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Keeping safe when using supplemental heat

Keeping safe when using supplemental heat

When the weather turns chilly, sometimes your main heat source doesn’t heat quickly or completely, or it’s expensive to run, and you may turn to supplemental heaters for a quick way to warm up.  Supplemental heating sources like radiators, space heaters, and fireplaces are alternative options to simply turning up the heat in your home or installing a new, main heating system.  However, they have limitations and safety considerations you should note!

Portable space heaters





  • Heats whole space, not limited to line-of-sight

  • Lightweight

  • Because it’s convection heat, it usually requires a fan to direct the heat

  • Can dry out the air excessively

  • Lose heat due to convection (heating air instead of objects)

  • May take longer to heat 

Infrared/ Quartz

  • Great for small, open spaces

  • Cost depends on which power source it uses: electric or gas (natural or propane).

  • Quickly heats due to direct transfer of radiant heat

  • More efficient than ceramic heaters (over 90% efficiency)

  • Must be in line-of-sight of the heater to feel warmth

  • Not good for large spaces

Oil-filled Radiator (electric)

  • Quiet!  Fans are not necessary in these models.  

  • Modern versions have features like programmable timers and adjustable thermostats. 

  • Radiant heat is very comfortable and continues even after the heater is turned off.

  • Surfaces become hot and may endanger children and pets.

  • These type of heaters may take longer to heat up a room initially.

  • They are heavy but most are equipped with casters for portability.


  • Kerosene stores well for long periods so it can be a good emergency heater for power outages.

  • Inexpensive

  • Quiet because no fans are needed

  • Can heat larger spaces like garages

  • Because it burns fuel liquid inside your home, you must take abundant safety precautions around flammable furnishings, children and pets.

  • Combustion byproducts mean that carbon monoxide monitors must ALWAYS be used, and room should be ventilated adequately (possibly losing heat).

  • They’re illegal to use indoors in MA and possibly other states

  • They produce water vapor, which can cause excess humidity

  • Kerosene can emit significant particulate pollutants, especially if burners/wicks are not kept clean

Sometimes the permanent heating system in your home is undersized and it can’t heat the whole home adequately.  In other cases, if you have a gas furnace, propane or natural gas can become relatively expensive!  In these cases, permanent supplemental heating (the installation of a heater in one part of the home) can help. 

Permanent Supplemental Heating




Electric Radiators or wall-mounted heaters

  • Provides steady heat with minimal safety issues

  • Unobtrusive because they are located on or near a wall

  • Can consume a lot of electricity during prolonged cold spells

Electric Heat Pump Mini-Split

  • Heat pumps are more efficient for larger spaces than portable electric heaters

  • Heater can be sized to the space very easily

  • Air handler portion is mounted on a wall, out of the way

  • Can be regulated with a programmable thermostat

  • Units typically heat and cool, making them very versatile

  • Long life

  • May also include an electric coil for emergency backup heating

  • More expensive initial investment than portable heaters

  • Requires exterior space for the heat pump

Wood heating systems

  • Wood burning fireplaces are attractive

  • Very economical if you have the ability to cut and haul wood

  • Fireplaces do not require power

  • Wood pellet stoves produce very little ash, burn cleanly and easy to operate

  • Long-lasting

  • Sealed fireplace inserts increase heat efficiency while decreasing emissions

  • Professional installation is recommended

  • Wood pellet stoves require electricity to operate the fan and feeder motor

  • Flues must be cleaned at least annually to prevent fire risk

  • Carbon monoxide monitors must ALWAYS be used and it’s a good idea to monitor for CO2 and NOx

  • Unsealed fireplaces always have risks of dangerous smoke and embers coming out of the firebox into your living space


Gas Fireplace or heater

  • Gas fireplaces are attractive and vented models are readily available

  • Can work when the power is off but are more efficient when using the fan to disperse heat

  • Environmentally friendly

  • Professional installation is recommended for any permanent combustion heater

  • Requires a nearby gas line

  • Carbon monoxide monitors must ALWAYS be used and it’s a good idea to monitor for CO2 and NOx


Propane or Natural Gas Heater

  • Very efficient and inexpensive

  • Available with safety features such as oxygen depletion sensor (ODS) that immediately shuts down the blue flame heater if carbon monoxide or lack of oxygen is detected

  • Can work when power is off but are more efficient when using the fan to disperse heat

  • Broad choice of unvented models; however read the precautions below

  • Professional installation is recommended for any permanent combustion heater

  • Requires a nearby gas line

  • Lack of venting required does not mean lack of air pollution.  NO2 and CO2 levels can become relatively high if ventilation is not used.

  • Combustion byproducts mean that carbon monoxide monitors must ALWAYS be used, and room should be ventilated adequately (possibly losing heat)

  • Should not be left burning when the room is unattended

We want you to be knowledgeable about and avoid air quality poisons that are created just by heating your home with a combustion unit!  According to a Japanese study of propane, kerosene and electric space heaters used in a non-ventilated, 215 ft2 room:

  • concentrations of NO2 and CO2 from all the heaters except the electric heater exceeded the 1-hr Environmental Quality Standards (NO2: 0.04-0.06 ppm) and the Building Sanitation Management Standards (BSMS, CO2: 1,000 ppm).  

  • The CO concentration emitted from reflection kerosene and natural gas heaters slightly exceeded the BSMS (10 ppm). 

  • The concentrations of suspended particulate matter and polynuclear aromatic hydrocarbons showed an increasing tendency during the use of kerosene-fueled heaters. 

