My 101-year-old Victorian home is extremely well-built — it's as solid as a rock and it weathered Hurricane Sandy as well as the most recent snowstorm with nary a groan. Although it's a classic, it's not exactly energy efficient. Last fall, I got an energy audit (because of the age of the house and the possibility of asbestos, we couldn't do a typical blower-door test) which helped me understand where there were leaks and holes in my home's shell (and where I'm losing heat and energy all winter long). You can see the video of the audit below, plus lots of great details.
Between the making of the video and some subsequent research, I found out that there are two natural ways to detect drafts and heat loss from a house, no fancy equipment needed. First, spiders always situate themselves near drafts, even minor ones. So if you want to figure out where errant drafts are (especially in ill-used areas like basements and attics), look for the windows or spaces that have webs in front of them. Clean up the spiderwebs, seal up those windows and spaces, then wait to see if the spiders come back and you'll know if you fixed the issue.
Icicles are another natural indicator — in this case, of heat loss. I tweeted a picture of the icicles hanging from my roof, and a fan of my site mentioned that I was probably losing heat through my roof. According to energy360solutions, "When hot air rises and your attic is not properly insulated, the hot air melts the snow near the peak of the roof. The melted snow runs away from the heat and freezes towards the end of the roof or gutter." The good news is that I used to have a whole row of icicles in that spot, and now there are only a couple, so the fixes I made in the video above (sealing cracks and closing up a large holes in my attic walls), have probably made a real difference.
Related post on MNN: Urban vs. rural: Which is more energy-efficient?