Heat Your Clothes, Not Your House

As we wrote two years ago, insulation of the body is more energy efficient than insulation of living space. Because of its excellent insulating properties, modern thermal underclothing makes it possible to burn the heating at much lower temperatures without sacrificing comfort or sex appeal. The potential energy savings are huge, and the costs are almost nil.

This low-tech insulation strategy can also be applied to heating the body. In use since World War Two, electrically heated clothes have become more effective and comfortable in recent years. While their use outdoors increases energy consumption, heated clothes have the potential to save massive amounts of energy indoors.

Electrically heated clothing is used by soldiers, adventurers, hunters, winter sports enthusiasts, bikers and construction workers [1]. Heated leather jackets were already used by pilots in World War Two. Bikers have used the technology for decades, using the battery of their motorbikes to supply the required energy.

The arrival of compact lithium-ion batteries has increased the performance and diversity of electrically heated clothing. There are now more types of heated clothes on the market: jackets, vests, pants, socks, underclothing, baselayers, sweaters, scarfs, shoes and gloves. Some have even become fashionable.

The energy for these garments is supplied by one or two relatively small and light batteries, hidden in a special pocket, which supply the lucky owner with some five hours of warmth. Some brands offer the possibility to plug in heated gloves or socks in a heated pants or jacket, so that they don't need a separate battery.

Carbon Fibres

Also new is the use of carbon fibres as a heating element. This material is flexible and can be inserted anywhere in the clothes without creating discomfort for the wearer. Carbon fibres are replacing embedded heating wires, which are rigid and heavy, break easily, and require more energy. Making use of low voltages for safety, electrically heated clothing comes with a button on the outside which enables the regulation of the heating system.

Unfortunately, electrically heated clothing doesn't save energy when it is used outdoors. Like most technologies that increase comfort, it increases energy consumption. The big advantage for people who work or play outdoors is that heated clothing keeps them warm during breaks in activity, when body temperature can decrease quickly.

Effective and Efficient

When used as a heating strategy indoors, however, electrically heated clothing is as sustainable as it can get. A fully heated wardrobe -- pants, socks, underclothing, shirt and vest -- has an energy output of 100 watts maximum. There's no need for the heating elements to get very hot because they remain close to the skin. An electric heater of that calibre used for space heating brings little comfort, even if it heats a very small room.

Using electrically heated clothing we could be more comfortable at even lower indoor temperatures than when using thermal clothing (which already offered heating till near-freezing conditions). Another advantage of electric clothes is that you need less volume and weight to stay comfortable. This effectiveness and efficiency of heated clothes has been confirmed by scientific research [2].

Electrically heated clothing can also be used without activating the heating elements -- the good insulation of the garments traps body heat, as with thermal clothes. In this sense, heated clothing is similar to a bicycle with an electrically assisted motor. Unlike electric cars or smartphones, the clothes don't become useless when the battery dies.

Wired or Wireless?

The only unsustainable feature of electrically heated clothing is its use of batteries. A wireless energy supply is very practical, but it would be perfectly possible to connect electrically heated clothes directly to the grid, just as you would do with your phone and laptop. It would function like an electric blanket or sleeping bag. Since many of us are sedentry, this is not as far-fetched as it may seem.

Kris De Decker (proofread by Deva Lee)

----------------------------------------------------------------------------------------------------------------------------------------------

[1] Some manufacturers who sell electrically heated clothes are Gerbing, Venture Heat, Columbia, Blazewear and Milwaukee Power Tools.

[2] A Review of Technology of Personal Heating Garments, Faming Wang et al., International Journal of Occupational Safety and Ergonomics (JOSE) 2010, Vol.16, No. 3, 387-404. This study also reviews other techniques to make heated cloths, such as phase-changing materials.

The first picture shows electrically heated pants from Venture Heat. The second picture depicts a heated sock from Grabber, and the third picture a heated jacket from Blazewear. You can also make your own electrically heated clothing.

Related articles:

• The revenge of the hot water bottle
• Insulation: First the Body, then the House
• The Revenge of the Circulating Fan: personal cooling
• Radiant & Conductive Heating Systems
• Restoring the Old Way of Warming: Heating People, not Places
• The Solar Envelope: How to Heat and Cool Cities Without Fossil Fuels
• Sunbathing in the Living Room: Tiled Stoves
• Short posts

---

Read Low-tech Magazine Offline

Read Low-tech Magazine with no access to a computer, a power supply, or the internet. The printed archives now amount to four volumes with a total of 2,398 pages and 709 images. They can be ordered in our Lulu bookstore.

