How Can I Reduce My Heating Bill?

Posted on June 9, 2022 by T.D. Inoue

If you’ve read my posts before, you know I’ve had mixed feelings about heat pumps. On the one hand, they’re great. On the other, historically, natural gas, and even heating oil, have provided heat for your home cheaper than the electricity based heat pump. But, for many reasons, especially environmental ones, my preference is to use heat pumps for primary heating and cooling.

Fossil fuels are a dead end

This last year, we’ve seen historic price increases in fossil fuels that have hit almost every household. Heating oil, natural gas and propane bills shot up, often doubling your heating bills. On top of that, automotive gas prices increased like crazy. These price spikes inflated the prices of just about everything – from fertilizer to vegetables. From avocados to sneakers. Fossil fuel prices affect almost everything.

Now is the time to add a heat pump

If you have central air conditioning, you can probably switch to a heat pump without too much difficulty.

An air conditioner and a heat pump are virtually identical. The difference is, a heat pump has an extra valve that allows the indoor air to blow cold or hot. You might have noticed that the outdoor air conditioner blows out hot air when it runs. A heat pump just switches it so that the hot air blows indoors instead of outdoors. When the air blows hot inside, the cold air blows outside. It’s the way these refrigerant based systems work. One side is hot and the other side is cold.

The great thing about heat pumps is they can be really efficient. Modern heat pumps give you three to four times as much heat out as the electrical power you put in. Think of a hair dryer. That’s considered almost 100% efficient because it converts those 1,500 electric Watts into an equivalent amount of heat. A heat pump, seemingly miraculously, can take the 1,500 Watts and convert it into the equivalent of 5,000 Watts of heat.

If you replace your air conditioner with a properly sized heat pump, you can heat your home super efficiently for most of the year without burning a drop of fossil fuels at home. You can do a heat pump retrofit if you have an existing furnace that burns oil, propane or natural gas and uses the same air handling system for air conditioning. You can continue using the furnace for the coldest parts of winter or when you need to warm your house quickly.

How much money will I save by using a heat pump?

There are a lot of details that go into answering this question. The first is: “how much does electricity cost per kilo-Watt-hour?” and “how much does my gas/oil/propane cost per gallon?”

It does get more complicated. Your local climate makes a huge difference. For example, if you live in a place where the winters are relatively mild, you can probably heat your home all year with just the heat pump and use no fossil fuels. In fact, if you live in a place like that, fossil fuel furnaces are probably relatively rare. In that climate, heat pumps are mostly a “no-brainer.”

Where it becomes trickier is where the winters are long and cold. Heat pumps will work but may struggle when it gets much colder out. In fact, the heat pump is most efficient when it’s only “cool”, like 45 degrees, F. As the temperature drops, the heat pump loses efficiency and also puts out less heat. This is exactly the opposite of what you need! But that’s the physics of it. So if you live in a climate where it’s below freezing for long periods of time, the heat pump might not be the best alternative. However, even then, a heat pump can reduce your utility bills.

During the Spring and Fall, we often start using our heating systems to take the edge off. Maybe it’s 45-60 degrees out. With a heat pump working in its optimal range, you can heat your home without using any fossil fuel. This might reduce your gas/oil/propane bills by 50% or more. Again, it depends on the cost of electricity versus the cost of your fuel.

Let’s run a few examples. Currently, home heating oil is up to about $5/gallon. That’s crazy high, so I won’t use that for comparison. Instead, I’ll use $3.20/gallon, which is about what it cost in PA during the winter of 2021/2022. Electricity here cost about $0.15/kWh when you factor in the generation and transmission costs. Some places are much cheaper, some much more expensive, so you need to adjust for your own utility costs.

At these costs, assuming typical efficiencies for furnaces and heat pumps, it would cost about half as much to heat with a heat pump, during mild weather, than using heating oil. As the temperature drops, the savings will be less, but still substantial. So, at these electricity and fuel costs, I’d say a heat pump falls into that “no-brainer” category. Every year you keep your AC and only run the oil furnace, you’re losing money. If you’re going to be in your home for more than a few more years, you could pay off the heat pump with the savings. Again, there are many factors, so you have to run your own numbers for comparison.

