Power For Your Life Podcast | Season 1 - Episode 3
In this episode, we discuss ground-source heat pumps (GSHPs) with expert guest Scott Blue from Associated Electric Cooperative. We talk about what they are, if a GSHP is right for you, how to choose the correct model and size, what makes them so great and more!
Transcript – Power For Your Life – Season 1 | Episode 3
Original release date: December 2, 2019
I'm Rhonda and I'm a co-op member. I love my co-op because safety is a core goal. My co-op educates the public, students, contractors and local emergency personnel on the dangers of electricity. My co-op cares about its members.
Darryll (Host): Welcome to the Power For Your Life podcast, where we focus on energy efficiency, the value of electric cooperative membership and safety around electricity. I'm Darryll Lindsey, your host, and today's subject: what you need to know before installing a ground source heat pump in your home. With me today is Scott Blue from Associated Electric, Cooperative, and Scott manages energy efficiency programs in this area. Scott, you’ve been involved with energy efficiency and helping co-op members save money for a long time and we know that you've seen a lot of homes out there with high electric bills. What's the first thing that you would recommend to homeowners?
Scott (Guest): Thanks for having me today. I think the first thing we look at when we go to a home that's needing to update or replace their heating and cooling system is, we're going to focus initially on the requirement of that home--the BTUs needed to heat and cool it. Trying to get those under control. One-educate the member on insulation values, windows, leaky areas of the home. Focus on those areas and what that will do is get the requirement of that home-homes needs for heating and cooling down ultimately saving that member money over time. Then we get to focus on sizing the ground source to that home. What we do is we require a Manual J heat load be done on that structure and what that is-is a software program that we input data from the home’s materials, the windows, the framing, the insulation values, everything about that structure is placed into the software program. And we require a 70-degree design temperature typically and all that saying is the indoor and outdoor temperature will have a difference of 70 degrees. Once we see that and use the homes makeup, it spits out the BTUs required for that structure. And that's how we go about sizing a ground source unit to that home.
Darryll (Host): So, in-in this evaluation in this Manual J calculation, this isn't something that takes five minutes to do. This is a pretty extensive evaluation of that home, right?
Scott (Guest): It is. If we look at the all those materials. We look at overhang. We look at window size. We have to measure the home and all those things that go about it. You can even look into the lay of the land. The trees and the shading and other things that are there. The roof material, the color of the roof material, all that goes into that to create a real accurate representation of the home’s needs when it comes to heating and cooling. And then once we have that size were able to one, the geothermal is-is one unit that's going to heat and cool that structure. Where in the traditional setup you-you typically have an indoor furnace and you have an outdoor air conditioner. The requirement of that structure in our climate here is different between heating and cooling. You typically need probably twice the BTUs to heat a home in the winter than you do to cool it. And so, when you go to throw one piece of equipment and it needs to do both of those, sizing is very important and the accuracy of that is certainly needed.
Darryll (Host): So, let's talk a little bit about the benefits of heat pumps in general. I mean, there's-there's obviously geothermal, which is our main topic today…ground source heat pumps. But there's air to air heat pumps that do offer some heating and cooling benefits. Why would I install any type of heat pump in my home instead of going with a conventional electric heat, like you suggested, you know an indoor heating unit in an outdoor air conditioner that's a separate component or even a gas heating appliance?