---

Comments

[wallebot]

(1)

En este caso no necesitas baterias electricas, tambien se pueden usar baterias termicas.
Mezclando cloruro calcico con agua se produce calor. Se usa en cafes autocalentables.
Una solucion de acetato sodico hipersaturada se puede calentar. Permanece en un estado estable aunque se enfrie, pero con un golpe u otro evento empieza a cristalizar y generar calor seguro a unos 50º.
No conozco otras densidades energeticas, pero la Cal viva genera 3 veces mas energia que una bateria de plomo al convertirse en carbonato calcico.
Tal vez la oxidacion controlada puede ser otro fuente de calor.
Existian unos mecheros cataliticos sin llama los calentabas y te podias calentar las manos si te protegias con un pañuelo o tela.
Los posos de cafe tambien generan bastante calor durante dias o mas. Si se les añade fertilizante nitrogenado se reactivan y calientan.
Pero generan humedad y necesitan respirar.
Los submarinistas que utilizan regeneracion de aire, al elimnar el CO2 obtienen calor con una reaccion quimica con la cal sodada.

[Roddy Pfeiffer]

(2)

In 1978 the University of Saskatchewan was building superinsulated houses that used $50 of baseboard electric a year to heat. A year. In an area with 2X the heating degree days of NYC. No passive solar or ugly building shapes. They also did a lot of research retrofitting existing buildings to that standard. They used fiberglass insulation. Newer materials, especially foams, are available that are more efficient and compact, and provide their own vapor barrier. A simple, inexpensive air-to-air heat exchanger is used to keep the air fresh and maintain best humidity levels.
The world could cut petroleum usage and save a lot of money by using this technique, but it's not new or sexy and nobody writes articles about it. The best way is often the way not taken.

[-]

(3)

AN ELECTRIC SHEET (THIN ELECTRIC BLANKET) WORKS GREAT IF YOUR ACTIVITIES ARE LOCALIZED TO THE LENGTH OF THE CORD. AS FOR GETTING TANGLED UP IN THE CORD, PEOPLE HAVE USED ELECTRIC DRILLS FOR DECADES AND ROPE FOR THOUSANDS OF YEARS . IT'S JUST A MATTER OF GETTING USED TO IT.

[Dorinda Troutman]

(4)

How is this clothing cleaned? If it can be washed like normal clothing that would be great. If it needs to be dry cleaned, that too would be a negative on the environment.

[Josh B.]

(5)

Even more low-tech is to simply stock up on wool sweaters and socks, long-johns, flannels, etc. The benefits are more than financial, as hanging out around the house in cozy clothes is psychologically beneficial as well. Imagine how comfy it would be to spend all day at work with your flannels on underneath your suit or dress!

[Kris De Decker]

(6)

Comments are preferably written in English and lower case letters, thank you.

@ Roddy: be careful with foam insulation, it has lots of drawbacks:
http://www.treehugger.com/green-architecture/series-spray-foam-insulation-safe.html

The great advantage of heated clothes is that you can refresh the air in a natural way, by simply opening a window. Superinsulated houses are causing many health concerns.

@ Dorinda: with most heated clothes, the heating elements can be taken out of the garments before cleaning.

[Roddy Pfeiffer]

(7)

I think you missed the part of my post about changing the air with a heat exchanger. It's an off-the-shelf device that brings in clean air without losing the heat the you paid for. Foam insulation is now made from soybean oil and other natural ingredients. There are also foams made from minerals, like Air-Krete, the one Al Gore used on his house. Heated clothes require an electric element close to the skin and subjects the wearer to unnecessary electromagnetic radiation. I'm surprised that tree-huggers would even consider it. Intelligent people stopped using electric blankets decades ago. These clothes are the same thing.

