HVAC Basic Concepts

Heat Transfer

Heat Transfer between two bodies take place whenever there is a temperature difference, similarly Heat & Cold transfer occurs between Buildings & environment.

Heat will always flow from hotter side to cooler side.

During the summer, the environmental temperature is at its highest temperatures and heat from outside will flow indoors mainly through roof, windows, and walls.

Similarly cold transfer take place whenever there is a temperature difference between two bodies and cold moves to the warmer side.

During Winter the environmental temperature is at its lower temperatures and inside of building at a higher temperature, thus cold will flow indoors mainly through windows and walls. This situation continues till equilibrium achieved, with your HVAC use.

Attic space

Heat & Cold transfer occurs between the AC duct/chilled water pipes with thesurrounding environment. These pipes also are inside the building or running through shaft. This is also the case with hot water pipes through the walls.

Usually ducts are surrounded by internal environment/attic space and mostly encased behind the ceiling.

Presence of humidity is an important factor leading to condensation formation on the duct & pipe surface.

Thermal Insulation plays a role for stopping condensation happening.

 

Effect on your HVAC

Because of all mentioned before, the temperature inside the building increases.

The inside temperature might even go above outside ambient.

The inside temperature might even go above outside ambient. Because of this heat, the HVAC load increases

To be able to keep the indoors comfortable, the running time of compressors increases.

The end result is that you either have to increase your HVAC capacity and/or increase your energy consumption = increase on your monthly energy bill.