We have been getting lots of questions regarding radiant barrier products. Radiant barriers seem to make sense to reduce attic temperatures in the summer. You may have seen the home show demonstrations where one side of a mock attic has a high pressure sodium lamp heating one attic with radiant barrier, and one attic without radiant barrier. These are very convincing demonstrations that you can actually feel or see the temperature differences. So does a foil radiant barrier product work?
Let me give you a background of where we are coming from as a US EPA Home Performance with Energy Star energy auditor and contractor. We use a science-based approach to reduce your energy bills and make your home more comfortable. That means our recommendations are based on a comprehensive energy audit using a blower door, thermal camera, energy modeling and heat transfer principals… not on a PowerPoint Presentation someone developed who probably is not an energy auditor. We have performed hundreds of APS energy audits and SRP energy audits so we have some experience under our belt and seen the benefits and a home that performs well, and the broken promises that are not only costly but bring down companies that do quality work. So let’s get back to your question.
Here are the facts -
1. In Phoenix, with an average of 360 days of sun a year, in a house with minimal insulation your home is only getting a maximum of 20% heat gain from the attic. We have written about the importance of your insulation being installed correctly in a previous post. The majority of your heat gain is through the windows.
2. Using the most outrageous radiant barrier savings claims of a 30% cost savings on your heating and cooling bill (sometimes even the sales rep gets confused and says it’s 30% of your total bills), let’s do the math. I’ve provided a radiant barrier savings calculator you can use to get accurate estimates on your savings below, just enter in your highest summer electric bill. Let’s say that’s $300 and 50% of that is from cooling. So that means you are spending $150 on cooling for, let’s be generous and say May, June, July, August, September (5 months). $150 x 5 months = $750 on cooling (overestimated). Then we’ll find how much of your cooling bills is from the attic (20% from #1 above) by taking $750 x 20% = $150. Now take 30% of $150 = $45. That’s your annual savings from a radiant barrier, $45!
3. If you are spending $2,000 on a radiant barrier to save only $45 a year, there are much better ways to save money on your bills! One would be to install a solar hot water or even solar electric system for a much quicker payment and ROI. That is why we will never recommend a radiant barrier product without tacking the big items found in a home energy audit first.
We hope that helps and feel free to leave comments below or like us on Facebook for a free Energy Savings Guidebook to learn how you can start saving today.
I know the summer is over in Phoenix and we can now enjoy the beautiful days on the golf course but we do use our furnaces or heat pumps to heat our homes and although not as extreme as the summer, the same HVAC tips I would like to share still can be applied to help reduce your electric and gas bills.
The Phoenix energy audit industry is very much married to the Phoenix HVAC industry because our energy bills are dominated by the costs associated with cooling our homes so I am always conveying important air conditioning tips during my energy audits to help cut those utility bills. In Phoenix there are two key air conditioning systems that are critical to ensure your system is operating as efficiently as possible and they are refrigerant charge and airflow.
In Phoenix, air conditioning accounts for 40% - 60% of your electric bill in the summer so it is essential to change your filters regularly. By changing the air filter you are not only breathing cleaner air but your house gets less dusty and it helps properly circulate the airflow throughout your house. Good airflow is critical to ensure your HVAC system is operating at its highest rated efficiency. If not, the HVAC unit ends up working a lot harder than it has to and shortens the lifespan of the air conditioning unit and parts.
Your refrigerant is critical to your air conditioning efficiency because it is the fluid that is responsible for actually providing warm air in the winter and cold air in the summer. Each air conditioning system has a specified amount of refrigerant it is supposed to have to work at its peak. Too much refrigerant and your HVAC system becomes overcharged and causes the compressor to work harder and possibly overheat. Be careful you have a trusted HVAC contractor who is NATE Certified because many air conditioning contractors will purposely add too much refrigerant into your system thinking it will help.
A refrigerant leak is equally as bad and is usually identified because the home will never reach the set thermostat temperature and your HVAC unit will keep running constantly without cooling or heating. It is not enough to simply add more refrigerant, homeowners should ask their HVAC contractor where the leak is occurring and have them repair the line.
