I recently moved into a new construction home where there are rooms above the garage. I've read several articles about how you can add insulation, but I am trying to figure out what I should reasonably expect by default.
The home also has two-zone hvac where upstairs is on it's own so I am expecting better than if it was one zone for the whole house.
I used a infrared thermometer (not expensive FLIR, but basic). Taking reading from the master bedroom where the thermostat is to the bedrooms above the garage, I get typically about 7 degree Fahrenheit difference.
So Far
Test Day 1 in Sep: 74 in the room with thermostat, 67 in the rooms above garage
Test Day 2 in Oct: 69 in the room with thermostat, 62.5 in rooms above garage.
Are there any standards or code which I should be checking? I want to have the builder do at least the proper minimum before I start shelling out from spray foam or something else. This seems like something is missing for such a big difference.
Edit:
I have not yet had the system blowing on full tilt for a long time for heat. Even on days when it was in the 70s outside, it would feel cold in the bedrooms, and the temp in the garage would actually be warmer. Maybe when the systems are blowing hard it will have an impact, but in the shoulder seasons when systems aren't blowing a lot I would expect closer temps across the floor in a new home.
Best Answer
Yes, there are energy efficiency code standards for residential buildings. The Code is divided into 1) one and two family structures, and 2) three or more residential structures. (There are also energy standards for manufactured housing, log homes, commercial, institutional, etc. too, but that does not apply here.)
I will reference one and two family structures only.
Each building department “adopts” their own “code”, but this is recognized throughout the U.S. This is based on the International Code Council (ICC), 2017 edition, which is the current edition.
First, you should know that the Code provides a “proscriptive path” for all building elements. If you use them, then you are approved for construction.
Second, the Code allows substitutions and “alternate means of construction “, but the calculations required to show you meet the Energy Code is difficult (and would probably require a mechanical engineer to do the trade-off calculations.) That is to say, you don’t have to use R-21 insulation in the walls, but if you don’t, you’ll need a more efficient heating/cooling system...etc.
So, here is a list (you can verify this list by calling your local jurisdiction...Building Department) and it doesn’t matter if you’re over a garage or not:
Note: R-values are for insulation ONLY. It does not include values for siding, sheathing, etc.
There are many other Energy Code requirements like : window air leakage, slab on grade performance, etc., but too numerous to list here.
SUMMARY: If your contractor met the above requirements, I’d expect better performance in your living space above the garage.
If the space is not too cold (in heating season) or not too hot (in cooling season), then the heating system is of adequate size.
I’d then check thermostat. Some have a “dead zone” setting...usually about 3 degrees. That is to say, if you set it at 70, then it must drop (or rise) 3 degrees before it turns the heating/cooling system on. If the thermostat is located in a drafty area (say by an exterior door) it could trigger the thermostat.
I would then check insulation thicknesses. One easy check is to see if the walls are made out of 2x4’s. The required insulation cannot be installed in 2x4 walls...a 2x6 wall is minimum. (You can easily check thickness of walls by looking at the walls by the windows.)
I’d check the ceiling insulation, because heat rises and you’ll quickly loose heat through the ceiling/roof quicker than walls. (Likewise, If cooling is an issue, then check the floor insulation. )
If the windows are not double pane or the exterior door does not have weatherstripping, then they do not meet minimum requirements.
Remember, your large temperature change is caused by a lack of retaining your heating/cooling AND your heating/cooling system not responding quick enough.