Scott (Guest): Sure, it's a good question, and really it gets down to the efficiencies of those appliances and their ability to supply BTUs in the form of heat or to remove heat in the summer when it comes to air conditioning. Our typical forced air furnaces; if we were to look at an electric furnace, electric furnace is 100% efficient. It has a C-O-P of one and what that means is it's-it's going to produce 3,413 BTUs for every one kWh or one kW in size of that furnace in an hour. When we add an air source heat pump or mini split or a ground source, what we're able to do is take that same amount of input energy and sometimes produce two to five times the BTUs into that building using that same amount of energy. And the same thing with the forced air gas furnaces. Most of those I think we're probably topping out in the 98% efficiency range. And when we can do that same amount of work doing it at 200 to 500% efficient, it just typically makes sense to consider these appliances, especially when you're going through the process of getting bids and quotes. And this is where we would really leverage the knowledge of those efficiency numbers of those appliances versus the traditional systems. And then we would look at your utility costs, either from your electric cooperative and their kWh price. And we also look at your propane or natural gas if you happen to have that--the price that you're paying on that. And then we can get to using the Manual J heat load to tell us how many BTUs that structure is going to need annually. And we sort of work the problem backwards. We’re able to use those numbers as well as the price we're paying for energy to get to a sound answer as to whether it's makes sense to pay more for something that's more efficient. How soon will it pay off? Because that's all the member really wants to know, or we want to know is we're going to make a purchase here that costs more than a baseline system. And is it worth it? Is it going to pay itself off and should I do that? And we can certainly get to that. It really starts with the home--getting it is tight and as energy efficient as possible, requiring less energy over time. And then we're going to look at the cost of what we pay for energies and apply that to these efficiency ratings that we know exist on these appliances.
Darryll (Host): And I'm sure one of the other components that is included in here are the maintenance costs. You know you have to continually call somebody to fill up that propane tank, or you have to have you know certain things, certain relays, certain pieces of equipment need to be maintained inside any type of heating and cooling system. So those are probably factored in as well.
Scott (Guest): They are, and I think you know when we look at the ground source specifically, there is no outdoor unit. This-this is one unit that I said heats and cools both and it sits inside the home, so there's some benefit to that. We do have the loop field that we have to look at, but I think preventive maintenance when we look at any of these appliances is important that we're aware of, and we clean 'em. We change the filters, all those normal things that you hear about heating and cooling. But they’re like tires on a car. They get 15-20 years on ‘em and essentially we're getting to the point that we're going to have to look to replace them. But a good preventive maintenance on any of those appliances is very beneficial.
Darryll (Host): So, one of the statements that has been made by the EPA, the Environmental Protection Agency they've called ground source heat pumps, the most efficient, environmentally clean, and cost-effective space conditioning system available. So, if you specifically look at geothermal systems, what makes them better than any other heating and cooling system as the EPA claims?
Scott (Guest): I think their efficiency is one. It is all electric, and so we're looking at our utilities and their energy portfolios and that tends to lean a little bit more towards the cleaner energy aspect than we would say propane or natural gas. But they also are doing the work much more efficiently. They're producing that energy and moving that heat in or out of the home at 500% efficient. And none of those other appliances can compete at the efficiency and the amount of work that it's accomplishing compared to the energy input that it's utilizing. And so, it's a very green technology, I think, it uses the earth to store heat and return heat to the home and it moves that heat through that system much, much better than any of those other appliances. And I think the EPA has recognized that as well as adding that federal tax credit that they continue offer for that for the next few years, I think shows that they believe in that as well.
Darryll (Host): So, if you look at all the characteristics of ground source heat pumps, there's the potential there for the win-win for that member. Wouldn't you characterize that to be pretty accurate?
Scott (Guest): I would Darryll. I think for the most part we get to when we're looking at purchasing a heating and cooling system, I think it's best to probably look at one or two options when we want to consider what we want to go with. We also want to get two or three bids on those as well. And so, what I mean by three options, you may just look at a traditional based system. Most homeowners, when they're building a new home, for example, the heating and cooling is typically the last thing that goes in the home. And unfortunately, most of the money is probably been spent elsewhere. And so, early on we thought ground source was going to be what we wanted, but when we get to the end the money is just not necessarily there. But you certainly want to say--a base load system and then maybe consider what we would call a dual fuel system; an air source heat pump maybe tied to a propane back up. And then we would look at the third system of the ground source and sort of way the cost differences between those three options as well as their efficiency gains. And that gets us back to using the heat loads to really quantify those numbers for somebody. Usually it’s probably maybe in the six/eight-year payback when we wanted to look at maybe a mid-grade system and then upgrading to the ground source. And so, some people may not see that is beneficial if they're looking at this as a five year home or a stepping stone for them. But also think it's good to look at when you go to resell a home. You're--most people are going to look at energy bills and what is the cost of heating and cooling the structure, and can I afford the home mortgage as well as the heating and cooling bills? And I think it's a good sales point regardless. So, one if you can save some money back and plan for the ground source and build this home around a ground source unit, I think it ultimately gets you the win at the end.