Help! I have to run my clothes dryer at least twice to dry my clothes – a story from a SRP energy audit
During my APS energy audits and SRP energy audits I occasionally run across a home that has high utility bills but as I am going through my inspection of the air leakage, duct leakage, insulation, room pressures, HVAC system and ductwork there is not a huge problem identified. In one SRP home in Gilbert, I fell back on the homes motors, pumps and appliances and started exploring other options to pinpoint the cause. During this home’s SRP energy audit the homeowner informed me that she was running the dryer three to four times just to dry a load of laundry. It can be frustrating when it takes longer to dry your clothes than it does to wash them, especially if you have a couple loads of laundry to do. I know what that’s like, having bought a 1995 home in Phoenix with all original appliances. I hated having to run my dryer 3 or 4 times just to get my clothes dry! If you are in the same situation or you may even have a new washer and dryer set – before you go out to buy a brand new dryer here is a quick tip I found can save you literally hundreds a year on drying costs.
Your dryer is actually the second biggest energy using appliance after the refrigerator. Plus if you are having to run the dryer twice or more to get your clothes dry then it is using even more energy. The washer actually doesn't use that much energy, the costs for the washer come in when it needs to use hot water (try buying cold water detergent and seeing how your clothes come out). Your dryer vents can be anywhere from a couple inches to 20 feet of ducting to get to the outside. All that ducting collects lint inside and could clog the vent and decrease the efficiency of the dryer. By cleaning dryer vents at least once a year you will increase the efficiency of the dryer and help prevent the risk of fire. A good way to clean the dry vent is to use a shop vac or leaf blower and suck all the lint outside. You want to be sure to snake the whole system to prevent a buildup.
In this case the SRP energy audit recommendations was mostly around the home’s pool pump run time, recirculation pump, 4 combined refrigerators and freezers and the clogged dryer rather than construction defect upgrades. This homeowner was still able to take advantage of the SRP rebates available for the variable speed pool pump and the refrigeration recycling program as well as the duct sealing rebates.
Air conditioning in Phoenix accounts for up to 60% of a home’s annual electricity costs. It is not uncommon for energy bills to double in the summer time in Phoenix even if a homeowner tries to manage his or her energy use by switching to the APS and SRP time of use plan, only doing laundry and running the dishwasher at night, and setting the thermostat up during the day. Here are seven ways you cans save on air conditioning costs without spending thousands of dollars replacing your AC unit with a high efficiency unit.
Air Conditioning Saver #1 - Leave your doors open
No, not your exterior doors but your interior doors. Phoenix air conditioning companies have spread a lot of false information out there about closing your vents and doors. You want all the interior doors open or at least cracked to help circulate air back to the return. Here is a quick test you can do to check if your air conditioning costs are higher than they need to be. With the air conditioning on close a bedroom door and place your hand under the door to check if you can feel air coming out of the door. If you can feel air escaping, your room pressures are likely to be unbalanced every time the door is closed. Have an APS Home EnergyAuditor or SRP Home Energy Auditor do a home performance assessment of your home to actually measure the pressure in each room to determine if correction is needed.
Here is a quote from Home Energy Magazine's study on the effects of closing interior doors, "When all interior doors are open, the return air can pass freely through the doorways to the furnace. If the interior doors are closed, the air must pass through relatively small cracks under the doorways to return to the furnace. This results in higher pressures in the delivery ducts and end rooms, which are partially sealed off from the central room by the doors, and relatively lower pressures in the central room even if the doors are properly undercut as they were in these homes. These pressure differences increase the overall infiltration rate of the home and the ductwork, thus increasing heat loss."
Here is what SRP has to say also:
A: Because the air-conditioning systems in our homes are closed-loop system, they are designed to move a specific amount of air throughout the house. Closing bedroom doors causes the air pressure in those rooms to increase. The air-conditioning unit pushes air in but cannot get it back out, which causes the unit to force conditioned air out of the bedroom under the door and through cracks or leak around the windows, wall plates and ceiling fixtures and draw in hot attic or outside air through similar cracks and leaks in the rest of the house."
