Understanding SEER Rating

In the middle of the real estate boom, the United States Department of Energy mandated making the minimum SEER rating of our HVAC systems 13 SEER or greater . This would go in to effect in January of 2006, and many builders and HVAC companies were warehousing older 10 SEER units for cheaper installations and parts. I was a real estate agent at this time and the decision was not popular with many of my colleagues. “It’s just going to make homes more expensive” and “my old unit works just fine, why does the government have to get involved” were the most common complaints. We didn’t like it, but honestly I don’t think any of us could have explained what a SEER rating even meant!

SEER stands for Seasonal Energy Efficiency Rating and is an average of the unit’s cooling efficiency. Simply stated, the higher the SEER, the more the efficient the unit. As a mathematical formula it would read:

Total cooling output over the cooling season / total energy input over the cooling season

Luckily many of the older lower SEER units installed before 2006 are long gone. The average lifespan of an AC unit is 10-15 years, but it is possible that if you are still running one of the old ones it could have a SEER rating of about 6. It is not uncommon today to find units operating at a SEER as high as 27 and while the upfront cost is higher, you will pay less over the course of its lifetime.

Below is a comparison of the cost of operating a 6 SEER unit compared to a 13 SEER unit. Both are 3 ton units (36,000 BTU) running 8 hours per day. We’ll say that the cooling season is 4 months long and the average utility rate is .10 cents per kilowatt hour.

6 SEER

36,000 BTU/hr. x 976 hours / 6.0 SEER = 5,856,000 watts / 1,000 (to convert to KW) = 5,856 KW x $0.10 = $585.60 per year

13 SEER

36,000 BTU/hr. x 976 hours / 13.0 SEER = 2,702,769 watts / 1,000 (to convert to KW) = 2,703 KW x $0.10 = $270.30 per year

This is an annual savings of $315.00 per year, or $4725.00 over its average 15 year life span. Rebates from your local power companies will often bring the cost of the higher SEER units more in line with the minimum SEER models, so be sure to check before purchasing.

Even if you are not ready to replace your older unit, you might want to consider having your duct system tested. 20-40 percent duct leakage is not uncommon and a homeowner repair is not difficult. Doing this now will ensure that you are milking every last ounce of cool air from your existing system. It is likely you will begin to save money without replacing your existing system! 

Will A Metal Roof Save On My Heating And Cooling Bill?

       

The answer to this question is yes and no; it will save money on your cooling bill, but the effect will be negligible on your heating bill.

 In addition to no maintenance costs, a metal roof, especially aluminum, can lower your demand for air conditioning. According to the Florida Solar Energy Center, installing a simulated cedar-shake aluminum roof can reduce heat gain from the roof down through the ceilings by as much as 34 percent. Steel roofs, although not as efficient as aluminum, are also better than asphalt shingles. A metal roof cools down in five minutes once the sun sets.

An Energy Star rating for all roofing products is based on TSR (total solar reflectivity). Classic black asphalt shingles will have a TSR of only 0.05, while a quality aluminum roof will have a TSR of around 0.40. The larger number will mean that the roofing materials remain cooler and less heat will be radiated down through the ceilings to the living area. Also the underside of the aluminum metal surface has a lower emissivity (the ability to emit heat) than asphalt shingles, so less heat radiates downward.

Follow this link to an Energy Star roof calculator: http://www.roofcalc.com/    before making any roofing decision.

Metal roofs can save you as much as 20% on your summer utility bill by keeping your attic several degrees cooler. You can increase the savings by adding a radiant barrier under the metal roof to reflect even more heat rays.  A radiant barrier http://www.energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11680  can also be installed inside the attic as a retrofit on any metal or asphalt shingle roof. Avoid a horizontal application because dust from your insulation will reduce the radiant barrier’s effectiveness over time. The best application will be between the rafters up against the underside of the roof.

So the answer to this question is yes, a metal roof can reduce you energy bills. I will add that a radiant barrier alone will reduce your energy bills as will lighter color asphalt shingles or shade from large trees. A new roof can be an expensive proposition and it is always wise to calculate your ROI (return on investment) http://www.greenandsave.com/master_roi_table.html  on any improvement.

Energy improvements on an older home: where to begin

             Energy improvements on an older home: where to begin

Before the fuel crisis of the 1970s most Americans never thought twice about their home’s energy consumption. Many lived in older homes that had been retrofitted with electricity, indoor plumbing and forced air heating and cooling, and how efficient these systems were was less important than the fact that were simply there. Efficient and installed were synonymous!

