What if you could reduce your equipment tonnages and save $200 to $700 per unit or 15% to 25% on your equipment costs with a potential 1,500% ROI? Would you do it?
Construction codes are requiring better windows, more insulation, and cool roofs. Some buildings can take advantage of thermal massing and shading from architectural design. As a result of this (and depending on climate zone), many buildings can reduce heating and cooling equipment tonnage to lower first costs.
Before energy efficiency was an important element in a building’s design, the common practice was to follow rules of thumb to prescribe system tonnages for HVAC systems. Those rules of thumb would usually simplify the process of calculating the tonnages required by the spaces, and would tend to favor oversized systems that would be more than able to deal with the requirements of the spaces. The issue with this approach is that oversized tonnages are conducive to higher expenses and an overall lower energy efficiency. Higher prices upfront, higher expenses in maintenance due to short-cycling, higher energy use, and higher sound levels are some of the problems derived from oversized equipment.
A way to approach this challenge is by performing what is known as ACCA Manual J calculations, which could be seen as “tailor made” calculations of the tonnages that will need to be met by the systems. These calculations are detailed enough to account for the specific characteristics of the spaces, putting speculation and vagueness aside and illuminating an area of financial and energy savings for each residential unit and occupancy.
VCA Green provides services for ACCA Manual J, Title 24 & ASHRAE energy modeling, and other forms of California Energy Code consultation. For more information, contact Moe Fakih below.
Contributing Writer: Alejandro Gamas, CEA, HERS Rater
Moe Fakih, Principal