[picard]

(8)

At which temperature in your house are you still comfortable with this (low) technologie? 15°C? 10°C? 5°C? 0°C? I guess that you will have a threshold. Beyond a low temperature you won't fill very well anymore, have you got any data on this?
"Superinsulated houses are causing many health concerns." have you got any data on this it sounds quite interesting.
Last thing i haven't seen you discuss (maybe i missed it) in your post about house insulation, the most efficient way to decrease the energy use for insulation would be decrease of the surface per persone!

[Kris De Decker]

(9)

@ Roddy

There exist healthy insulation materials, indeed, but they are generally much more expensive. And a heat exchanger does not solve the health issues of a superinsulated house.

I agree that the health risks of electrically heated clothes should be investigated. But electromagnetic radiation is already everywhere. It seems to me that most treehuggers use mobile phones and wireless internet. While some people are oversensitive to electromagnetic radiation, it doesn't seem to be a problem for most of us.

[Kris De Decker]

(10)

@ Picard

I do not have the required information to calculate the relationship between heated clothing, thermal comfort and indoor temperature. There are no "clo"-values available for electrically heated clothes (see the article on thermal underwear for more information about the clo-value of clothes). Someone will have to do an experiment using a thermal manikin, as scientists have done with thermal underclothing.

I am preparing an article about superinsulated houses, so more on that topic soon. But to give already an idea of the concerns, here is a quote from a study in the Netherlands:

"Examples of passive houses are analyzed to find indicators of emerging health risks. Potential problems are overheating, noise from installations, legionella contamination of domestic water buffers, low ventilation volumes, complex control mechanisms and lack of flexibility of ventilation services..... The two inspected cases reveal poor attention to inspection and cleaning of ducts. Pollution from deposited dirt in the system can become a health risk after some years."

http://www.google.es/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CDcQFjAB&url=http%3A%2F%2Frepository.tudelft.nl%2Fassets%2Fuuid%3A88fd72b2-f7ab-45ea-a403-ce367801cf3f%2F223700.pdf&ei=9SB-UpjUIKur0AX6zoD4BA&usg=AFQjCNHSCTHAv4zwYR8yV7zTyUS0grkwJQ&sig2=KSFC7JfZ8FOYm6UAlla8yA&bvm=bv.56146854,d.d2k

[Roddy Pfeiffer]

(11)

I am not aware of any health hazards from superinsulated houses other than humidity and stale air from lower ACH's (air changes per hour). These issues were solved 30 years ago nu air exchangers. they do not have complex control systems nor use more than a negligible amount of electricity. They do not have any of the problems you mention in your post. Please do not lump several types of home systems together and dismiss them all because some of them have problems. There are passive solar houses, passive houses, geothermal houses. etc. Superinsulated refers only to a house having a large amount of insulation to achieve savings. They use the ductwork found in central A/C to move the air through an air exchanger. No more maintenance is required than any central air system.

[Kris De Decker]

(12)

Roddy

The link I posted above goes to a 2008 report. So apparently the issue was not solved 30 years ago.

[Himbeerkuchen]

(13)

Hello Kris and Roddy,
two bits: the living comfort of superinsulated houses (as Roddy correctly states, more clearly referenced as passive etc.) depends a lot on the air exchange system. I live in one since 2008: a multi-tenant building with central heat exchanger for 14 apartments. The heat exchangers (any type, geothermal, air-to-air heatpumps, house-to-external heat exchanger and any other) typically save at least 5x the amount of energy that they consume.
I keep thanking the lord for my wife picking up the leaflet that ended up with us moving into this house. No more draught from open windows in winter, no more stale air, ever. Always warm in all rooms, even with heating radiators set at low-to-average settings.

Second item: electrically heated garments do not radiate electromagnetic waves if they are powered by a DC source (like a battery). Of course, this depends on the make of the garment. The classical issue with EM radiation is only with electrical heat sources that are connected to the AC mains.

[Rakaziel]

(14)

You do not take into account indoor plants. While it would be possible to switch to decorative plants that survive the seasonal outside temperatures, this approach still collides with effective vertical farming (keeping things warm enough for three harvests a year).

[Kris De Decker]

(15)

@ Rakaziel: couldn't you build a small greenhouse for vertical farming indoors and then only heat the greenhouse?

