Turn Up The Heat!

Within a few months after moving in to the house, I started on a quest for home efficiency.  There are a lot of gizmos available to audit the efficiency of your home.  Some companies and contractors specialize in that.  The home inspector said our windows and insulation are all fine -- it's only a 12 year old house -- so I knew the efficiency improvements would mostly come from behavioral changes.

Last winter, I plugged a $5 webcam into a computer.  I was quite excited about it, too.  You may be thinking -- so what?

The webcam is pointed at a couple LEDs near our furnace.  The computer runs a program to determine what LEDs are lit up every 10 seconds.  The LEDs are as follows:

• Power -- ignored, but could be used to determine if there is a power outage since the computer is on battery backup.
• Electric heat -- Used as primary (unless load balanced or gas fails), computer records this.  This runs on a cheaper electric rate, so it's cheaper than gas.
• Gas heat -- Rarely used, but the computer records this too.
• A/C -- ignored for now, don't use it much anyway since we're naturists.
• Load Balancing in effect -- ignored, but could be used to detect if gas is failing.

The computer also records the outside temperature (from a weather station in town) and a few other metrics (like wind, sun intensity, rain).  All this data gets charted and reported daily, and I can process the raw metrics any way I want.  This includes giving me a daily cost in dollars.

This also lets me test a few common myths.

#1:  Setting your thermostat 1 degree colder can lower your heating bill by 1-2%.

One night last winter presented the perfect opportunity to test this.  From 11pm to 5am the wind was low, the sun wasn't out, we were sleeping, and the temperature steadily dropped from 32 degrees to -2 degrees.  The average furnace runtime steadily increased during this time as well.

In the end, I calculated that (for our house) there is a 2.36% increase in heating cost for every degree.  Note that since it's based on a degree delta from our thermostat setting to the outside temperature, a degree change outside is equivalent to a degree change inside.  Lastly, the resulting 2.36% makes sense.  We have a bigger-sized ridge-top country home, so I'd expect the percentage to be higher than a typical city home.

So when the bill normally reaches $300 mid-winter, and my partner wants it 10 degrees warmer so she can run around naked, I ask "Is the extra $80 that month worth it?"

#2: Turning down your thermostat during the day will save you money.

In my experience, this statement is true.  But I rarely do it because it isn't worth it.

During the day, the sun has a huge effect on your house.  Even when the sun isn't shining, there is still heat radiating in.  Your windows amplify this effect by acting like a greenhouse, despite most windows having a heat-repelling glaze to minimize summer cooling costs (I wish they didn't).  All-in-all, your furnace works way less during the daytime!  If the high temp outside is within 20 degrees of our thermostat temp, our furnace normally doesn't run while the sun is shining.

Changing the temperature has no effect.  The time the furnace is off while the house temp drops will be balanced out by the time it runs to bring the temp back up.  The savings you get is by reducing the delta.  (Inside temp minus the outside temp.)  Reducing the delta for 8 daytime hours will save money, but not much.  Literally pennies per week.  Buying a programmable thermostat to do this will never pay for itself.

On the flip side, employing the same tactic at night WILL save you more than chump change.  Your furnace works the hardest at night, when the temps are colder and there is no sunlight to help out.  Throw a few extra blankets on the bed and make a quick dash to clothing when you get up.

My ideal thermostat would keep the temp at 60 through the night, bump it up to 65 for the morning rush, let it sit at 60 all day, then crank it to 75 some evenings so we can run around naked (but only if it's a reasonable temperature outside -- we can stay clothed on the colder days).

#3: Open the curtains during the day to let heat in, and close them at night to keep it in.

I tried this and it didn't have any measurable effect.  Windows are fairly insulated, and once heat gets through them it will stay in.  (Unless you buy a shiny heat reflector to use as your curtains, like what is used for auto windshields.)  At night, the cool breeze goes right around or through the curtains.  (Unless you use blankets as curtains and tape them to the window frame.)

If you often have the curtains closed, and the sunlight hits them, it may be worth having two sets.  Have a light color for the summer, and a dark color during the winter.

Another great option that others have tested is the use of bubble wrap.  It's easy and cheap to put in, pays for itself within half of a heating season, lets light in, and also obscures the view.  Perfect for naturists!

#4: Turning up the thermostat more will make it warm up faster.  (Especially on a cold winter day.)

For most furnaces, they are either on or off.  When they are on, they warm up the house at the same rate no matter what the thermostat is set to.  I've witnessed this first-hand.  I can measure it if someone really wants me to.

I say "most furnaces" because I know of one exception.  My parents have a geothermal system which has a "low" setting for warming up the house a degree or two, and a "high" setting when the thermostat is further off.

Lastly, cranking up the thermostat on the coldest winter days is the quickest way to raise your bill.  But if you insist on doing this, there better be a party involved.  Bodies are wonderful heaters.  Having a mid-winter nudist party might be cheaper than you think -- as long as you have plenty of warm guests.