The Five Biggest Myths About Saving Energy In The Summer

This summer is a hot one. With money tight and temperatures high, there's a temptation to test out unconventional ways to beat the the heat. But these odd home remedies can end up wasting energy and costing more money. Here's how to know what really works when you want to keep cool for cheap.

Myth: Cranking the air conditioner lower will make the house cool faster.

Usually not. Trane and Lennox make some nice variable speed air handlers, which can adjust their output to match demand. But most homes' units have just a single fan speed — on. As such, the house's temperature will always adjust at a fairly set rate. Cranking the thermostat to 15C to take a shortcut to 20C doesn't make a difference — the hot air moves at a set rate of speed. By undercutting the desired temperature, you're simply wasting an extra five degrees worth of energy and money.

Myth: Turn off the A/C while you're out.

If you're out all day with the A/C off, it takes a lot of work for a central A/C system to bring a hot house down to the desired temperature. Yet it's even more wasteful to keep it running for eight hours. The answer is to invest in a programmable thermostat, which can let the house warm through the day, then gradually lowering it to the right level before you return. Adjust the temperature up 10C while you're away, and a programmable thermostat can still save you up to 10 per cent on your annual heating bills. Reduce the demand on the system by closing curtains before you leave, to block the afternoon sun while you're gone.

Myth: Run ceiling fans to keep empty rooms cool.

Ceiling fans work by generating a wind chill effect, not by lowering a room's temperature. Essentially, they cool people, not rooms. That's not to say that fans aren't effective at lowering your cooling bills — in fact, using ceiling fans in conjunction with an A/C will allow you to comfortably raise the air conditioner's setting by several degrees. But, just like the lights, you should turn your ceiling fans off when you exit a room.

Myth: Closing vents on a central air system will boost efficiency.

This seems logical, but it can actually end up costing you a lot. Some sophisticated, super-efficient homes can effectively divide into zones of HVAC control. But most modern central air systems are balanced to distribute air throughout an entire house. So if you randomly close a register, the system keeps cooling and pumping without delivering the cool air to a usable space. You're basically paying to keep the inside of your A/C ducts frosty.

The compressor/condenser can cycle too frequently, putting additional strain on the system, leading to accelerated wear and tear. And for all the damage, it's not actually saving any energy. If you have a big house and you only want to keep a single room cool, consider a ductless mini-split air conditioner, or a basic window unit.

Myth: Air conditioning is the only way to keep cool.

We have it nice in Australia these days, but ubiquitous A/C is hardly the worldwide norm. People cope. And their strategies can come in handy. When managing editor Brian Barrett's A/C went out earlier this summer, he and his wife and dog hunkered down in a room under the house, a padded layer of carpet separating them from the cool concrete floor. A caveat from Barrett: "That only works if your basement's not too creepy."

Editor-in-Chief Joe Brown, on a trip to Zambia some years back, received a set of damp sheets as he checked into his evening's lodgings. "It's so hot, the water in the sheets evaporates," Brown says. "By the time you wake up, nothing is wet."

And features editor Harry Sawyers, as a kid at SEC college football games and on sweltering Georgia campouts, learned to grab a piece of ice from the cooler, wrap it in a rag, and move the melting cube from wrist to wrist. "Then you just wring the melted ice water out of the rag, right down your neck. It's country, but it works."

How do you optimise your system's performance — or beat the heat without A/C? Wipe the sweat off the keyboard and let us know.

[TXU - WKU - Consumerist - Horizon Services - SCE Home Energy Advisor - CUB Energy - DoE 1, 2, 3]

Picture: Robert Pernell/Shutterstock


Comments

    "Myth: Cranking the air conditioner lower will make the house cool faster."
    "But most homes’ units have just a single fan speed"
    Not sure whether he's talking about the 'air handler on an A/C or some other kind of dedicated 'air handling' system but most decent A/C's have variable fan speeds? We use reversible fans on hot days to suck the cold air up and circulate the air better for A/C use.

    Last edited 08/01/13 1:26 pm

      This particular section/myth has a couple of fallacies - 1. That A/C fans are single speed; from what I can tell is seems fairly standard for A/C systems to have variable speed fans (even old, crappy "hole in the wall" type ones...), and 2. That setting the A/C to 15°C when you want 20°C will use more power - not true, UNLESS you don't switch it off/change to 20°C once the room temp has hit 20°C.