What about if you have teenagers or relatives are staying over or you have dogs that you don’t want in a room so you have to keep the door closed. We usually recommend a transfer grille or jump duct be installed to relieve the built up room pressure and can go over the options with you.
Air Conditioning Saver #2 - Seal the ductwork.
Between 20% to 30% of an average home in the metro Phoenix area is wasting conditioned air in the summer and heated air in the winter to the attic. If 60% of your energy bill in the summer is from air conditioning and 20% of that air is not being delivered to the rooms it needs to go to, that can add up to quite a bit of change over 5 years. HVAC contractors do not seal the ductwork even on a new, high efficiency air conditioner which is like driving a Prius with a hole in the gas tank. Sealing your HVAC ductwork not only saves money on your heating and cooling bills, it brings less dust in the home too.
Air Conditioning Saver #3 - Air seal your home.
Making sure your exterior doors are well weather-stripped, air sealing any electrical and plumbing penetrations and sealing any recessed canned lights will help keep your conditioned air inside and the outside air outside. A leaky recessed canned light can increase heating and cooling bills by as much as $5 to $30 per canned light.
Air sealing your home will also help stop the stack effect which causes warm air to rise and cool air to enter the home. If you have a wood burning chimney, a chimney pillow will help stop heated air from escaping in the winter and save on your winter heating bills. If you only have some areas of doors that you can see light through there are easy upgrades you can do with filler weather-stripping to fill those voids without replacing your doors. I know what you are going to say, don’t houses have to breathe? Yes, you need to have a supply of fresh air into your house for health and safety concerns but it is better to seal your home as tight as possible and bring controlled ventilation in from the outside than live with a leaky home and rely on dirty attic air as your “fresh air” for the house to breathe with. An APS Energy Auditor or SRP Energy Auditor will calculate the acceptable “breathing rate” of your home and compare that number with the measured “breathing rate” or house leakiness from a blower door test.
Air Conditioning Saver #4 - Install shade screens in the summer and remove them in the winter
Shade screens help reduce air conditioning costs by blocking up to 90% of the sun’s conductive heat through the windows. Windows account for more than half of the heat gain into your home just because they are transparent and have almost no insulation value. If you do replace yourhome’s windows, gas filled, vinyl windows are the way to go.
Shade screens are typically clipped onto the frame and can be removed during Phoenix’s winter season when we use our heat to get maximum sun exposure to save on heating costs. APS and SRP also give rebates for shade screens if you don’t already have them.
Air Conditioning Saver #5 - Go up to R-38 insulation in your attic
Is it a big surprise that Phoenix attics can get hot in the summer? That huge temperature difference between the attic and the house is another cause of rising air conditioning costs. Against popular thought though, the notion that the quantity of insulation is more important than the quality is completely wrong. It is more important how the insulation was installed than how much you have and a home energy auditor will be able to properly assess your home and tell you how much higher your air conditioning bills are than they should be.
Air Conditioning Saver #6 - Check if there is a direct connection from your garage to the house.
This is not a commonly talked about cause of high air conditioning costs but I have found this problem in houses in Glendale, Scottsdale and Gilbert. The garage is another area that can get very hot in the summer and like I said before, temperature differences are the main driver of heat gain into homes. Using a blower door, your energy auditor will be able to test the house-to-garage connection that occurs above the drywall where you cannot see and estimate the heating and cooling loss occurring from the problem.
Air Conditioning Saver #7 - Have your air conditioning unit tuned-up annual by a trusted HVAC contractor.
I personally know that finding a reliable HVAC contractor can be difficult. Even though you have a friend in the air conditioning business does not mean they will do a good job. I have been in too many homes where an AC contractor and friend installed a new unit and probably not purposely, but unfortunately cut way to many corners simply because that’s the way it’s been done for the last 20 years. After that is done, fixing any of their work is 10 times more difficult. First, the homeowner doesn’t want to point fingers at their buddy’s work, second the homeowner probably doesn’t know what “correct” looks like. Like a good handyman, every homeowner should have a good HVAC contractor.
Those are the 7 ways you can reduce your air conditioning costs dramatically. For others ways to save money on your utility bills be sure to check out our past articles and get up to speed on APS energy audits and SRP energy audits for your home.
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