What is ASHRAE?
If you aren’t in the industry, you might not have heard of ASHRAE (American Society of Heating, Refrigeration and Air-Conditioning Engineers). ASHRAE was founded in 1894 and is America’s standard for anything to do with “building systems, energy efficiency, indoor air quality, refrigeration and sustainability within the industry”, as it states on their website. First as a Mechanical Engineer at an MEP firm and then as an Energy Engineer, I had to read and use their codes and standards as part of the work I did. This is the case no matter where you work in the United States.
As we move forward as a society to become more energy efficient in terms of our building systems and our energy grid, we are consistently questioning our best practices. I came across these letters posted in the latest issue of the ASHRAE Journal, January 2022 issue. ASHRAE members critiquing a paper recently published titled “How Building Decarbonization Can Transform HVAC” written by Peter Rumsey, Jorlyn Le Garrec, and Avril Levasseur.
Hippies vs The Man
Before I share the excitingly nerdy results of the paper, I’d like to discuss how even within this widely accepted society there are debates and critiques on what is right and how, as a country, we can make our buildings an itty bit Better or more.
What I find interesting, and wanted to share to those who may not be aware is the push and pull within this one industry. A lot of people think it is one group of people against the other, tree huggers against the oil industry if you will. However, ASHRAE, as you may tell from their name consists of a many individuals ranging from manufacturing natural gas boilers, as well as Net Zero contractors. We are all on the same team, trying to provide comfortable spaces for you in a sustainable and cost effective solution. How we get there, is the question.
I bring this up because we see these conversations are happening everywhere, on the news, social media, television, or even with your neighbor. I want you to know that this is happening inside of the large industries as well. Is it worth it to “go green”? Well, for an individual, the answer isn’t a simple yes or no. It depends on your financial situation, comfort requirements, location, existing infrastructure, and future goals. For someone like me, my job is to make sure I find the best solution that works best for you, even if it’s only an itty bit Better, and not necessarily carbon free, but carbon less and that’s okay.
What the industry is doing is improving the technology, making greener solutions more affordable, and improving infrastructure efficiencies. If you continue to make itty bit Better improvements, the industry will be able to continue to make strides as well.
Together, our ultimate goal is carbon free because of what it’s doing to our planet. Whether you believe in climate change or not, fossil fuels are a finite resource. The sun and wind are not. So, I am here to say that even if you can’t afford to be carbon free right now, any small change matters…oh sorry, forgot to say itty bit Better again.
Are Heat Pumps a Good Source of Heat?
Back to the excitingly nerdy results…
The paper is the result of an analysis done by a team at Point Energy Innovations to determine if Heat Pumps are one viable source of heating for those who are looking to fully electrify their building.
Defined by ASHRAE, a Heat Pump is a
“thermodynamic heating/refrigerating system to transfer heat. The condenser and evaporator may change roles to transfer heat in either direction. By receiving the flow of air or other fluid, a heat pump is used to cool or heat. Heat pumps may be the air source with heat transfer between the indoor air stream to outdoor air or water source with heat transfer between the indoor air stream and a hydronic source (ground loop, evaporative cooler, cooling tower, or domestic water).”
In simpler terms and specifically for this discussion, a typical Heat Pump, used to cool or heat a space, utilizes the outside air to further heat or cool the space inside through refrigerant coils. Electricity is used to pump the refrigerant through the compressor in either heating or cooling mode and utilizes the difference in temperature between the inside and outside spaces, removing the need for natural gas or electric resistance heating, although electric resistance heating is sometimes used in extremely cold weather for additional equipment support.
The paper starts by reviewing the carbon impact of the grid, power plant or a renewable energy grid, along side the chosen heating source, natural gas boiler or electric heat pump. This sets a basis for carbon impact from distribution and transmission losses because even if a customer has a fully electrified building, it still isn’t truly carbon free if the electricity is being generated by natural gas; however, due to the efficiency increase between a heat pump and a boiler even if both are connected to a natural gas power plant, “heat pump heating systems would result in a 22% reduction in carbon emissions over on-site natural gas boilers”, the report states.
