Lessening the Environmental Impact of Outdoor Heaters

Lessening the Environmental Impact of Outdoor Heaters

Posted by Eric Kahn on Oct 28th 2022

If you’re shopping for outdoor heaters you may have some concern about their effect on the planet. Patio heaters heat the outdoors, consequently there is an environmental impact from using them. But how significant is the impact, what methods of outdoor heating have the most and least environmental effect, and how does patio heating compare with the carbon footprint of other frequent American consumer activities?

How Detrimental are Patio Heaters to the Environment?

Electric Vs. Natural Gas Patio Heaters

There is a great deal of misinformation on the web about the topic of electric vs. gas infrared patio heaters. Numerous websites state that gas patio heaters heat the air while electric patio heaters are infrared. That is false. The truth is that all patio heaters operate on infrared radiant technology. One could argue that less heat escapes electric patio heaters and therefore they are more efficient. That is generally true on a local level. But it does not take into account the inefficiency of production, transmission, and distribution of electricity. Roughly ⅓ of the energy value of the raw materials that go into making electricity are not converted into electricity. There are additional transmission and distribution losses.

Another important factor when considering electric patio heaters and the environment is how and where the electricity was generated. If the electricity is generated from renewable resources, like solar panels, which were manufactured with sustainable practices, and have a recycling program for their end of life, then electric-powered patio heaters may be the most environmentally-friendly option. However, nationally we purchase electricity from a grid with various sources generating the electricity. An enormous factor in electric patio heaters’ efficiency is model selection and efficient placement for the ambient conditions. Alfresco Heating helps you with that.

Gas patio heaters with ceramic tile burners — typical of overhead gas patio heaters — are more efficient than gas patio heaters with metal heat emitters, typical of mushroom-shaped standing heaters. The least efficient gas outside heaters are the ones with the glass flame tube in the middle. The yellow flame is not clean burning and the glass acts as an insulator. Worst, environmentally, of all gas outdoor “heaters” are fire tables and fire pits. However, even those are less negatively impactful on the environment than outdoor wood fires.

Natural gas burns clean. Liquid propane (LP) heaters are somewhat finicky and not easy to tune optimally. Therefore, they may be a less clean-burning option. However, portable propane patio heaters are convenient. (Propane patio heaters can be moved around, and typically just need assembly - an hour or two of labor - while natural gas or electric heaters require infrastructure - typically a day or two of labor.)

I sometimes see propane “mushroom” patio heaters turned down onto low flame settings, and when the flame settings are low I see the yellow tips on the flames grow larger while the blue part of the flame is reduced. This indicates the flames are burning dirty, and producing carbon monoxide. (Common sense: CO is worse for the environment than CO₂.) When a customer does this frequently it leads to carbon build up inside the emitter grid (the metal mesh that glows orange) and on the burner, which in turn causes lower efficiency, and this becomes a downward spiral. I suggest that you try to avoid running your patio heaters on low if the flames turn yellow.

As with electric patio heaters, a huge factor in gas patio heaters’ efficiency is model selection and efficient placement for the ambient conditions. Alfresco Heating helps you with that.

Patio Heaters Vs. Gas Fire Tables

Gas fire tables and gas fire pits attract people with dancing yellow flames. But yellow flame indicates incomplete combustion from an oxygen shortage. While a blue flame, or a glowing orange ceramic-tile burner or metal heat emitter, does create CO2 along with heat, a gas fire table, with a yellow flame, designed for visual aesthetics more than heating, has less oxygen in the mix, and consequently produces more carbon monoxide than a patio heater. Furthermore gas fire pits are far less efficient as heaters than patio heaters are. A 40,000 BTU gas fire table provides little heat while a 40,000 BTU gas patio heater provides a significant amount of heat.

Patio Heaters Vs. Wood-Burning Fires

Smoke harms air quality and public health. Wood-burning fire pits emit carbon dioxide (CO₂), carbon monoxide (CO), and dust particles. Common sense shows us that any patio heaters burn far cleaner than wood fires.

Facts on Environmental Impact

According to the Environmental Protection Agency (EPA), combustion from one standard 5-gallon propane tank with 18 lbs. of propane emits .024 metric tons of carbon dioxide, which is equivalent to driving almost 60 miles, burning over 26 pounds of coal, or charging your smartphone 2,919 times. Therefore, the CO₂ generated by driving one hour at 60 MPH is equivalent to running a 40,000 BTU propane patio heater for more than 9.5 hours.

Electric patio heaters. The USA average of CO₂ generated per MWH (=1,000 KWH) of electricity is 818.3 lbs. Therefore one 6,000 watt electric heater creates an average of slightly less than five lbs of CO₂ per hour, plus line losses.

