Understanding Why You Should Enclose and Encapsulate Your Building Environment Envelope First Before Installing a New HVAC System?
Should you spend your money on a better building envelope (whole outer shell of my home air barrier and insulation) or on high efficiency air conditioners, heat pumps, or furnaces?
It’s all stuff to help cut down your energy bills, right? True, but there’s definitely a preferred order (when you have the option). Ironically, the more efficient the whole house shell [envelope] is, the harder it is justify expensive high-end HVAC systems.
Here’s the way to look at this.
- The building envelope [whole outer shell] reduces the amount of heating and cooling your home needs.
- High efficiency HVAC equipment reduces the amount of fuel you need to meet the heating and cooling needs. If your house is leaking like a sieve or like pouring water through a collander, then your HVAC will just keep running, and running and running, dumping more expensive cool or heated air into your house while 40% or more is leaking up through your ceilings and roof almost as fast as you can pay to pump it in.
- Remember you can put an HVAC system out in the middle of your backyard, turn it on and it will run and blow out hot or cool air right into the open air outside your home, right up and into the open air.
- Your electric and natural gas bill will be sky high. When you call out the HVAC man and ask, “what’s up”? He will say “your unit is running just fine!”, the problem is you are trying to cool or heat the whole open out doors. You need to enclose the open sky. Well, knock me over with a feather, “enclose the area”, “create an enclosed area of which to contain that hot or cold air and keep it inside the “envelope” for as long as possible. Well then enclosed the space with foam as it has the highest efficiency available and Viola’ you have a cool, conditioned, enclosed space where the hot or cool air “stays in”.
- Do you want to keep sucking all of your hot and cold air up and out your attic? If not then address your homes building envelope first. Seal up the attic and floors. Stop the “stack effect” with spray foam.
Think of your house as a basketball game. The HVAC system is your offense. The “Sealed building envelope” is your defense. You might have an amazing offense, but if you keep getting clobbered on defense, you’re going to wear yourself out on the offensive side just trying to stay in the game. The better your defense, the less you have to rely on a high-powered offense. And you know what they say: “Offense sells tickets; Defense wins championships.”
When talking about the effective use of super insulation material like spray foam, the building envelope reduces the amount of heat flow between inside and outside to such a degree that the house needs little heating and cooling energy to keep the living environment at the level you set at the thermostat.
So, as odd as it sounds, the more energy efficient the home is, the less sense it makes to put in high efficiency HVAC systems [the most costly choice] as your first step. Do as much as you can with the building envelope “BEFORE” you tackle the HVAC side of the equation. If you start with the heating and cooling equipment, you’ve probably lost the battle before you’ve even begun.