The paper continues by discussing the different types of electric heating and domestic hot water options most commonly used in different building types and applications: commercial, residential, multifamily, hotels, and other uses. It recognizes that electric heating in spaces or hot water may not be the best for every application, for example a heat pump water heater for a commercial building may not be cost effective unless it has a kitchen. Also, a residential home in colder climates may still need additional electric resistance heating to supplement the heat pump when the outside temperature falls below heat pump capacity (typically below 10°F to 20°F [–12°C to –6.7°C]).
For the team’s analysis, the building geometry created by using the U.S. Department of Energy (DOE) commercial reference Medium Office prototype building. Within the building, four different HVAC system models were constructed. The systems were based off what was most commonly seen in this building type, VAV reheat system. Then the hot water sources were switched out with gas boiler, heat pump, electric resistance heating, and a VRF system.
1. VAV reheat system with hot water sourced from a gas boiler
2. Same VAV reheat system with hot water sourced from air-source heat pump
3. VRF system with dedicated outdoor air ventilation
4. Same VAV reheat system with electric resistance reheat
In their combined efforts to give an answer to people reading this across the country, their models then used weather profiles from eight cities purposefully chosen in different climates across the country:
- Chicago, IL
- Denver, CO
- Miami, FL
- Nashville, TN
- New York, NY
- San Francisco, CA
- Seattle, WA
Results of these models included comparisons of energy, cost, and carbon reductions. I will just touch on energy and cost.
Overall, the heat pump and VRF system had very close results in terms of energy savings across the board. This was due to the gas boiler being less efficient and electric resistance reheat has a COP 1, which means the energy out is equal to the energy in, not ideal in most cases.
When cost is brought into the mix, we begin to see how the price of gas makes natural gas boilers competitive with the other systems. Just saving energy is not enough to bring your utility bill down. It is dependent on where you live, climate, energy rates, and how you use your energy. For Mr. Rumsey and his team’s energy cost results, I see the cities broken into 3 different groups:
1. Miami, San Fransisco, and Seattle’s cost difference between system numbers 1, 2, and 3 were so close it’s almost negligible. In Miami, all 4 systems were close because of the low heating requirements all year long.
2. Dallas, Nashville, and Chicago fell into the next group where systems 1 and 3 had very close costs, and system 2 had a small increase. In Dallas, though system 2 and 4 were higher in cost than 1 and 3, they were comparable. However, in Nashville and Chicago, system 4 was significantly higher.
3. The next category would be where there were more clear rankings between the systems in NYC and Denver. In order of best to worst, Denver’s system costs were 1, 3, 2, 4; NYC’s system costs were 3, 1, 2, 4.
In summary, heat pumps are a viable source of heating for a majority of the country. Is it the best? That depends on where you live and what your goals are. If you are only looking to save money, due to the cost of natural gas, a traditional boiler may still be the most cost saving option; however, if you are looking to also make your carbon impact an itty bit Better newer technologies are within reach, especially as the prices of technologies continue to decrease.
Feel free to reach out on any of my channels or leave a comment below if you have any questions! Do you have a heat pump in your home?
I work for a meat manufacturing company. I noticed we can be more efficient with our energy. The facility has no solar energy and the temperature is kept at freezing throughout the plant. The different manufacturing rooms are not separated by plastic hanging walls. The recycling room keeps its dock door open all day. We make uncured Salame, so the Salame rooms are all at different temperatures ie: each phase of the Salame has a different temperature. I also noticed the temperature gets colder towards the evening when staff is lower and the production is lower. Can you help us make this more efficient and save on energy costs?
Hi Marilyn, thanks for sharing and great observations! It definitely sounds like your company can improve their energy use. Closing the door behind you and improved insulation is definitely what you will want to start with. Keep a look out for my post this week where I will talk about the Energy Pyramid and the hierarchy of energy upgrades, it will give you a good place to start. Occupancy comfort is definitely important as well, you can’t make the sausage if your employees aren’t happy. Finally, solar, or any renewable energy generator system, that’s definitely last on your list of upgrades. You want to make sure your building is built properly and operating efficiently first. That is because if you are first saving energy, you will then require less energy to generate and therefore have a smaller renewable system to install, saving you money in the long run.
If you have more specific questions, click on my “Contact” page. You can send me an email, check out my social media pages. I am also offering my consulting services. Best of luck!