So much going on - where to start

The stimulus package has had an incredible effect on the housing and remodeling industry. For example there is a tax credit for renewable energy systems equal to 30% of the cost of the system. http://www.energystar.gov/index.cfm?c=products.pr_tax_credits


This has prompted a fair amount of interest in solar hot water systems and geothermal heating and cooling. But, does it make sense to spend money on these systems if the home they are being installed in is insulated poorly or perhaps is leaky?


If a homeowner can reduce the demand for heat or air conditioning in a house by insulating it and sealing it up first, then smaller heating or air conditioning systems can be used. This can, in turn cut the total cost of the system and increase the payback time substantially.


For expample if a homeowener is installing a geothermal system in a home, and the home is sealed up tight, it will take less energy to heat the home and likely less cost for the system. On the other hand if the home is not tight and leaks air, the heating or cooling load may have to be increased to accomodate the leaks in the house. If that results in another well having to be drilled or another solar panel being added or the backup furnace coming on more often, where is the savings?


Wouldn't it first make sense to spend a substantially lesser amount of money on sealing a home up tight?