Now, consider what happens if oil stays at $5/gallon or goes higher for next winter. At that price, you would spend one third as much (!) on heating with a heat pump compared with oil. If you use 750 gallons of oil, the oil would cost $3,750. The electricity for the heat pump would cost only $1,250, saving you $2,500. Who knows what prices will do?

You also have to consider the “incremental costs” of upgrading to a heat pump. Suppose your air conditioner is old and you’re thinking about replacing it. It’s probably inefficient. If you replaced it with a modern heat pump, it would be cheaper for air conditioning AND you’d save money using it for heating. Since you would need to replace the AC anyway, the additional cost of the heat pump compared to a new AC unit might be small so the combination of cost savings on air conditioning and heating could pay off the additional purchase cost very quickly.

Cost comparisons for natural gas are similar. Gas prices fluctuated wildly this winter and people saw their costs double. Gas prices have since dropped a lot, but there’s no telling what will happen in the future.

I’d be remiss not to mention the price fluctuations in electricity. My own electricity costs increased about 10% this year. Others in Pennsylvania saw their electric costs double. This happened all over the country, so again, you have to do your own comparisons.

Other advantages and conclusions

There are other advantages to using a heat pump. How often do you maintain your air conditioner? Most people only call their HVAC company when they have problems. On the other hand, when you have a combustion system, you should really get it cleaned and checked at least once a year.

Safety is another important consideration. A heat pump doesn’t burn fuel, so there’s no chance of carbon monoxide poisoning. Sadly, while rare, fossil fuel systems are responsible for about 430 carbon monoxide related deaths each year, according to the CDC. They also say that about 50,000 people are hospitalized each year from accidental carbon monoxide poisoning.

If you have propane or heating oil, you have to store fuel in tanks on your property. Heat pumps use the same electricity that powers your home. No need for storage, so you never need to worry about “filling up the tanks.” Convenience with heat pumps is a big benefit.

All things considered, if you live in a mild or moderate climate, a heat pump might be a great upgrade for your air conditioning system. You can save money on your summer air conditioning and winter heating while avoiding the inconvenience and potential dangers of a fossil fuel burning system. You might even get a rebate from your electric company, as many want you to use heat pumps instead of burning fossil fuels.

Is Geothermal Worth It?

Posted on September 8, 2019 by T.D. Inoue

On paper, geothermal, or more accurately, Ground Source Heat Pumps (GSHP), are amazing. They pump out endless heat during the winter and cold during the summer at costs that are often much lower than conventional heat pumps. They don’t pollute (directly). They’re quiet, comfortable and, when properly maintained, should last decades.

But what’s the reality? Are geothermal heat pumps really worth it? Keep reading to learn the answers!

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Insulating Attics and Cathedral Ceilings

Posted on December 21, 2016 by T.D. Inoue

In the first article of this series, I discussed a lot of the theory behind attic insulation that you should know before taking on your insulation project. If you haven’t read it, please, click the link and do your best to understand the basics before proceeding.

Condensation – killing houses slowly but surely

This house definitely has problems

This winter, most of the questions I’ve received have been about moisture buildup in attics or cathedral ceilings. And all have the same answer – humid air from the house is rising up through all the little cracks and holes in your ceiling. Once it gets into the attic space (or the space between the roof and the ceiling of a cathedral ceiling), the air cools rapidly and the water held in the air condenses on to a near-by cold surface – usually the underside of the roof or the roofing nails.

Once this happens, the water drips into your insulation or soaks into the roof sheathing. If this happens once and dries out, it’s no big problem. But during the course of the winter, this happens again and again, and before you know it, it’s raining inside the house as water leaks through holes in the ceiling.

There’s a saying – “there’s no such thing as a small water problem.” But often people will try to put a band-aid on them. Unfortunately, every day a water problem is neglected, is another day closer to serious structural problems and tens of thousands of dollars of repairs. So it is in your best interest to deal with water problems as seriously as if your house was on fire. Deal with it today, or you’ll be really sorry tomorrow.

