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Mission: HVAC 2017 – Challenge 7: Measuring Efficiency

by | Oct 31, 2017 | Mission HVAC

If you have ever faced sky-high heating or cooling bills despite feeling like your home or office is never quite the temperature you want it to be, you know how impactful system efficiency is. But how can you be sure if your system is running as efficiently as it should be? We asked Gustavo, Aaron, and Chris to explain how HVAC systems are measured for efficiency – and how it affects your wallet.

Gustavo: Smart Systems

For this mission, I took it upon myself to conduct most of the research. Based on my own personal experience in this field, as well as everything I have learned and picked up from working with family members, I answered all questions. This Mission helped me better understand how technology has helped our home and commercial building cooling systems improve over the years. Our cooling systems are now working a lot smarter and better than ever!

Q1: How do you measure the efficiency of an HVAC system? Are there metrics to measure for it?

A: These days with so much technology out there for us to use, measuring the efficiency of an HVAC system has gotten a lot better. For the most part, HVAC systems are required to be energy efficient in order to be able to operate at the peak level all while using a small amount of energy. By properly diagnosing and troubleshooting HVAC systems, technicians can make accurate and wise decisions to find the right solutions to the problems. All systems are meant to operate at certain “Rated equipment efficiency” by their manufacturers. In this case, cooling system efficiency ratings (CSER) is the field measured ratio of actual BTUs delivered into a building or home, therefore when the system is not performing at its required performance, HVAC technicians have to move quickly and find the problem causing the system failure or slowdown. When it comes to measuring the efficiency of a unit, there are many ways and situations this could be applied to. The most important thing for any customer to remember is to always pay attention to their AC unit and its operation pattern. Once they notice something not working as usual, then more than likely means their system is not operating at its max or rated efficiency.

Q2: How do you test HVAC systems to determine their efficiency?

A: Such tests and procedures like measuring air pressure in a system can help HVAC technicians determine the efficiency of systems. Gathering such airflow information from a system and its air resistance through its air systems will help calculate the delivered BTUs of a system. If the system is not delivering at least 90 percent of the rated equipment capacity, then technicians know there is a problem with the system’s efficiency. By performing duct system leakage tests on home, customers can also get a better understanding of their systems efficiency. By performing air pressure tests, technicians and customers can gather vital information on just how well a home’s system is performing and in return come up with the best solutions to getting a system back on track with its required efficiency.

Q3: What levels of efficiency are required for residential and commercial HVAC systems?

A: To start off, the Department of Energy added New Seasonal Energy Ratio (SEER) standards to be enforced in all air conditioners and heat pumps being used in our region. Going from the 13 SEER air conditioning units, to 14 SEER or higher units. This is a huge change in the HVAC world because it benefits everyone, and our earth. By doing this, the consumer gets a higher SEER ratio, as well as spends less money to run the system. Another efficiency requirement that I noticed is highly enforced in all of Houston, is the “Accurate HVAC load calculation” which lead to properly sized residential and commercial equipment. Oversized equipment may operate less efficiently and at a higher capital cost. This affects a projected budget and operating expenses. Also, oversized cooling equipment may cycle excessively or not effectively dehumidify.

Efficiency levels vary by states and companies. Texas however has very strict efficiency levels that cover ventilation controls, energy recovery, duct and plenum insulation, piping insulation and of course fans system power and efficiency. It is important to remember that in order to attain “Energy Star” status, air source heat pumps and central air conditioners must maintain 12 EER for split systems and 11 for package units.

Q4: How much money could an efficient HVAC system save on energy costs for residential buildings compared to one that is not as efficient? Commercial buildings?

A: The cost difference in bills between having an efficient HVAC system and one that is not efficient is a great difference. Replacing an old air conditioning unit with an energy efficient one could save home owners as well as business owners 20-30 percent on their cooling costs. When considering 20-30 percent throughout the year, this can add up to some huge dollar amounts savings. Besides having energy efficient unit, it is critical for these residential and commercial units to be installed correctly in order to get the maximum performance out of them. According to some HVAC experts, the difference between having a properly installed unit and one that is not could save or hurt home owners tremendously. Depending on the area of the country, home owners and business owners could be over spending or saving up to a few thousand dollars a year by simply making sure their HVAC systems are energy efficient and performing properly.

In commercial buildings, it is very important for them to have a system that is operating at its best due to the fact that the energy costs are a lot greater than residential ones. Homes and commercial buildings consume 40% of the energy used in the United States. Of the $2,000 the average American spends paying for energy annually, $200 to $400 could be going to waste from drafts, air leaks around openings, and outdated heating and cooling systems. By reducing these losses through energy efficiency upgrades, home and business owners can save lots of money and at the same time be more comfortable in their home or business.

Q5: How do HVAC professionals make systems more efficient?

A: Gladly, there are many things HVAC technicians can do to make systems more efficient. Some of those are as follows:

  1. Making sure systems are properly charged with the right and proper amount of refrigerant.
  2. Making sure all system components are working properly and/or being replaced if needed.
  3. Conducting home “seal air leaks inspections” to make sure the home or business is properly sealed and airtight.
  4. Conducting scheduled maintenance system inspections.
  5. Adding insulation to a home that has no insulation in the attic, basement or exterior walls.
  6. Recommending to the home owner and business owner that they install energy efficient windows, skylights and doors.
  7. Recommending to home and business owners that they install and set programmable thermostats that automatically regulate the temperature inside.

All the above-mentioned options are just some of the ways and options that HVAC technicians take when trying to make a system more efficient. At a home or a business, improvement done to it, and that will take off excess amount of work from a system, will pay off in the long run with very noticeable lower energy bills. A small positive change in your system can mean a large dollar amount drop in your energy bill.

Aaron: Efficient Technology

In mission 7 I had the opportunity to talk with Drew Doyle who is an experienced technician for a commercial and industrial mechanical company in Grand Rapids, Michigan. Drew’s years in the field provide really good information for system energy and efficiency.

Q1: How do you measure the efficiency of an HVAC system? Are there metrics to measure for it?

A: Most of the time a great way to measure the efficiency of a HVAC system is the run a load calculation on the entire building and then also take a look at the monthly utility bills.

Q2: How do you test HVAC systems to determine their efficiency?

A: The most efficient buildings today are rated as LEED certified.  This means that they utilize the most advanced technology to create a highly efficient and green HVAC systems.

Q3: What levels of efficiency are required for residential and commercial HVAC systems?

A: The required level for efficiency is really based on the state and local codes.  In Michigan, residential units can range from 80% efficient to 90%.

Q4: How much money could an efficient HVAC system save on energy costs for residential buildings compared to one that is not as efficient? Commercial buildings?

A: Efficiency can definitely save hundreds of dollars annually for residential and thousands for commercial buildings.

Q5: How do HVAC professionals make systems more efficient?

A: They make it more efficient by adding advanced technology into the HVAC system.  Different things like high efficiency furnaces and boilers use less energy with more advanced motors and frequency drives. Also, geothermal is a highly recommended system for saving energy in modern construction.

Full system closure is extremely important for getting the most out of your HVAC system. With the use of reflective foil tape leakage in a system will be reduced. This increases the efficiency of the fan and coil for maximum performance.

Chris: Maxing out Efficiency

Q1: How do you measure the efficiency of an HVAC system?

A: In my mind, the efficiency of a system is determined by the engineers who designed and tested the equipment originally. There are ways to test the input and output of the system based on its efficiency as defined by the engineers.

Chris mission 7 efficient HVAC systems

Q2: How do you test HVAC systems to determine their efficiency?

A: Outside of a lab, it is impossible for a system to perform at 100% (or even 90% in most cases) of its efficiency rating. In the field, we can test the actual output of a system in the cooling mode by using wet-bulb and dry-bulb readings to determine the load (sensible and latent) that is removed from the house by the system.

Q3: What levels of efficiency are required for HVAC systems?

A: In my part of the country, a residential unit with a SEER rating lower than 14 cannot be installed anymore. Required SEER and EER ratings for light commercial HVAC systems seem to be dependent on the size of the system.

Q4: How much money can a high-efficiency unit save vs a lower-rated unit?

A: Power savings are undeniable as the efficiency increases. One of our customers upgraded from a 10 SEER heat pump to a variable-speed 25 SEER HP and used the money they saved on their power bill to make the monthly payment on the new install.

Q5: How do HVAC professionals make systems more efficient?

A: Proper maintenance is a huge part of making systems as efficient as possible. Nu-Calgon says that a dirty condenser coil can decrease capacity of a system by up to 30%, so regular cleaning saves customers money and extends the life of the system. Ensuring that the ductwork is tight is also an important part of maintaining an HVAC system. Duct leaks (return and supply) result in an inefficient system as conditioned air is lost to unconditioned spaces or the unit pulls in unconditioned air and tries to condition it.

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