In a study of kerosene heaters, NOx, CO2 and CO are the main gaseous pollutants emitted by kerosene space heaters. In addition, carbonyl compounds (formaldehyde, acetaldehyde, acetone) were identified, as well as ∼50 other VOCs, six of which presenting a risk for human health (1,3-butadiene, benzene, ethylene, propene, isobutene and acetylene). There is an accumulation of soot on wick heaters after a few hours of operation, which causes incomplete combustion that increases CO emissions, (CO poisonings are frequent with kerosene heater use). Therefore, the recommendation with any combustion gas heater is to ventilate profusely, or go with a vented heater model.  This article on BuildingGreen.com concurs that we should avoid unvented gas heaters. 

Photo by Jessica Johnston on Unsplash

Will a Radiant Barrier Help My Home’s Air Quality?

Will a Radiant Barrier Help My Home’s Air Quality?

Radiant barriers have been a “hot” topic for the last few years: If to install them, where to install them, and how to install them.  Are they worth the work and cost?  It’s time well-spent to do some research before diving in with such a project.

Radiation is one of the three types of heat transfer, along with convection and conduction.  A radiant barrier is a material with a shiny surface that reflects radiant heat back outside the home.  If the barrier gets dusty or is installed incorrectly, however, it does not work well. 

According to Attainablehome.com (a builder’s website devoted to building of modern, sustainable, and high quality homes that is within reach of household incomes), properly installed radiant barriers can reduce heating costs in the hottest months in southern climates, if the home’s air conditioning system is located in the attic. It can also offer a degree of protection to that equipment when the barrier is installed over the equipment, “shielding” it. 

In colder climates, however, radiant barriers are not recommended for several reasons.

  • The savings in reflecting heat away from the home in summer is minimal.

  • Cold climates can allow moisture to condense behind the barrier, creating mold issues.  Perforated radiant barriers can reduce this problem, though.

What is “properly installed”?  Here is a good video showing installation of a radiant barrier over a garage.  Radiant barriers:

  • Need an air gap: don’t install the barrier sandwiched between existing insulation, as it can conduct heat into it.  For instance, do not install radiant barrier foam board (such as LP’s Techshield) and sprayfoam over it. (energyvanguard.com)

  • Need to be relatively clean: dust will reduce the effectiveness of the barrier, so installing on the attic floor is not recommended in most cases. 

  • Must be the right type for your home/climate. There are:

    • Perforated and non-perforated: Perforated barriers allow vapors to escape through the barrier, reducing the chance that moisture or mold will build up behind it.   If you live in a hot, humid climate and have a vented attic, a highly permeable barrier like “Super-Perf” from AtticFoil is recommended to allow moisture to pass through. 

    • Made with insulation or board attached to the radiant surface

  • Must not block air flow in the attic.  Most vented attics have soffit and ridge vents, so do not block the air flow between these two, or moisture issues may result.

In a 2010 article that still applies today, energy advisor Martin Holladay stated there are 5 factors that determine whether a radiant barrier is a good option for your home (discussed in this video):

  • Do you live in a hot climate?  Yes = consider radiant barrier.

  • Do you live in a humid climate?  Yes = the radiant barrier must be carefully and correctly installed so that moisture problems are not created.

  • Do you have a one-story home?  One story homes tend to have larger roofs to cover the livable square feet, so a radiant barrier in a one-story home will be more effective than a two-story home of comparable square feet.

  • Do you have air ducts in your attic?  Yes = consider radiant barrier to shield them.

  • Is the air barrier installed correctly?  This is imperative, so the barrier has to be compatible with the insulation in your attic.

In times of low-cost energy, installing a radiant barrier may not be worth it. (energyvanguard.com)  For example, in Houston in 2011 (a hot climate in a year with similar kilowatt-hour (kwh) energy cost to today), a homeowner could save about 180 kwh per year with a radiant barrier installed on their 2000 sf newbuild home, considering that it is installed under the roof decking and the only additional cost was the more expensive barrier under the decking ($200).  This is about $25 per year savings, which would be an 8 year payback if there is no mortgage, or only about 50 cents per month if there is a mortgage (check the article for the explanation!)  It’s not a whole lot, but if energy prices go up (they will at some point), the savings could be more.

According to this video, LP Techshield (an OSB board with aluminum coating on one side) produced an 18 degree reduction in temperature in a doghouse.  Another video using the same product achieved an 8-10 degree reduction in a real house. 

So, how does all of this affect your air quality?  At HypoAir, we are in favor of not adding things that harm you or your home, so adding a radiant barrier to an existing home must be carefully considered.  Here are some steps to check whether it is right for you: 

  • If you have an unvented attic, a radiant barrier is likely not to benefit you.  If you have a vented attic, make sure the vents are not blocked and there is sufficient insulation in the walls/floors of the attic facing the conditioned space. 

  • Consider the current state of your attic and take temperature and humidity measurements in the attic and in the home as a “baseline”.  

  • If possible, you could conduct a small “experiment” in a part of your attic that faces the sun by installing one roll only (best if it shields some ductwork) and seeing how it affects attic and home temperature and humidity.  

  • If this test is favorable, continue with installation of the rest of the south- or west-facing sides.  Although I could not find much information about it, radiant heat is not very applicable on the north-or east-facing walls in the northern hemisphere. 

  • If humidity increases with the test spot under similar atmospheric conditions, it’s best to terminate the experiment and remove the barrier. 

Radiant barrier material is not very expensive, so if you can install it yourself, it can provide energy savings going forward.   It’s best to take your time and research the pros and cons of installing it in your home and not succumb to pressure from a salesperson, however.  Overall, it should not increase your energy use or humidity levels, so make sure to hold the manufacturer and/or installer to their claims.  We’d love to hear from you on how radiant barrier affects your home’s atmosphere!

Photo by Greg Rosenke on Unsplash