What a moisture problem looks like

Let’s look at the underside of a roof that has experience this repeated wetting from condensation:

Insulation against roof deck leads to roof failure

Fiberglass insulation against roof deck in an attic leads to roof failure

Moldy roof deck above a cathedral ceiling

The first thing knowledgeable people ask is: “will adding more ventilation eliminate the problem?”

We’ve all been told that you have to have air flowing through the channels, from the eaves (soffit vents) up to the peak (ridge vent) in order to flush out the moisture. But this is only part of the story and it doesn’t guarantee anything. In some cases, it makes the problems worse.

The purpose of insulation in winter is to slow the heat loss from the house and out the roof. Take a look at the photo at the top of this article. Half the roof has snow, the other half does not. The half where the snow has melted is a clear sign of heat loss from the house. The heat warms the roof sheathing and melts the snow.

Recall what you know about condensation – condensation occurs when moisture in the air comes in contact with a cold surface. The roof is above the insulation, so it’s supposed to be cold. If it were warm (like the right half of the photo of snow), then condensation would be less likely. The situation is a Catch-22 – good insulation equals cold roof. Cold roof plus humid air equals condensation. Ugh!

Given these conflicting issues, what do you do?

Preventing moisture problems in attics and cathedral ceilings

U.S. EPA Air infiltration poster

The answer is simple – reduce the amount of humid air that can come in contact with the cold roof.

In the winter, almost all the moisture comes from inside the house. It rises up, along with the warm air, finds every tiny crack in the ceiling, and gets up into the attic or inside the cavity under a cathedral ceiling.

Step 1: reduce moisture in the house

The first thing you want to do is reduce the amount of water getting into the air from inside the house.

Ventilate when showering

The most common source of large amounts of moisture is the shower. When you shower, you create a “worst case” scenario – hot water saturates the air. That “super saturated” air will immediately dump the humidity onto any cooler surface it touches.

When you shower, you must run the bath fan during and after your shower until the all the excess moisture in the bathroom is flushed out. Usually, this means allowing the bath fan to run for approximately 30 minutes after you shower.

If you have a door on the bathroom, keep it closed until all the moisture is flushed out. Never shower with the bathroom door open because the moisture will flow out into other areas of the house that are not designed to eliminate the moisture.

Bath fan tips:

Ensure the fan actually works. Put a piece of paper under the fan. It should suck strongly to the fan’s intake. If it does not, then the fan may be improperly vented.
Check the fan installation. Pull down the grill under the fan and look for gaps between the ceiling and the fan. Use canned foam to seal these gaps.
Make sure the fan vents through the roof. Venting the fan into the attic is common and exceedly stupid as it virtually guarantees a rotten roof. The duct from the fan should be as short as possible and go straight up through the roof. Your fan is worthless if the duct runs 50 feet across the the attic then lays on the soffit.
Install a humidistat that automatically runs the fan based on humidity levels. There are even bath fans with humidistats built in now but I prefer separate switches with humidistats like the one linked to above or this one. Why? Because you are less likely to forget to turn it on. The humidistat is wired in parallel with the normal switch so either one can activate the fan.

Ensure the dryer vents outside

Far too often, dryer vents take long paths to get outside. This leads to inefficient or even dangerous operation. If your dryer takes forever to dry clothes, chances are good that it’s not venting effectively.

Don’t even think about getting a dryer “heat reclamation” device. These pump gallons of humid hot air into your home, greatly increasing your odds of mold and roof rot.

Turn off humidifiers

If you have moisture problems and you use a humidifier, stop using the humidifier. Humidifiers can dump gallons of water into the air every day. Central humidifiers are especially bad because they use the homes leaky ductwork to spread the moisture.

If you absolutely must use a humidifier, use it only in the room where you sleep and turn it off when you’re not using it.

Keep in mind that the primary reason you need a humidifier is because your house is leaking in cold, dry air. The need for a humidifier is a clear sign that your house is inefficient and you could save a lot of money and be much more comfortable by tightening your home. I know – when I moved into my home, our lips and skin cracked, our noses bled and we were really uncomfortable. We had to use humidifier round the clock to be comfortable. After replacing our old windows and air sealing the house, we haven’t had to use the humidifiers once.