The air conditioner brought an explosion of growth to the southern half of the United States that had once been declared “too hot for civilized people” to live year round. These systems were installed in homes that were not designed for such modern equipment and the results were mixed. Basically as long as the system was blowing cool air the house was cool. These homes were just not good at holding the cool air. So let’s discuss a few ways to bring these homes up to reasonable energy consumption levels. 

Below is my priority list, but it is okay to skip around some if you can’t afford the next measure.

1.     Seal all balloon framed walls and attic penetrations (plumbing, wiring, HVAC).

2.     Seal and insulate attic hatch.

3.     Seal and insulate knee walls in attic area.

4.     Insulate attic to R-30.

5.     Seal and insulate all forced air duct work.

6.     Install vapor barrier in crawlspace.

7.     Seal all plumbing and wiring penetrations in crawl space area.

8.     Caulk and weather strip around doors and windows.

9.     Install bath fans and range hood.

I would consider this list of priorities as a baseline before I purchased any type of energy saving appliances. Of course if the appliances or HVAC system need replacing before you complete the list, do so with Energy Star models. 

I would also consider having a blower door test conducted by a qualified individual before attempting any work. By doing this problem areas can be identified and large amounts of air infiltration/exfiltration can be eliminated. It is a good idea to have the testing done by an impartial person and not a company that wants to sell you the improvements.

But I'm already saving energy

I was recently asked a question that, at least on the surface, seemed like a straightforward one…"There are several ways to save energy, but often times the payback on the energy saving device is close to 27 years because I already live a very energy efficient lifestyle. So the question becomes, "How does a person who is already saving energy make the improvements to their home that will yield a return on investment (ROI) and because they are the right thing to do.

I started to think of Energy Star appliances, a high efficiency water heater and other improvements that one can do after they have the basics covered. Then I thought I’d better ask them what they had already done to consider themselves energy efficient. I got the typical answer of “we bought a 15 SEER HVAC system, added some attic insulation, put in some CFL bulbs, you know the typical stuff.” There were a few more things that were added to the list during the conversation, but I never heard them mention any air sealing work that amounted to more than “spray foaming the pipes in the kitchen cabinet”. So I asked a few more questions.

Me-“What was your duct leakage number when the HVAC was installed?”

Her-“I don’t remember there being one, but the unit is 15 SEER!”

Me-“Did you air seal anything before putting the attic insulation in?”

Her-” We didn’t need to. The contractor told me that the insulation would seal up the holes and keep the cool air in.”

Me-“Have you noticed much of a drop in your power bill?”

Her-“Not yet, but this winter was pretty mild and we just installed the AC.”

This was a conversation with someone that considered themself energy efficient. I have to say that their intentions were good, and I certainly don’t want to make light of that, but they missed it by a mile. Step one in any energy conservation program with your home is air sealing…keeping the conditioned air in and the unconditioned air out. You must have a clearly defined thermal barrier before you attempt any energy saving measures. Well you don’t have to, but without it you will never reach your maximum saving potential.

I meet people every day that assume blown or batt insulation will keep the conditioned air inside their home; it will not, it simply slows down the heat transfer between conditioned and unconditioned space. Spray foam insulation will slow the heat transfer and air will not penetrate it, but it is expensive and if you already have some attic insulation it may not be worth spending the extra money. Sealing attic penetrations under the insulation before adding the new might be the simplest and cheapest approach. The payback will certainly be much quicker and it is something to consider doing yourself.

The 15 SEER HVAC was not a bad idea…if it needed replacing anyway. If it was still in working order you could probably have saved as much money by duct sealing as you did by replacing the unit. And if the ducts weren’t sealed properly on the new one, you won’t save a dime! The difference in Kilowatt hours (KWH) used by a 13 SEER and a 15 SEER is about 15%. If you used 10,000KWH to air condition your home the savings would only be $165.00 annually! (10,000X.15X.11kwh=$165) You could probably save that much in six months from duct sealing alone and I don’t imagine that the new unit will last long enough to ever pay you back!

There are a lot of companies out there that advertise products that will save you 40%-50% on your power bill. I don’t think any of us really believe this, and I think companies like this do more harm than they do good. You can make statistics say anything you want! I’ve monitored several hundred homes over the last two years and have documented some great energy savings, but a practical approach that is low in cost and done in steps will be the quickest path to putting more money in your pocket after the bills are paid.