Gas or Electric Heat?

It gets cold (and hot) in Minnesota, where I live. Therefore, the workshop must be well insulated, heated, and ventilated.

The walls are framed from 2× 6 studs, which provide enough depth for R- 19 insulation, and the windows are double-glazed.

I briefly considered a hydronic radiant floor heating system. A hydronic system uses in-floor, hot-water-filled tubing to heat the room from the ground up. I knew that the concrete slab floor would be cold, and that a hydronic system would make the room warm and comfortable. But the hydronic system has a longer heat-up time and much higher initial costs. This swung the decision toward a fan forced-air heater mounted in the rafters.

But is gas or electric a better choice? A good case could be made for either. Deciding which made more sense was a study in what my old college professors would term engineering economics.

Electric heaters are 100% efficient, that is, all the energy input goes toward making heat. Gas heaters are about 80% efficient. To account for the gas inefficiencies, I divided the gas cost of 3. 4 cents/k Wh by 80%, yielding a net cost for gas heat of 4. 2 cents/k Wh. Bottom line: where I live, gas is 3 cents per kilowatt-hour less expensive than electricity.

Step 2. Determine initial costs. So, the smart money goes with gas, right? Well, not necessarily. While comparable-sized gas and electric heaters cost about the same, gas line installation can be expensive. The contractor quoted a price a bit north of $1,000 to trench, plumb, and install a gas line to the workshop.

Illustration by Katie Wilson

Step 1. Determine operating expenses.

To make a solid financial decision, I needed several pieces of information: the relative energy costs for gas and electricity, the purchase costs for each type of heater, and the efficiency of each.

I studied my utility bills to determine comparable energy costs. January natural gas costs me about $1.10 per therm, a therm being the energy equivalent of roughly 29 kilowatt-hours. So $1.10 divided by 29 equals a gas heating cost of 3. 4 cents per kilowatt-hour. The local energy utility charges 7. 2 cents per kilowatt-hour.

Step 3. Compute the payback period.

$1,000 divided by $0.03/k Wh = 33,333k Wh

The heater I’ve chosen operates at a maximum of 5 kilowatts. So, each full hour of use costs 15 cents more if I use electricity instead of gas. Dividing $1,000 by $0.15 per hour computes to 6,666 hours of heater use. Given the relatively light use of the shop, the payback period on the installation of a 5k W gas heater would be decades, so I invited Reddy Kilowatt into my shop.

NEXT: In Volume 13, Gurstelle explains shop organization.

Make: 37