# Passive Design and Comfort
A building needs to provide thermal comfort to its occupants. The building envelope shields occupants from unwanted heat and passively facilitate the addition of required heat and removal of unwanted heat. The HVAC system then actively add or remove heat to maintain spaces at a thermally comfortable condition for the occupants. How much heat needs to be removed or added is dependent on what thermal conditions are comfortable for the occupants. A thermal comfort model is used to help designers determine the conditions. The 6 main factors used in thermal comfort models are air temperature, mean radiant temperature (MRT), relative humidity, air movement, metabolic rate and clothing. We will be using the CBE thermal comfort tool to decide what are the comfortable thermal conditions and use it in simulation.