Ventilate when cooking

If you cook on the stove a lot, make sure you use an outdoor venting range hood. This is especially important if you have a gas stove or oven because these generate carbon monoxide and water vapor.

Conservatively water plants

Much of that water you use to water plants ends up inside the house.

Avoid “ventless” gas fireplaces

These should be outlawed. Ventless gas fireplaces generate tons of water vapor and, if not running cleanly, carbon monoxide, which can kill you. No matter what Bob Villa might say, these units should never be installed or used. It’s physics. A byproduct of combustion is water and carbon dioxide. And if the combustion isn’t *perfect*, you also get carbon monoxide.

Look for hidden water sources

Basements and crawlspaces

If you have a crawl space or damp basement, this could lead to huge amounts of moisture entering your home. Many articles have been written on this topic. For now, be aware of this and check your basement and deal with any moisture problems under the house. If you don’t there’s a good chance you’ll end up with attic/roof moisture problems.

Indoor ponds and fountains

Self explanatory.

Any other place water is used in the house

Step 2: Air seal the ceiling between the living space and the insulated attic/cathedral ceiling

I’ll save myself 1000 words – refer to this excellent diagram and ensure that your home has an airtight seal between the living space and the attic or the inside of your cathedral ceiling.

Avoid traditional recessed light fixtures!

If you’re considering (or already have) recessed light fixtures, use air tight LED fixtures. The manufacturers completely lie when they label traditional fixtures as ICAT (insulation contact, air tight). I dare you – turn one of these fixtures upside down and fill them with water. Water will rush through all the holes in the fixture. Now picture your ceiling during the winter – air flows right through the fixture, carrying moisture up into your attic or ceiling. You are virtually guaranteed roof rot if you have a ceiling filled with recessed lights.

Don’t believe me? remember this photo from earlier? This builder swore up and down that he did everything right and the roof was still rotting. Why? Because he installed about 20 of these fixtures in the ceiling. You can’t argue with physics.

Fortunately, you can cut your energy usage in quarter, never have to change a bulb again, and eliminate the moisture infiltration problem by using flush-mount LED lights like these. You can also retrofit existing recessed light fixtures using these types of lights.

One word of advice – use a thin bead of caulk around the lip of the fixture to seal it to your ceiling. This is the only way to ensure an air-tight seal. Yes, it will be a pain in the butt to remove later, but these things are rated to last 36,000 hours. That’s 4-years of continuous use so 10-20 years in real use. LEDs often last much longer.

Seal all duct registers and especially bath fans

I have never seen a bath fan that’s properly air sealed, and they’re in the most critical location in the house. The installer will cut a hole about 1″ larger than the fan then cover up this big gap with the fan’s grill. Out of sight, out of mind.

All that humid air from your showers will go right up through these gaps and into your attic. This is the place you should start with your air sealing because it’s so easy and so effective.

After that, if you have heating/air conditioning vents in the ceiling between the living space and attic, remove the grills (called “registers” in industry lingo for some reason). These are installed the same way as bath fans. Big holes. Sloppy installation. You can use spray foam or caulk to seal the gaps. Or, use this incredible tape, called “foil mastic.” Clean off the sheet metal of the duct “boot” (that’s the metal thing the duct is attached to that screws to your ceiling). And use this tape to seal all around the perimeter where the boot attaches to the ceiling. Be careful to measure it so that it doesn’t show outside the register before sticking it to the ceiling because once it sticks, it’s on there for good!

Cover the attic hatch

Attic hatches are responsible for a huge amount of energy loss and the associated moisture damage in attics. Make sure yours is air-tight (which is almost none except for these Rainbow attic stairs). These are the best I’ve ever seen and worth the money.

For the other 99% of you who already have attic stairs, install the ESS Energy attic stair hatch. This thing is awesome. Or, you can build your own out of foam-board. But seriously, the ESS Energy system is so much better than the other solutions out there that’s it’s worth it.

Get a blower door test before and after air sealing

The best way to go about air sealing is to have an energy auditor come and do an infrared inspection with blower door test before and after the project. You do it before the air sealing to locate the air leaks so you can prioritize the work. You do it after to ensure the work was done right!

