Why do a Heat Loss?
Well - simple. If you are heating any space or home, you need to know how much heat is required to heat that space or home.
Every house is different as is every space. We have seen houses in Vermont (a very cold place) range from 10 btu a foot to as high as 90 btu a foot. Btu changes from room to room also, one house had a heat loss of 10 btu in a room with 8 windows and right next to it in a similar room and size - 45 btu a foot.
New houses in colder climates average about 25 Btu's per foot. Houses from the 1970's average about 35 Btu's per foot. Houses prior to this - all bets are off. Of course - these numbers are averages and may not reflect your house.
Why the difference? Houses are better insulated today that even 10 years ago. But your exact Btu heat loss? Hard to tell - but we know that it was due to several factors that would have been difficult to calculate without walking the space or using a good heat loss program.
So - How much do you need? Get a heating contractor to walk your space or download a HVAC-Calc Easy heat loss/heat gain software program.
What type of systems require a Heat Loss?