Natural gas patio heaters. Natural gas releases 0.0053 metric tons = 11.69 lbs. of CO₂/therm. A therm contains roughly 100,000 BTUs. A 50,000 BTU post heater CO₂output is slightly less than six lbs/hour. One typical overhead gas patio heater uses 34,000 BTU per hour. CO₂ output is slightly less than four lbs/hour.

Propane portable outdoor heaters. 0.024 metric tons of CO₂= 52.91 lbs. per 18 pounds of propane (in a full standard propane tank). It follows that one 40,000 BTU propane patio heater’s CO₂output is slightly less than 5½ lbs. per hour.

Conclusion: Permanent overhead natural gas patio heaters produce less CO₂ than portable propane patio heaters or electric patio heaters with equivalent output, based on national averages. However, one also may want to consider the source of the fuel.

Quality Outdoor Heaters Vs. Those From Big Box Stores

Patio heaters from big box stores typically have less strict quality control and are made of materials that are not as durable compared to higher-quality outdoor heaters. Some economy patio heaters aren’t supported with replacement parts. They are often flimsy, and are made to be disposable, adding to the landfill. Patio heaters sold by Alfresco Heating have parts that can be replaced, and are vetted to be of sufficient quality that the lifespan of each heater is longer.

Most inexpensive economy patio heaters have flimsy three-part reflectors, which very quickly twist and disfigure. The reflection of radiant heat is thereby reduced. So if you buy a portable patio heater, please invest in one with a one-piece reflector. The burner and head design of cheap patio heaters typically have big air vents and large perforations in thin metal emitters, leading them to be less efficient than their more-expensive cousins.

Buying “cheap” patio heaters manufactured from overseas increases environmental impact three ways:

  1. There is an increased carbon footprint from shipping them on container ships.
  2. Many of them are packaged with excessive amounts of open-cell foam in their boxes.
  3. Fuel efficiency is compromised by thin emitter grids and twisty reflectors.
  4. They end up in the landfill sooner, and more often, than good quality outdoor heaters.

Patio heaters have minimal environmental impact when:

  • They are only on for 20 minutes of preheating and during the use of an area. They are off a vast majority of the time.
  • Efficient patio heaters are selected.
  • The right patio heaters for the local conditions are selected.
  • Placement of the patio heaters is optimized.

How to minimize the environmental impact of patio heating:

  • Turn them off when you are done using them.
  • Install timers on permanent patio heaters so that they can’t be left on accidentally.
  • Choose well made patio heaters that will have a long life span.
  • Consult with an expert to select outdoor heaters that are optimal for your ambient conditions.
  • Consult with an expert to lay-out effective and efficient locations of outside heaters for a permanent installation.
  • avoid running your upright patio heaters on low if the flames turn yellow.
  • Drive less.

Future Patio Heater Efficiency

Future patio heaters can be factory-made more efficiently. Manufacturers just need to be reminded of two things: 

  1. The environmental impact of their products matter.
  2. There is an increasing demand for environmentally-prudent items. 

Make higher-efficiency patio heaters and back their efficiency up with testing, and a bit of marketing; and then the investment in engineering, prototyping, getting CSA or UL (or equivalent) approval, and going into production will pay off very well. Therefore I don’t think carbon-footprint regulations for patio heaters will be necessary or even helpful.

How To Manufacture Patio Heaters That are More Efficient

Current omni-directional mushroom heaters have basic, blue-flame, burners. Perhaps a high-efficiency, pressurized ceramic burner can be devised, similar to those used on high-intensity overhead gas patio heaters, only cylindrical. Wind resistance could be improved. Different placements, shapes, and sizes of top reflectors could be tested to improve heat spread. Double wall, insulated reflectors could be used and the reflective surfaces of them could be polished.

Overhead patio heaters could also become more efficient. Burner efficiency might be improved by better engineered reflectors. Fuel efficiency can be improved through upgraded burner design. Heat loss can be reduced by insulation and double walls.

Note to patio heater manufacturers: Please do contact me to brainstorm on how to improve your brand’s patio heaters’ energy efficiency. I am not an engineer, however I have worked with patio heaters for over 25 years. I do have some good ideas, some “know how,” and some “can do.”

Overall Environmental Impact of Patio Heaters Vs. Other Normal Activities

No matter the type of outdoor heaters you choose to use, they have minimal impact on the environment, compared to routine activities like driving your gas-powered car, flying in a jet, or heating your house 24/7. Patio heaters are generally only on for short periods of time, when the patio is occupied. While patio heaters are a conspicuous target for groups with concerns about our global environment, a person can make an appreciably greater reduction to their carbon footprint by slightly reducing their regular activities. Selling a product line that contributes (in a diminutive way) to global warming does not make us anti-environmentalists any more than driving a car makes you so. At Alfresco Heating we do care about the environment. And we care about keeping you cozy and warm so that you can enjoy dining and socializing alfresco.

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