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Another case of balancing your thermal envelope is in terms of window quality. Having an extremely well-insulated wall is great, but if you blew the budget on insulation and had to put in low-quality windows, they become the weak link in the chain and you can effectively undo all your own efforts to reduce heat loss.

So in the case of a super-insulated wall with cheap windows, the loss of thermal performance of that entire wall section (windows included) may have been a more expensive option than reducing the insulation level slightly and applying that money to a much higher quality window.

1- Be conscious of the use and type of exterior framing members. Some of the wood used in exterior framing can be safely eliminated - headers on non-load bearing walls, unnecessary cripples, redundant studs in corners etc. 

2- Avoid metal fasteners of any kind that span the entire wall assembly.

3- Design your basement wall so it is better protected against moisture and water damage. This can allow you to use wood instead of switching to metal as a durability precaution. 

4- Leave metal stud cavities on exterior walls empty, and instead use the money you would have spent on batts to thicken up a seamless layer of board insulation. You may lose a couple of inches of interior space, but that space would be more comfortable and you will get a much better return on your insulation investment.

1 - As warm air leaks out it is replaced with cold air, and 2 - if you think of the 'wind chill' effect, a drafty house means a warmer overall temperature will be needed to feel comfortable, so your thermostat will likely be set higher. The cold emanating from exterior walls and windows can be so extreme at times that it causes a noticeable air convection, creating the sensation of a draft. How do we combat this? Again, we end up cranking the thermostat higher until we feel comfortable.

RADIATION (in this non-nuclear case) refers to heat transferred through electromagnetic waves, particularly in the infrared spectrum. Heat emanates from any warm body, like the sun, a wood stove or a window, for example.

Cold surfaces absorb more than they radiate, so the net effect is a sensation of cold when you stand in front of a cold surface, even when the air is warm. This effect is especially noticeable with windows of lower quality, and walls that are not well-insulated.

CONDUCTION refers to the heat that moves through solid materials, like your insulation or the wooden studs on either side of it. When a high-conducting material like concrete, metal or wood spans an entire wall assembly, it provides easy passage for heat to leave your house. This is known as a 'thermal bridge', and preventing it is known as a 'thermal break'.

Heat loss through thermal bridging

When we mentioned at the beginning that these factors can work in conjunction, that is because the cold surface that results from the high conduction through wall studs and other thermal bridges can absorb radiation and create convection heat transfers as well. It sort of seems like cold is conspiring against you doesn't it? That's because it is.

So those are the three main factors that will determine how comfortable your home is, or more accurately how much you will have to spend to keep your home comfortable.