On average, HVAC systems contribute approximately 70% to a building’s energy consumption. Chillers, compressors, fans and pumps are the highest users of energy. Heat loads are primarily from roofs, windows, outside air, people, lighting and infiltration.
A HVAC system is designed to move heat to maintain comfortable conditions within the built environment. Heat is moved out of a building in three stages:
Each step is completed in different ways depending on the system which is installed.
1) COLLECTION: Five main methods are considered. Four can be designed to deliver an efficient solution to suit the space except for constant volume system, which is not an efficient long-term solution. They include:
2) TRANSFER: Compressors are the main facilitator for heat transfer. The key types of compressors are:
There are three common types of non-centralised HVAC systems:
A stand-alone air conditioning system located on a roof which takes hot air from the building and returns cool air. They are easy to access and maintain with all parts in one place. Newer units are relatively efficient and can incorporate an economy cycle.
Similar to a split system but instead of the indoor unit mounted on the wall it is located in the ceiling space with air ducted to and from it. Multiple rooms can be fed and they are generally used in larger room spaces.
The requirements that consider whole of life efficiency including maintenance, servicing energy and water consumption should include: