Air Conditioning Energy Ratings

BTUh, kWh, EER, CEER, SEER, SACC – when it comes to understanding air conditioner capacity and efficiency there are certainly plenty of arcane acronyms to sort through. The systems set up to allow objective comparison of air conditioners are hindering that very goal because of the many different measurement systems and terminology. Before discussing the different terms I would like to quickly explain what an air conditioner does: it pumps out heat. Much like a sump pump pumps out water from a basement or crawl pace, an air conditioner pumps heat out of your house. You need a sump pump that can pump water out as fast as it leaks in, or your basement will flood. With air conditioning, you need one that can pump heat out of your house faster than it leaks in, or your house will still get hot. The key point is that the air conditioner moves heat. In the United States we measure heat in British Thermal Units, or BTUs. The rate at which in air conditioner is able to pump out heat is given in BTUs per hour, or BTUh. This tells us how many BTUs of heat the unit can remove operating for an hour. The air conditioner’s electrical use is measured in kilowatts hours, or kWh.

EER Energy Efficiency Ratio

The EER is the easiest measure to understand. It is the cooling capacity in BTUh divided by the energy use in kWh. It tells you how many BTU of heat removal (cooling) you get for each kWh of energy. However, there are some things not taken into consideration. First is that it is a steady state test, meaning the unit is up and operating at full efficiency before any measurements are taken. No consideration is given for the energy used at startup, shut down, and while plugged in but not running. Also, all measurements are done at design condition, which is 80°F, 50% rh inside and 95°F outside.

   

SEER Seasonal Energy Efficiency Ratio

The Department of Energy devised this measurement for rating central air conditioning units in 1978 to address some of the issues not addressed by EER. Namely, cycling losses and operation at more than one temperature. The idea is that SEER is supposed to show the BTUh/kWh over a season, not just at one steady state condition. To simulate seasonal operation, SEER testing includes cycling and operation at  three different test conditions: 80°db/67°wb inside and 95° outside, 80° db/67°wb inside and 82° outside, and 80°db 57°wb inside and 67° outside. A unit’s SEER is generally higher than its EER because the SEER includes operation at milder conditions. Currently, the minimum SEER in the northern half of the US is 13 while the minimum SEER in the southern half of the US is 14.

CEER Combined Energy Efficiency Ratio

The DOE devised CEER in 2014 specifically for window air conditioning units. CEER is similar to SEER in that it measures efficiency at two operating conditions: 95° and 83°. It also includes the energy used while the unit is plugged in but not operating. A unit’s EER and CEER normally end up being very close to each other with the CEER being slightly lower.

SACC Seasonally Adjusted Cooling Capacity

The SACC was devised in 2017 to measure the efficiency of portable air conditioners. By portable, they mean the ones on wheels where the whole unit sits in the room and an exhaust duct is placed in the window to carry hot condenser air out. It is similar to the CEER in that it measures capacity at both  95° and 83°. It also includes adjustments for heat gains (cooling losses) from the exhaust duct plus loses due to infiltration caused by having to stick the exhaust duct out the window.

How do you convert between these different methods? You don’t because they each have different testing specifications. There are some formulas offered, but they can’t determine the differences in how different units will respond at the varying testing conditions.  The best you can do is understand each rating and use them to compare units with similar ratings. Just as the EPA mileage estimates don’t really tell you what your mileage will be with that new car you just bought, these ratings will not really tell you the energy use for your new air conditioner for a year. So which rating system do I believe is the most reliable? Honestly, the simplest and oldest one: EER.

Cranking Out The Rules

 With only weeks left in the Obama administration, federal agencies such as the Energy Efficiency and Renewable Energy Office (EERE) are finishing up work on a number of initiatives and publishing final rulings. Who are the EERE? They are a subset of the Department of Energy (DOE). These rulings have an impact on the HVACR industry. While the rulings do not have a direct effect on technicians in the field, they have a big effect on HVACR manufacturers. Indirectly they will affect us as manufacturers respond to the directives. Most of the rulings have to do with how different equipment is tested by the manufacturer, and in some cases, what equipment is covered.  Here is a list of recent rulings with links for more information.

12/02/2016 DOE Issues a Notice of Final Rule Pertaining to Test Procedures for Walk-in Coolers and Walk-in Freezers

https://www.regulations.gov/docket?D=EERE-2016-BT-TP-0030

12/01/2016 DOE Issues a Notice of Final Rule Pertaining to Test Procedures for Compressors

https://www.regulations.gov/docket?D=EERE-2014-BT-TP-0054

11/30/2016 DOE Issues a Final Rule Pertaining to Test Procedures for Central Air Conditioners and Heat Pumps

https://www.regulations.gov/docket?D=EERE-2016-BT-TP-0029

11/21/2016 DOE Issues a Comment Period Extension Pertaining to Energy Conservation Standards for Residential Furnaces

https://www.regulations.gov/docket?D=EERE-2014-BT-STD-0031

 11/15/2016 DOE Publishes a Final Determination of Compressors as Covered Equipment

https://www.regulations.gov/document?D=EERE-2012-BT-DET-0033-0012

11/10/2016 DOE Publishes a Final Rule Pertaining to Test Procedures for Commercial Packaged Boilers

https://www.regulations.gov/document?D=EERE-2014-BT-TP-0006-0049

10/07/2016 DOE Issues a Final Determination Pertaining to Energy Conservation Standards for Direct Heating Equipment  

https://www.regulations.gov/docket?D=EERE-2016-BT-STD-0007

10/04/2016 DOE Issues a Direct Final Rule Pertaining to Energy Conservation Standards for Miscellaneous Refrigeration Products

https://www.regulations.gov/docket?D=EERE-2011-BT-STD-0043

Regional Efficiency Reporting Rules

Right in the middle of the hottest and busiest summer in years the government is helping us by adding some more regulations and paperwork. The good news is that you probably already keep the records they are requiring. The Energy Efficiency and Renewable Energy Office (EERE) has just issued their final ruling on enforcement of the regional energy efficiency standards. The ruling requires equipment manufacturers, distributors, and contractors to keep records of the equipment they sell. It also requires that split systems be matched, and makes a distinction between uncased coils used as part of a complete system installation and those used as a replacement part.

The law on which this ruling is based is not new. It is Title III of the Energy Policy and Conservation Act of 1975. This specific ruling is new. It is a follow-up to the Regional Efficiency Standards. Although the regional efficiency standards have in been in place now since January 1, 2015, the details regarding enforcement are new.

What Equipment is covered by this ruling?
The Energy Policy and Conservation Act defines a “central air conditioner” as a “product . . . which . . . is a heat pump or a cooling only unit” and refers to all central air conditioners as one “product.” So when they say air conditioner, they are including heat pumps. Split system air conditioning and heat pump condensing units, cased coils, uncased coils installed as part of a new installation, packaged air conditioning and heat pump systems are all covered by this ruling.  NOT covered by this ruling are furnaces and uncased coils installed as replacement parts.

Who Must Keep Records?
Equipment manufacturers, distributors, and contractors must all keep records. However, the information you are required to keep depends upon which of these you are and what specific equipment is involved.

For every condensing unit, indoor unit and packaged unit installation, contractors must keep the following information for four years:

• Manufacturer
• Model Number
• Serial Number (NOT required for indoor units including blower coils, cased coils, and uncased coils installed as part of a new installation)
• Installation Location including the street address, city, state and zip code
• Installation Date
• Party from whom the unit was purchased, including the seller’s name, address and phone#

I expect most contractors already do record all the items on this list. Most manufacturers will want this information for warranty purposes. If you plan to service the equipment for the customer, you certainly want to know things like the model number, serial number, location, and date of installation. Since any properly installed system should last much longer than four years, keeping those records for at least four years makes perfect sense. Furnaces are not covered by this ruling. However, as long as you are keeping detailed information on the coil sitting on top of the furnace, why not go ahead and record the furnace information as well?

It is interesting to note that the condensing unit and coil are being listed separately. It is really not correct to say a condensing unit is 14 SEER, because it needs a matching coil. Since different matches yield different results, a single condensing unit can produce a range of efficiencies. To address this issue, the lowest rating point using the condensing unit manufacturer’s own indoor coil is what determines where a split system condensing unit may be used. So if a condensing unit has a rating of 13 SEER with one coil and 14 SEER with another coil, it will be considered 13 SEER unit. When using a third party indoor coil, the coil must be matched to the condenser. However, a third party coil may not be used to increase a condenser’s rating point above the manufacturer rating. For the purposes of meeting the minimum efficiency for your area, you may not use one manufacturer’s coil matched to another manufacturer’s condenser to obtain a rating higher than the condenser manufacturer lists. Obviously, this CAN be done, but it won’t qualify the unit as a 14 SEER unit if the condenser manufacturer lists a 13 SEER coil match for that unit.

Records must be kept for all cased coils. Records on uncased coils may or may not be required depending upon their use. If an uncased coil is a replacement part, you do not have to keep records on it.  An example would be replacing a leaky indoor coil on an existing system. However, if an uncased coil is used as part of a complete install, then you do have to keep records on that coil. You are not required to keep serial numbers on indoor coils. Many indoor coils do not have a serial number.

If you are looking for an easy way to keep this data, I suggest an Excel spreadsheet. Excel is a commonly used program and many of you may already have it. A spreadsheet does not take up lot of space and you can keep data on several systems on a single spreadsheet. Depending upon the number of systems you install in a month, you could have a spreadsheet for each month, or even one for the entire year.

I have put together a very simple Excel spreadsheet which you might like to use. The data handling functions of Excel allow you to sort and search data by different categories.  For example, a search of listings by model number or by address. Here is the link to download the file.
https://drive.google.com/open?id=0B0i1Mw3czgHrMmFwRlR4dzVWR1k


I encourage you to read it for yourself – as government regulations go it is pretty short. Here is a link to the ruling.
http://www.regulations.gov/document?D=EERE-2011-BT-CE-0077-0102

You might also like to read an excellent article by Jen Anesi in "The Air Conditioning, Heating, and Refrigeration News.”
http://www.achrnews.com/articles/132995-new-ac-reporting-rules-coming

DOE Small Motor Efficiency Standards for 2015

You may have missed the news about required small motor efficiency minimum standards while you were focused on refrigerant changes; regional efficiency standards for air conditioners, furnaces, and heat pumps; and trying to stay ahead of the latest news on climate change. I know I did. I was looking at the Grainger web site the other day and up popped a bulletin regarding the Department of Energy requirement that certain small electric motors 3 horsepower and under meet a new minimum efficiency requirement beginning in March, 2015. I immediately thought “oh bother,” that would include most of the motors we deal with in residential HVAC. Then I looked up some details and breathed a bit easier.  Motors which are exempt include multispeed, enclosed, specific purpose, or special mounting bracket. That just exempted most of the motors in residential air conditioning equipment. If you deal with regular mount, general purpose, 42, 48 or 56 frame capacitor start or capacitor start-run motors, you WILL be affected. An example might be ventilation fan motors. Grainger was not saying replacement motors would not be available, just that they would now have run capacitors and would be longer due to the extra windings required to meet the new efficiencies. Basically, this DOE ruling makes what was once the premium, high efficiency motors the minimum motor design for certain motor types defined by NEMA. I found several links with discussion and details on this requirement. They are listed below. You might want to take a look at some of these links to determine if you work with any of the affected motors. That way you can develop a replacement strategy before you get to a job and find that you will not be able to replace the old motor with another just like it.

Baldor http://www.baldor.com/news/article.asp?id=1014

US Department of Energy  http://www1.eere.energy.gov/buildings/appliance_standards/product.aspx/productid/40

Weg Industries http://ecatalog.weg.net/files/wegnet/WEG-motor-global-energy-efficiency-legislations-2015-and-beyond-energyeffleg-training-english.pdf

Design News   http://www.designnews.com/author.asp?section_id=1365&doc_id=271471

Evap Temp Effect on Compressor Capacity

I really appreciate the detailed data that some manufacturers have available to the public on the internet. For example, Bristol Compressors has detailed performance specifications for all of their compressors online for anyone to see. Not only do they have the specs for standard rating conditions, but you can also enter in your own. This allows you to see the effect that changing system conditions has on the compressor capacity, energy use, and EER. For example you can see what happens if the evaporator temperature drops from 45°F to 40°F. At first, that does not seem like a very big deal. But in the case of a Bristol H81J223ABC, that change drops the capacity from 21,800 Btuh to 18,800 Btuh and drops the EER from 9.8 to 8.9. Now ask yourself this question: “How easy would it be to have an evaporator temperature 5°F too cold because of a dirty air filter, dirty coil, restrictive duct, slight undercharge, partially clogged filter drier, incorrect piston (orifice), incorrectly adjusted TEV – and I am sure you can think of a few more.  In fact there are so many ways to be just a little off it seems likely to occur. Unfortunately, the effect on system performance is not little. The capacity drops by 14% (18,800/21,800 = 0.86 or 86%) and the EER drops by 9% (8.9 / 9.8 = 0.91 or 91%).  For a more dramatic drop in capacity, look at what happens to a commercial refrigeration compressor when the evaporator temperature drops from -10°F to -20°F. The Bristol L61J113ABC produces 7000 Btuh at its -10° rating point. At -20°F this drops to 3800 Btuh. At only 10°F colder, the compressor capacity drops to 54% of its rating! That extra 10°F colder costs dearly in electricity. With some creativity and exploration you can use comparisons of different operating points to illustrate many issues in HVACR systems.

You can find this interactive compressor playground at www.bristolcompressors.com Engineering Support > Compressor Search or just CLICK HERE  Enter whatever details you want to start the search. Once on the page for a particular compressor, click “Specific Point” towards the top right of the screen to enter your own operating conditions. Have fun!

Southface

The Georgia State Consortium of Air Conditioning Instructors met on October 25 at Southface in Atlanta. Southface is a non-profit agency devoted to energy efficiency and sustainability in buildings and communities. In keeping with their ideals for sustainability, Southface does not allow bottled water, box lunches, or  syrofoam cups in their facilities. I must admit, I was a little put out with all the rules. “Who do these people think they are?” But then I realized, they are actually practicing what they preach. They know who they are. A sponsor, Technical Training Aids, graciously provided our lunch wthin the confines of all the rules and it was great. We gathered there to hear about what Southface could offer and tour their facilities. They provided an overview of the new residential energy efficiency code and its application in Georgia. All new residential construction in Georgia is required to pass a blower door test and all new duct systems must pass a duct blaster test for tightness. Those two requirements are the big ones for HVACR contractors. Further, the people performing the test must be state certified to perform it. They get certified by taking a relatively short course that lasts less than a week and then passing a performance test. So at least in Georgia, installing tight duct systems is no longer an “add on” for the better homes, but a requirement. Although there will certainly be many contractors that will regard all this as a pain, at least one in Athens sees it as an opportunity. Anytime he sells a high efficiency changeout, he quotes a duct seal and wrap upgrade. A seal and wrap consists of removing the old duct insulation, sealing the duct, re-installing the old insulation, and insulating over the old insulation. The duct blaster is used to measure the duct leakage before and after the job to document the improvement. So even if you don’t work in Georgia, you might consider promoting duct sealing and insulation. If your competitors don’t do it, that is a way to differentiate yourself from them. Most homeowners can easily understand that leaky ducts cost them money. For many systems, sealing and insulating the ducts will improve system efficiency even more than installing a new high SEER system.