Cold on the first floor?

We've definitely had a cold snap recently, as most DCists can attest while standing outside to watch many of the outdoor inauguration festivities. This past Friday I was having lunch with my close friend, Megan, and we were discussing our personal sagas living and working in old DC homes that are frigid on the first floor, and hot on the second floor.
Megan is an architect (doing some really interesting things with her firm Suzane Reatig Architects www.reatig.com) so we got to talking about the reasons and solutions for drafty and chilly temperatures on lower floors in many old homes in DC. Conversely, summer time can be brutally hot when your bedroom is on the top floor of one of these old structures.
Beyond the obvious- that heat rises- there are several things that contribute to the temperature differentials in homes, as well as opportunities for mitigating them.
Most importantly, it's important to realize that air is constantly swirling around within a home. It moves through cracks in walls, holes in drywall, gaps created by light fixtures, and poorly insulated floors, walls and ceilings. Most often, the cold air comes up through a cold unconditioned basement or through a vented roof eave.
On any given day when the temperature drops below freezing, our apartment (which we rent) might just be colder than our refigerator :). Unfortunately, the original contractor put absolutely zero insulation in the walls and flooring. The result- coldness. The solution- seal the basement with an air barrier insulation. This type of insulation- which is often sprayed by professionals will not only insulate (like traditional fiberglass insulation), but it will also prevent air from traveling from those cold areas into your home. Additionally, several options exist, including a product called Icynene as well Bonded Logic. These products are superior to traditional fiberglass insulation because of their ability to act as an air barrier. Some of these products contain high levels of recycled content and or organic material such as cotton.
Of course, during a renovation, whenever walls are torn down, always consider adding insulation with thermal and air barrier properties between wall cavities and floor cavities. The insulation will help reduce the movement and entry of hot and cold air that create uncomfortable (and inefficient) temperature variations in your home!