[Himbeerkuchen]

(16)

well... I think besides plants :-) there are other clear limitations. Just think about homes with small kids. Simply not an option. They need a warm floor to play on, they often change clothes (not compatible to this concept, as heated clothing will be substantially more expensive) and they grow, so you need to obtain new clothes often.
Heating the clothing instead of the home may be an option for households mostly with single adults, with limited social activities in their home. Maybe this is a viable option for researchers in the colder regions of the earth, as well as for construction workers in remote locations.

[Kris De Decker]

(17)

@ Himbeerkuchen: couldn't you build a small greenhouse for kids indoors and then only heat the greenhouse?

Just kidding.

Of course, there are limitations to the concept of heated clothing. It is not a solution for anyone, but it is also not the only low-tech heating option (see "related articles", and articles to come).

[Himbeerkuchen]

(18)

@ Kris,
thanks a lot. In any case, what I keep appreciating about Lowtechmagazine is the continued and radical out-of-the-box thinking that the articles show. Not everything may be for everybody, but we all need to question why we do things the way we do them. Lots of behaviours of ours that have an impact on the environment or on other people could be changed, and with many of them we would not even have to suffer from reduced comfort, I believe. Keep up the spirit!

[Patricia Mathews]

(19)

So I heat my clothing and keep the house cold. Next thing I know my ears and nose have turned red, my nose is dripping and running, and then they turn white. Frostbite time! Meanwhile my fingers have cracked and split and are now bleeding.

And working in electrically wired gloves? You would not be able to count the typos!

No, thank you.

[Kris De Decker]

(20)

Patricia, you should read the article on thermal underclothing, which explains the science of thermal comfort.

http://www.lowtechmagazine.com/2011/02/body-insulation-thermal-underwear.html

If you keep your body warm enough, your hands, ears and nose will be fine.

[Leo]

(21)

Low tech? Electricity is the worse way to heat.
IMHO oil heaters are betters, far bigger energy capacity... like zippo hand warmer.
You can put it where you want/need, 12 hours heating! why do not imagine a copper conduction repartition.

[johny]

(22)

The real test comes when getting naked to go to bed, taking a shower, eating in a cold environment then visiting the cold toilet. It would work great in a work setting where one has to work outdoors in -30 or less with extreme windchill factors.

[Earthling]

(23)

Kris, "If you keep your body warm enough, your hands, ears and nose will be fine."

That may depend on age, I'm 73, and my hands get cold when my body is toasty.

[BTidwell]

(24)

I suppose the key thing is how one defines comfort. Some people will put up with a lot that others might find uncomfortable because they have higher priorities, like "saving energy." During the several years I lived in the NE USA, I had to dress very warm for winters which hover around, if not considerably below, freezing for almost four months. Since I didn't tend to completely change clothes every time I came into my house,I found I could set the thermostat around 62f, rather than a usual 68f. Anything much cooler than that was noticeably chilly, which is unacceptable to me. I don't like air that feels cold, even if I'm not shivering. Anything below 55f made hard surfaces in the house cold to touch and made disrobing for bed or bath very uncomfortable. I will not lay in bed dreading having to get out of the warm covers in the morning as long as central heat is an option. I have to disagree that warm clothes make hats and gloves unnecessary. Any medical professional will tell you that those are key to avoiding hypothermia. You loose more heat from your head than any other body part, thus the reason for sleeping caps in days of old. At temps below 40f my fingers absolutely get cold and no amount of warm sweaters help.

[Whatever]

(25)

Roddy Pfeiffer > Heated clothes require an electric element close to the skin and subjects the wearer to unnecessary electromagnetic radiation.

What are *reliable sources* that would show that electromagnetic radiation causes health problems?

www.who.int/peh-emf/about/WhatisEMF/en/index1.html

[gareth]

(26)

Roddy Pfeiffer - very limited evidence for any reasonable amounts of electromagnetic radiation and harm, and many orders of magnitude less concern for DC than AC.

My electric innersoles use 5V DC and no more than 500mA each (USB battery), compared to the various unnamed chemicals in many cleaning products, ash fallout from coal power stations, with radiation, fire fighting foam residuals in our water etc etc - I think I am very comfortable with the risk of electric shoes and socks.

Just one point on tightly enclosed houses, in some areas (usually granite) this is a serious health concern due to the build up of Radon gas from the ground, leading to lung cancer. Locally, we have enforced standards of vents etc in houses in certain areas. Be careful.