      Rest of the article hits home though...

      But, "rate of speed"?? C'mon... :-p

      Probably it should have said that the Compressor has a fixed speed...

      Unless it is an inverter AC unit, the compressor is just thumping away at a fixed speed....

      Conventional AirConditioning units just use an AC (Alternating Current) running on 50Hz (Australia) Power.. The inverter units, use power electronics to rectify and then generate variable frequency AC, for the variable speed compressor motor....

      If you have such a unit, great, a higher temp will use less power....

      If you have a conventional reverse cycle AC unit, no matter what the temp setting is, the chiller will use the same power no matter the set temperature..... Just that for a higher temperature the compressor will cycle on and off more.... (Better to have a unit designed for a certain size house producing the right amount of cool air to keep it at a fixed temperature... However the ambient temp must also be designed for, meaning that it will only work most efficiently at one outside ambient temperature...

      Of course we have had variable speed fans in the AC units (and all fans) for a long time....

      All a higher fan speed does is blow the cool air further from the unit (or duct opening)

      I am happy for feedback...

    How to save energy - do NOT have an A/C system.

    Last century, unless you were very old, when it got hot most of us put up with it and went on about our lives.

      Yes, well this is the 21st century and airconditioning isn't that expensive if you use it correctly. Inverted machines have been around for years now and they are a major improvement on the older system.

        "Bugger carbon footprint, global warming... I'm a little bit uncomfortable that's much more important. I'm turning on a 7kW machine."

          Umm, I dunno about you but:

          1- I have a portable A/C that ONLY cools my room.
          2- A 7Kw Aircon unit DOESN'T USE 7Kw of power. My 4.4Kw portable uses 1800w.

          So, it only cools the room I need cool the most and it uses half the electricity compared to cooling power (it aso has a water reservoir for enhanced cooling using evaporative effect).

          Meanwhile, I don't use a dryer. I ALWAYS have my computer in sleep when I'm not using it and I don't continually leave my TV on.

          Tell me, how's my carbon footprint doing?....

          I'll stick with my A/C thanks, so I can sleep. You appear to be a bit grumpy....hot last night?...

          Why not be comfortable and why should you have to suffer?

          Just because it might make you feel nice and good inside thinking you are doing your bit for global warming - I don't need you trying to make people feel bad about being comfortable in their home.

          "I'm old and grumpy, and I want to talk down to people who don't have my same viewpoint'

      Also, I used to walk to school uphill, BOTH ways.

        In 50 degree heat. Through the snow. With no shoes.

        Last edited 09/01/13 1:05 pm

          You had no shoes! We had to wear shoes with spikes on the inside of them!

          And we lived in the middle of t' lake.

    You could also save energy by not setting your AC so ridiculously low. 20°C is pretty chilly, try setting the unit between 22 and 24 and it should still provide some excellent cooling.

      Always ticks me off that people set their aircon to 19 in summer, then when it gets to 19 in winter they set the heater to 26....

        Know what you mean, I'm 24deg summer and winter. Not to cold not to hot.

          mmm...just like warm porridge

            I like my house tepid. Like said why have 18 in summer and 30 in winter. Doesn't make sense, comfortable all year round and easier on the wallet suits me.

    Pro Tip from a Refrigeration Mechanic and Mechanical Engineer.

    It doesn't matter what you set your A/C unit on. The colder you set it, the more power it will use. There is no magical temperature. It wont cool any faster or any more efficiently any any particular set point.

    Comfort levels have more to do with humidity than temperature. The more humid it is, the cooler you'll want it to be.

    Pending on how long you're out for, you're probably best off leaving the unit on if it's less than a couple of hours. The energy required to bring the humidity back down will offset the savings you made by not running it. Instead put the set point up higher so it maintains humidity levels as the article suggested.

    Generally, my AC unit is in the fixed position....

    OFF

    Mid 30's are totally bearable, and in the evening where I live a cool breeze hits us and the temp goes down....

    In the day, if you feel hot inside, just go outside for a while, when you re enter the house it will feel refreshingly cool....

    Winters...

    Mid Coast NSW simply doesn't get cold...

    Stick a light jumper on and its fine.... who says we have to be able to wear a T-Shirt inside in winter... In Summer the same goes...

    Sure if it is extremely hot (V HIgh 30's or over 40), the AC unit is nice to have to make the place a bit more liveable.... But then working in an un-air-conditioned shed, you just get on with the work at-hand and drink a few litres of water...