When I did these inspections on a daily basis, I found that the combination of blower door test and infrared thermography was the only reliable way of finding the problems. Some folks will say they can find all the problems without the right tools, but, frankly, they’re misguided. I don’t care if you’ve been doing this for 50 years, your eyes are not going to find hidden problems.

Let me give you an example. Suppose you go to the doctor. You’re not feeling well. Strange pains in your abdomen. If the doctor prodded you a couple times, told you “it’s nothing, you’ve got gas” then said “I don’t need to use a newfangled MRI machine” – would you trust your life to them?

For a few hundred bucks, are you going to trust someone’s eyes or a proven tool?

Ready? Insulate your attic!

After you’ve reduced humidity problems in your home, then air-sealed the ceiling between the living space and the attic/cathedral ceiling, then you can insulate.

How should you insulate? Honestly, if you’ve done your prep work properly, you can use cellulose, spray foam, fiberglass, recycled denim or horse hair and your home will be relatively well insulated and energy efficient.

Obviously there are differences, but it should be clear that the prep work for insulation is key. Even the best insulation product can have issues if you don’t air seal and reduce humidity.

Some guidelines for insulation in colder climates

I have to start by saying this is all for winter insulation. Hot, humid climates have their own rules which are often reversed from cold climates.

Moisture barriers go towards the warm, inside of the house

In winter, the moisture barrier should be the first thing beyond the ceiling material. You absolutely don’t want to trap moisture on the cold side of the insulation.

Refer to your local building code for the use of moisture barriers. Many jurisdictions are changing their approach to moisture barriers.

Install insulation

Like I said, the specific insulation product usually doesn’t matter if everything to this point has been done right. The main differences between products are price, R-value per inch of thickness and convenience of use. These can be significant differences and you have to determine what works best for your own home.

Some things they should tell you about insulation but often don’t

Blown in products are messy. Cellulose or fiberglass blown in to an attic basically renders the attic useless for other purposes. If you think you’ll never go into the attic, then great, blow in a couple feet of cellulose and be done with it. But if you have heating/cooling equipment up there or you want to use the storage space, you will hate the decision. Trust me. I want to kill my insulation installer for blowing cellulose in my attic after I told them I didn’t want it.
If you’re doing it yourself, consider recycled denim like UltraTouch. This insulation doesn’t leave you itchy. It’s dense and fits into the cavities securely. I did my parent’s attic with it and it was wonderful to work with. The downside is that it’s pricey and hard to cut. But it’s really good stuff. Well worth looking into for a DIY project.
Rotten roof deck caused by moisture trapped by insulation

If you’re installing insulation directly under the roof, like in a cathedral ceiling or attic ceiling, make sure to leave about a 2″ gap between the insulation and the roof sheathing. If you don’t, there’s a good chance your roof will end up like this.
If you install insulation directly under the roof, you have to air seal underneath of it, like with an airtight sealing. In the attic, you can install rigid foam board to the rafters and essentially create a cathedral ceiling in there.
There are different types of spray foam. Open cell, which is like what couch cushions are made of, and closed cell, which is rock-hard. They have different characteristics that you need to research in order to make a good decision about their use.
You do not want to install insulation on the attic floor and under the roof. This is a case of “more is worse.” The insulation on the attic floor will make the attic cold, and the insulation above can trap the moisture in the attic, leading to moisture problems if the attic space isn’t ventilated. But if you ventilate the attic, then the insulation under the roof is doing nothing. Don’t do it! Choose one location – either the floor or the ceiling and insulate it properly.
If you insulate and air seal the attic floor, then ventilate the main attic space according to code. No matter how good your air sealing, moisture will enter the attic from the living space. If this is trapped in the cold attic, you can rot your roof. So the attic has to be ventilated. Personally, I’ve seen gable vents work fine in homes but it’s all the rage to use soffit and ridge vents. Whatever. Just ventilate the space well to flush out moisture.
If you insulate under the roof, be sure to air seal under the insulation just as well as you would the ceiling of your home. The attic becomes part of the living space when you insulate under the roof. Treat it as such. Fail to do so? See photo above.

