We just got our heating and air conditioning system hooked up and running at the end of the week. To be honest, we haven’t needed it as we have been leaving all the windows open at night to cool the house down. When we get there in the morning, we shut all the windows. With the house being so well insulated, it has been staying in the low seventies inside even when it’s over ninety and muggy outside.
For, the HVAC system, I sort of take things for granted and really don’t think the things we are doing are that amazing. Anybody building to earthcraftt or leed standards is already doing all of this. In the little bubble of friends and like minded builders, it already feels like the norm and not a big deal. But, lot of people are not doing these things, so running through some of the things we did:
properly sized the duct work for each space and properly sized the equipment based on the manual j calculation. Lot of HVAC folks still like to rule of thumb of it rather than sizing things appropriately. Our HVAC guy had two seperate programs run the calculation. One came up with a load that needed a 3 ton heat pump, the other 2.5 ton. We intentionally went with the undersized as it is more efficient and if you oversize a system you leave open the chance for cooling off a space too quickly and not taking the humidity out.
We went with a variable speed air handler, meaning the blower motor ramps up slowly rather than blasting all at once. More efficient, quieter. We made sure to get equipment that met the Federal Stimulus package qualifications for energy efficiency to receive the $1500 tax credit to the homeowner.
With the house being so tight because of all the spray foam insulation, indoor air quality can really suffer as you can easily end up with stagnant polluted air. Pretty much, if you are working with foam, whether it be SIPS, spray foam, superior walls, you have got to introduce fresh air.
We went with a ventilation control that introduces fresh air directly into the return plenum of the air handler. It’s got a damper on it that that is electronically controlled to open at proper time intervals. It also has a temperature sensor and a humidistat, so that it does not open up it is incredibly humid outside in the summer, or below freezing in the winter. Now they also make a control that costs about three thousand more that conditions outside air on its way in, which is awesome, but I can’t find anything quantifiable that you will ever make your money back on that. The folks at Oak Hill National Labortories are doing some pilot homes where they are trying to achieve a zero energy home and they are just going with the same type we are using, so I feel fine about copying them.
Honestly, the big thing I want to push myself in the coming years is to make the move towards geo thermal because of the greatly increased efficiency and durability of the system. While removing the cap on the tax credits is great, the expense is still prohibitive. I’m hoping as more people move to it, it will bring the cost down in the coming years.