Purchasing a commercial HVAC unit for a building differs significantly from buying a heating or cooling system for a home. A commercial HVAC unit must be powerful enough to maintain a comfortable indoor temperature, even when doors and windows are being frequently opened and closed.
Determining The Correct Size Commercial HVAC Unit
To determine what size HVAC unit will be required for a building, several factors should be taken into consideration, such as the square footage of the building, the climate, and how many people are typically in the building on a day-to-day basis.
Use The Manual J Calculation
To avoid purchasing an HVAC unit that is too big, or too small for a building, several factors must be considered. The first step in determining what size commercial HVAC unit is needed involves undergoing a Manual J calculation. A Manual J calculation is often used by HVAC contractors to determine the heating and cooling loads of a building. With this information, a contractor can recommend the ideal capacity of the equipment needed.
The Manual J calculation is considered to be very accurate as it takes many factors into consideration, such as climate zone, square footage, ductwork, natural sunlight or shade, style and number of windows, number of people in the space, amount and quality of insulation, and presence of heat-generating appliances. Upon completing a professional Manual J calculation, an HVAC contractor will be able to determine how many British Thermal Units (BTUs) will be needed from the HVAC equipment.
Consider Details Like Climate Zone & Number of Windows
Climate is a major factor when determining what size commercial HVAC unit should be chosen for a building. As a general rule of thumb, more BTUs are required to cool or heat a building the further it is from the equator. However, other geographic factors should also be considered, such as evaluation. There are five climate zones in the United States, including:
- Zone 1: Consists of the most southern regions, including New Orleans, Miami and Houston. Zone 1 has a heating factor of 30 to 35 BTUs.
- Zone 2: Consists of California and the Southern cities of Little Rock and Atlanta. Zone 2 has a heating factor of 35 to 40 BTUs.
- Zone 3: Consists of Virginia, Kansas and Missouri. Zone 3 has a heating factor of 40 to 45 BTUs.
- Zone 4: Consists of New York, Boston and Chicago. Zone 4 has a heating factor of 45 to 50 BTUs.
- Zone 5: Consists of the northernmost area of the U.S, including the cities of Minneapolis and Buffalo. Zone 5 has a heating factor of 50 to 60 BTUs.
Along with the climate zone, consider how many windows the building has. The more windows a building has, the more heat is likely to escape. This is especially true if the windows are older. With this in mind, opt for a commercial HVAC unit with a number near the upper end of the heating factor range if the building has a lot of windows.
Shop Units According to The Calculations
Once the size of the unit needed for the building is identified, it is time to speak with an HVAC dealer about purchasing equipment. If the BTU required is between two sizes, opt for the larger size. Having a little extra power is fine; however, an under-powered unit or a unit that is too large should be avoided. Having too large of a HVAC unit will result in the unit shutting off frequently as it will cool or heat the building quickly. This can result in high energy bills and uneven indoor temperatures.
Size Matters to Save Money
Choosing the right size commercial HVAC unit for the building can save money in the long-run. While some people believe that buying a bigger unit is better, it can be more costly to operate. The same applies for smaller units. A heating or cooling unit that is too large or too small can cause utility bills to rise and the comfort of the building to fall. Ideally, the unit should not exceed 15 percent over the recommended BTU for cooling and no more than 40 percent over the recommended BTUs for heating.
Speak With The Professional Commercial HVAC Contractors
When it comes time to upgrade the current commercial HVAC unit, it can be challenging to choose new equipment. Size makes a big difference in cost, comfort, and overall efficiency in the building. If you are unsure about what size commercial HVAC unit is needed or require assistance in choosing a new commercial heating or cooling unit for a building, call the experts at Cool Works Co.