Ok, that’s enough. My fingers are tired from typing all morning. If you’ve read half of this and gotten this far, you should have most of the information you need to create a comfortable, efficient home that will last for decades.

Humidity Explained

Posted on April 17, 2015 by T.D. Inoue

Humidity. Moisture. Water vapor. Evaporation. Condensation. Mold. Rot.

These are all words that go together in people’s minds when the topic of humidity comes up. But what is it and why is it so important?

I’m going to try to explain this as simply as possible, so for the scientists and engineers reading – please cut me a little slack. I’m going for clarity over precision. However, if you catch the inevitable factual errors, please point them out so I can correct them.

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Why Doesn’t My Mini-split Heat Pump / Air Conditioner Work?

Posted on April 15, 2015 by T.D. Inoue

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I recently had an interesting question – a reader asked what could cause a Fujitsu mini-split air conditioner to cause the air to become *more* humid. In fact, they noted that the air became highly moisture laden and the house was just yucky humid.

I really scratched my head on this one because, from a physics standpoint, under “normal” conditions, this is impossible with a mini-split. Why? Because a mini-split system has an air handler unit in the house with the only connection to the outside (and outdoor humidity) is through a small hole in the wall where the electrical and refrigerant lines run. And yet it happened.

The questioner noted that multiple units were involved and that various parts of the electronics had been changed, and yet the problem persisted. He noted that he’d heard of a number of other people with the same problem. I admit, I was baffled!

Then it came to me. In fact, I had worked with an associate, helping them to track down this exact problem. While I can’t state with 100% certainty that the problems were the same, the symptoms are the same. In addition, I realized that my own home’s systems exhibited the same issues, but I automatically made the adjustments to make the systems work properly!

Here’s what’s going on…

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Understanding and Evaluating Heat Pumps

Posted on January 5, 2012 by T.D. Inoue

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Heat pumps are a bit of magic. But you use one in your home every day – your refrigerator. So if you can accept that your fridge works, somehow making 0 degree air from the 70 degree air in your home, plus some compressor action, then you should be able to accept that heat pumps can produce 95 degree air to heat your home while it’s 25 degrees outside.

I’m not going to subject you to a full lesson on thermodynamics and the refrigeration cycle. Instead, I just want you to accept the fact that heat pumps work on the same principles as refrigerators and air conditioners – they move energy from one place to another. In the process, they make one side of the system hotter and the other side colder.

Heat pumps, refrigerators and air conditioners all work the same way – they move heat from one place to another, amplifying the effect using a compressor and refrigerants.

Continue reading →

Ted’s Top Tips to Help You Beat the Heat!

Posted on July 20, 2011 by T.D. Inoue

Record temperatures are creating uncomfortable conditions all over. Here in Pennsylvania, we’re expecting near 100F temperatures for much of this week, while Chicago just suffered through a heat index of 115F!

Along with high temperatures come big utility bills because of all the air conditioner usage. In this post, I’ll give you some tips for how you can “beat the heat” without breaking the bank!

Why Things Get Hot

If you’ve read any of my posts, you know that I like explaining things because I want you to understand WHY things occur. Once you know why, you can figure out solutions yourself.

Why do we use umbrellas to block the Sun? We all know that it’s cooler in the shade because the sun radiates heat. So if you can block the solar radiation, you can block a lot of the heat that it brings.

Even if you’re in the shade, it can get darned hot! If you’re sitting in your house, you’re being shaded by the roof – no direct sun is hitting you yet you’re still hot. Why? Because there’s still a lot of heat coming in – from the hot roof, the walls, sun shining through the windows and hot air entering the house.

There are other things that heat your house in the summer. Some obvious, some unexpected. You probably know that conventional light bulbs put out a lot of heat. In fact, each light bulb acts like a little space heater. But did you know that every appliance in your home, from your television to your refrigerator, is also pumping heat into the house 24-hours a day? And your water heater, especially if you have an oil boiler for your hot water – those throw off a ton of heat!

Quick recap -houses get hot in the summer because:

Solar radiation heats objects in direct sunlight, like your roof
Hot air carries heat directly into your house
Hot air and solar radiation heat your walls
Solar radiation enters through windows and skylights
Appliances and lights produce waste heat that enters your home

Beat the Heat!

