive characteristic of many air conditioning systems is that the system will deliver the cooling effect required
over a wide range of conditions. Unfortunately, the energy consumed in extreme conditions is likely to be more than
double that of normal conditions.
Often, extreme conditions result from inadequate or deficient operation and maintenance practices. Therefore, a
simple but effective strategy for minimising energy cost involves attention to operation and maintenance procedures.
4
124537ESKD HVAC brochure.indd 6
2010/09/10 9:53 AM