The last time your commercial building needed an HVAC upgrade, your selected contractor determined how large a system to install — and that decision likely occurred in a troubling way.
Imagine a certified energy auditor running sophisticated computer models or factoring in weather patterns in order to ensure that the building had the right amount of heating and cooling. Perhaps there’s even some new on-site energy analysis tools that contractors can use to come up with efficient solutions on the fly.
At Bay Efficiency, we were intrigued to learn what goes on behind the scenes — so we asked our HVAC contractor friends.
The answer: find out how much is needed to cover the building’s square footage, and double it.
An old, flawed way of calculating HVAC sizing
This old method for determining the size of HVAC systems dates back to a time when buildings were designed without the use of computers.
Contractors then didn’t have the tools to calculate the exact amount of heat and cooling that was needed — so they built the systems twice as big as needed to account for all unknowns.
That old way of working is still engrained in standard practice. Even with modern technology and the ability to conduct commercial energy audits, contractors still find the square footage (or reviewing the existing system in place) and simply double it.
That’s a problem. This method doesn’t account for the number of people inside, the shape of the building, the ceiling height, the building’s climate zone, exposure to sun, and more.
Energy analysis can lead to better results
To be fair to the contractors, accounting for all of these variables requires complex energy analysis and modeling. Even worse, accounting for only some of the factors could lead to an HVAC system that is undersized and doesn’t meet the building's needs. The “2x rule of thumb” plays it safe.
But this safe approach — installing twice as much heating and cooling as you need — also costs about twice as much.
At Bay Efficiency, we believe that energy audit services are the key to changing this method. It doesn’t take long to audit the facility and produce a building energy report that shows precisely how large the final system needs to effectively heat and cool for years to come.
The benefits are too big to pass up. By installing what you need — instead of double what’s already there — you’ll end up with a final system that is both energy efficient and cost-effective.
Rather than continuing with the status quo, tell your HVAC contractor you want to conduct an energy audit (and let us know if you need any help). It could save you up to 50% of the final cost.