Now that you know what causes your house to get hot, let’s see what you can do about it. I’ll start with the easy ones and work up to ideas that require more changes or greater investments.

Wear light clothes. Ok, this one is so obvious that I’m embarrassed to write it! But simple things like shorts, a lightweight shirt and no socks make a big difference to your comfort level.
Drink ice water or other no-calorie drinks. Cold drinks help reduce your body core temperature, that’s good. But don’t drink beer or soda or eat ice-cream and expect to stay cold. Anything with calories adds energy to your body, and that energy makes you less comfortable in hot weather.
Use fans to circulate air around you, but only when you’re in the room. Fans cool you by speeding the evaporation of sweat and by carrying heat away from your body. But when you leave the room, turn off the fans or you’ll be wasting electricity AND adding heat to the air because the fan motor gets hot. Remember – fans do not cool the air!
Turn up the temperature on your air conditioner. A slight increase in the temperature setting of your AC results in a significant reduction in the amount it runs. For example, raising the setting from 72 to 76 can reduce the energy use by 25%. Use a fan and turn up the temperature and you’ll see the savings on your next utility bill.
Raise the temperature on your AC when you’re not at home. There’s a lot of debate on this one, but let me put it to rest – you save considerable energy by turning up your AC when you’re not at home. Yes, you have to crank the AC when you get home, but there is definitely a savings – you will save much more energy doing this than leaving the AC at a constant temperature all the time.
Open the windows at night only if it’s cool and dry. Natural cooling at night is a great way to cool the house only when the air is dry. A big use of air conditioning is to remove moisture from the air so if you open your windows at night or in the morning when it’s really humid out, you’re filling your home with water. After that, your air conditioner has to work overtime to remove that moisture. So resist the temptation to open up the house when the humidity is high.
Turn off lights when you’re not in the room. This is always good advice, but it makes even more sense when it’s hot out. Remember, those lights are little space heaters. The longer they burn, the more your air conditioner has to run to remove the heat that the lights put out.
Replace lights with high-efficiency bulbs. This requires a little investment but it pays off year round. Compact fluorescent and LED bulbs are much more efficient than conventional bulbs mostly because they convert more of the electricity into light. I’ve written more than enough about the direct energy savings from these bulbs. Stop making excuses and replace those bulbs!
Install a new fridge. And recycle your old refrigerator. The old energy hogs throw off an amazing amount of heat. A new, super-efficient fridge can pay for itself in a few years and it will heat your house less.
Add insulation to your attic. If you don’t have at least a foot of insulation in your attic, you’re probably under-insulated. If you have a house from before the 1980’s, chances are, you only have a few inches of insulation. Going from 3 inches to the recommended 14″ of insulation (maybe R-9 to R-42) will reduce the amount of heat moving from your attic into your home by about 80%. A good insulation job is something you’ll appreciate year round.
Shade your windows. Remember, a big reason things get hot is because of sunlight. Ideally, you don’t want direct sunlight entering the windows. The best way is by using trees or bushes to shade the windows. If that’s not possible, exterior awnings do a great job, though many people object to the aesthetics. If that’s you, then get interior cellular shades to block the direct light.
Get windows with heat reflective coatings. In recent years, window coatings have gotten truly amazing. A good window can block 90% of the heat from entering from the sunlight. This also protects your carpets from damaging UV radiation. An added benefit is that these same windows will hold in more heat during the winter and they’ll be less drafty. So replacing old, leaky, single-glazed windows with tight, low-e, double or triple-glazed windows can make a big difference in your comfort year round.
Install a white-roof. Depending on your climate and your current insulation, this may or may not make sense. If you have lots of insulation, than the amount of heat coming in from your roof can make very little difference. But if you’re changing your roof anyway, get a reflective roof. This can substantially reduce attic temperatures and therefore the heat entering your home.
Install a more efficient air conditioner. New air conditioning is usually my last recommendation. You’ll spend thousands of dollars and depending on where you live, you’ll may only use it a few months per year. However, if you have an old unit, it’s probably operating at less than SEER 10, so switching to a new SEER 18 unit can cut your AC bills nearly in half.