Residential HVAC System Sizing

Heating, ventilating and air-conditioning (HVAC) system sizing for existing single family residents in hot and humid and temperate climates present different problems. In hot and humid climates, the proper sizing of residential air-conditioning systems is an important issue, since if the system is over-sized the resulting mold problems can cause significant problems with occupants who are susceptible to airborne spores like mold that can severely affect their asthmatic illnesses.
In more temperate climates, HVAC system sizing for existing single family residential unit is primarily concerned with heating systems. However, there is often a need to retrofit the residential unit with an air-conditioning system.
The technique for properly sizing residential air-conditioning and heating systems is based on methods described in the ASHRAE Handbook of Fundamentals. Heating and cooling spreadsheet programs that duplicate the methodologies were developed and have been used to evaluate the design cooling load for a number of single family residential units (condominium and homes) in Florida and in New York and Massachusetts. Two examples, a condominium in subtropical Tampa, Florida and a condominium in temperate Albany, New York are presented and discussed. Conclusions and recommendations are made on the sizing criteria for residences in these two diverse climates.