    Hell, the Longer you have the AC on, the more power it uses.. the way to control hte power bill if that is what you are into, is to hit the off button.. (or on a 38 degree day, set it to 30 degrees, that is cool enough. For most activities.)

    Woozes the lot of ya... ("Back in My day," ok Old man...)

      That's great, if the house you live in has reasonable re-radiation characteristics. It was 28 degrees in my room last night, even when the cool change hit and dropped the outside temp to 19. And no matter how much I had my fan pushing the air in, the bricks of the house radiated ALOT more heat into my room than it was pushing out.

      That's why I have my portable A/C- only cools the room I'm in and is decently efficient too (evaporative tech built in).

      Don't get me wrong, I'd rather not use A/C and use my fan whenever possible instead. But anything above 22 in my room and I can't sleep properly. That's just me that temp, but everyone needs a lower temp at night to sleep. It's human physiology.

        Thanks Seven-T.

        Wow, can't sleep above 22 degrees, my wife says, don't go to Europe in summer then, you will have sleepless nights, as no-one has air conditioning 'in general' (They use hot water radiators in winter (and summer if it drops below 20 deg, lol) for heating, with no absorption chillers or compressor units.)

        In my house last night (timber clad), the outside temp didn't go below 30, ( inside was 33, the fan did a good job of making the air move) and when we wanted to use the AC to cool down a bit late at night found that it wasn't working (Blown up in a power surge 3 months ago and not checked... one more for the repair man..)

        Well the cool change has come here, the daytime temp today is a lot cooler than the night temp (with a hot westerly) last night..

        Last edited 06/11/15 2:13 pm

          Lol, yeah. I'd struggle in Hong Kong or Malaysia if they weren't absolute zealots over there on Aircon! Even to the extent it's too cold for me. I'm going again in 2 weeks and the outside temp kills me going from the hotel to work. Love the aircon in the MTR though....

          Ironically when I'm in Cairns, I'm fine, even with the massive humidity. I think I get really hot and bothered psychologically if I know I've got nowhere cool to go back to...

      ...why do you have an air conditioner, again?

        lol... good question...

        Several reasons, it Does get hot where I live (Over 40 Degrees), and It does stay hot at night (inside may still be 33 degrees at 3 am...)

        The AC unit was in my house when I bought it, so I hate to waste gadgets and throw them out....

        Lastly, we are all a bit woossy, if there is an easy way out...

        Oh, also, my wife works nights often, so having an AC to flick on in the heat of the day to cool and reduce inside humidity may help her sleep a bit better..... (Ok so I blame the woman..but she is European and doesn't really relish the hot weather like we Native Aussies do....)

        keep it light.

        Last edited 06/11/15 2:16 pm

          fair enough.

          Just moved into a place with fantastic non-aircon cooling. Fresh air vents, fantastic 98% of the time. Warm, rainy day? Not so much. How I wish there was an air con, just for those days. Seeing how we go this summer, and making a decision for next.

          Proper aspect, design, insulation etc goes a long way. We really shouldn't *rely* on AC, I fully agree there.

    Use a geothermal heatpump, much better than traditional AC in many ways. It is more efficient to exchange heat/cold through underground piping where the temperature is constant, unlike outdoor air exchanges which struggle to work in high temps. Plus they remove the unsightly boxes from the side of the house. Cost of running is less than having a second fridge for an entire home.

      Oh yeah, I'd LOVE to do that....but kind of not realistic for a renter...

      I'll be doing so for my own home though. I'm going to have an positive pressure home if I can afford to do it, with geothermal heatpump to make up the difference.

    It'd be pretty sweet to have an underground pool with a geothermal pump. Use the pool as a heatsink or something.

    I hate dragging things out, But obviously one of the best ways to reduce building temperature isn't actually insulation...

    It is stopping the sunlight from directly impacting the building, then the insulation doesn't have to deal with rejecting the 70 to 110 degree temperature of the direct sunlight....

    Shade curtains around sun facing walls, and even a suspended shadecloth roof covering/sail (I don't have this) would improve livability hugely, this will mean that the roof (ceiling) crawl space will never be warmer than ambient temperatures before the insulation starts working.... (obviously a suspended roof-concrete slab would also be good....

    Cheers\\\Enjoy the next couple of days....

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