Analysis
Heat the Person, Not the Room
A plug-in space heater draws up to 1,500 watts to warm air you leave behind when you stand up. One side of a heated blanket runs on less than a tenth of that, and a heated vest on a few watts.
A space heater warms air. You are not the air. You are a person sitting in one chair, and the heater spends most of its effort on the corners of the room, the ceiling, and the gap under the door.
Put the published wattages side by side and the difference is not small.
| What it heats | Product we compared | Published figure | Average draw |
|---|---|---|---|
| The room | Any of the four space heaters | Up to 1,500 W on high | 1,500 W |
| One side of a bed | Bedsure heated blanket | 100 to 110 W per controller | about 110 W |
| Your torso | Gerbing Torrid vest, high | 25.16Wh for 2 hours | about 12.6 W |
| Your torso | Venustas Classic vest, low | 37Wh for up to 10 hours | about 3.7 W |
| One foot | Venustas heated socks, low | 19Wh per battery for up to 14 hours | about 1.4 W |
The battery rows are averages, worked out by dividing the stated watt hours by the stated hours, so treat them as orders of magnitude rather than measurements. Even so, the spread runs from 1,500 watts down to under 2. The heater on high draws more than a dozen heated blanket sides at once, and several hundred times what a vest uses on low.
Why the small numbers work
A heated vest does not have to raise the temperature of a room. It sits against the place where you lose heat, and the insulation around it keeps most of that heat where it is made. A blanket does the same over the whole body while you are still. A heating pad does it at one point, with a 2-hour auto shut-off on every pad we compared.
The idea is not new. The US government’s FuelEconomy.gov advice for electric car owners in winter makes the same point in a different setting: using the seat warmers instead of the cabin heater can save energy and extend range. Warming the seat is cheaper than warming the air in the cabin. Your living room works the same way.
Where each one fits
At a desk. A heated vest or a heating pad behind the back. The vest moves with you; the pad needs a socket. The vests we compared publish very different battery sizes, from 37Wh on the Venustas down to about 16.7Wh on the Mobile Warming Peak BT, and their runtime claims are for the low setting. Read the watt hours, not the hours.
In bed. An electric blanket, ideally with dual controls so two people can set two temperatures. All four blankets we compared have them on queen size. Bedsure lists a default 8-hour auto shut-off across its current heated blankets, which matters more for a product you fall asleep under than any fabric choice.
On the sofa. A hot water bottle or a heating pad. A hot water bottle uses no electricity once filled, and the better ones publish their safety standard: Hugo Frosch’s page names BS 1970:2012. Follow the fill rules. Both Hugo Frosch and Fashy say two thirds full at most, and Fashy says never boiling water.
Cold feet. Heated socks, with the caveat that the spec sheets vary widely. The Venustas socks publish their three temperatures, 113, 122 and 131 degrees F, while the Gobi Heat Roam page gives runtimes that contradict each other.
Stop paying to heat the draft
Personal heat solves your comfort. It does not solve a room that loses heat as fast as you add it, and the cheapest fix there is a seal, not a heater.
A screw-on sweep like the Frost King aluminium and rubber model closes the gap under an exterior door, and its maker guarantees the rubber’s weathersealing for life. For leaky windows, a shrink film kit like Duck’s rolled film covers five windows from one roll and comes off in spring. Both cost little next to a winter of running a heater against an open gap. The fabric draft snake is the weakest of the options we compared, because it sits loose and moves every time the door is used.
When the room still needs heating
Personal heat is the wrong answer in three cases.
Shared rooms. Five people watching a film cannot all wear the same vest. If several people use a room together, warming the air is efficient again, because the air is what everyone shares.
Plumbing and cold surfaces. A pipe on an outside wall does not care how warm you are. Neither does a cold wall that collects moisture. The EPA lists condensation on windows, walls or pipes as a sign of high humidity worth acting on, and a room kept cold enough for that to happen needs background heat as well as a dehumidifier or ventilation.
Children and sensitive skin. Young children and anyone with sensitive skin need a different plan, and the hot water bottle makers say so. Hugo Frosch says its bottle is not suitable for children, and Fashy sets a lower surface temperature for children and sensitive skin.
If you do run a space heater, the US Consumer Product Safety Commission’s winter guidance is short: keep all sides at least 3 feet from beds, curtains, papers and sofas, plug into a wall outlet and never a power strip, put it on a stable, level surface, and do not leave it running unattended in a confined space. Our space heater review says the same about the extension cord.
The order to spend in
Seal the gaps first, because a door sweep or a roll of film works every hour of every day without drawing power. Then heat yourself, with a blanket for the bed and a vest, pad or bottle for where you sit. Keep the space heater for the rooms where several people gather, and set it to cycle off once the room is warm. The space heater comparison found little difference in running cost between models, since every one draws up to 1,500 watts on high. The real saving is deciding how often it needs to be on at all.
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