A load calculation determines a home’s heating and cooling needs and informs the size of the HVAC system required.
Load calculations were once conducted manually; so many HVAC contractors skipped this step and made assumptions based on square footage. As you can imagine, this guessing method doesn’t offer precise information and can lead to a home being burdened with oversized and inefficient HVAC equipment that compromises home comfort, wastes money and energy.
Within the building industry, there are a number of modelling practices, technology and software approaches with varying degrees of sophistication available to HVAC contractors and builders to guide the selection and design of HVAC equipment. Current industry practices range from the guestimate method mentioned above (X BTUs per square foot) to spreadsheet models (e.g. TECA Quality First™) to NRCan’s HOT2000 to HVAC Design software (e.g. Wrightsoft) and others.
Thanks to advancements in technology, load calculations are now computerized, making it easy for a qualified mechanical HVAC designer to create a digitized model of your home and deliver exact results.
This valuable information helps builders, architects, designers and homeowners create extremely energy efficient, cost-effective, HVAC systems, and plan ahead for how to fit them seamlessly into the home design.
To avoid disappointments and issues that arise when HVAC systems are oversized, be sure to avoid the ‘rule of thumb’ method, and work with professionals who understand and use load calculation tools that meet the F280- 12 standard. This is a Canadian Standards Association (CSA) standard on how to properly size HVAC equipment. It is nationally recognized and referenced by all Canadian Building Codes.
The new F280-12 standard addresses the shortcomings of the original standard published in 1990 that resulted in the oversizing of residential HVAC equipment and ductwork and accounts for the evolution of building codes and growth of high performance homes in Canada. (Read more about CAN/CSA F280-12: Determining the Required Capacity of Residential Space Heating and Cooling Appliances)