Darryll (Host): Very, very interesting points there about all of the options and all of the factors that really do need to go into it. You know there's some technical aspects of any type of heating and cooling system that that one needs to know about. We're going to take a short break, and then we're going to come back and explore some of those technical terms and share how quickly you might be able to recoup the costs in terms of energy savings….when we come back.
Darryll (Host): Back with the Power For Your Life podcast and visiting today with Scott Blue from Associated Electric Cooperative about ground source heat pumps. Scott, let's talk about some of those technical terms that members need to be familiar with. Terms like C-O-P and E-E-R. What do they mean and what is their significance in layman's terms?
Scott (Guest): Those are definitely two-two ratios that give us an indication of the efficiency of the ground source. And so just 'cause you're buying a ground source does not mean you're not able to purchase different levels of product amongst the ground source. There's-there's the baseline model of ground source, and then we can get more into the Cadillac models. But C-O-P is coefficient of performance and I think it's probably the easiest one to remember. When we look at an electric furnace, it has a C-O-P of one meaning it's 100% efficient. And so when we look at these ground source units and they may say a C-O-P of three or five or even seven, what that's telling us is that at a C-O-P of five I'm getting five times the BTUs out of that one kWh of electricity; essentially saying it's 500% efficient at what it's doing. And so those are just good ones to look at it. It's a good way to gauge different ground sources between other manufacturers and also other models within that same manufacturer as you're looking. So you can get options amongst them. E-E-R is the energy efficiency ratio. Again, that's the ability of this ground source to remove heat from your building in the summertime, in BTUs versus the input wattage-one watt--how many BTUs am I going to get out of that building? And so those two are sort of synonymous with each other. As one gets more efficient, the other follow suit, but the C-O-P I think is the one that you--is easiest to remember. Electric furnaces-a C-O-P of one, and as we go up from there, that's essentially how many 100% efficient more it is over an electric furnace.
Darryll (Host): So, in addition to some of these technical terms and the items that you have to have to make the system operate properly, probably the most important one is that ground loop. So, describe briefly what that-what all the ground loop entails; what's involved in it? It's plastic pipe and sometimes plastic pipe buried in the ground is a-is a concern for some folks, especially the liquid that's inside those plastic pipes. So, let's talk a little bit about the loops.
Scott (Guest): Sure, there's typically I think three ground loop styles that we typically see, or just three loop styles. We would typically--we do have a ground loop scenario. In that one we have two options there. Typically, we’ve gotta vertical or horizontal type loop design, I guess when we talk about ground loop. More so than not, we see vertical just being in the area that we're in with rock and other issues. The horizontal one could run into issues and horizontally you typically probably want to be four to six feet deep. You want to go around 100-150-foot-long for each what we'd say is a trench. You have one trench for every one ton of capacity of your unit. And so, if you had a four ton, you would have four trenches 150 feet long. They'd all tie together in a header and then come into the home. Vertical is nine times out of ten what we see. Same thought process there. Typically, we would see one hole drilled 100-150 feet deep, maybe 200 for every one ton of capacity of our ground source. It uses that earth is the medium to store heat or to recapture it and put it back into the home dependent if you run heating or cooling mode. It also uses a glycol solution in that tubing. Most of that tubing, I believe that’s probably a 100-year life warranted against leaks. So, it should last several systems in that home. But it uses the earth as the medium to store that energy and put it either in the home or-or take it out of the home and put it in the earth. We also would see-every so often we see an open loop system. And open loop system does not have a loop field. It's using a water source and it's typically well water; a home in the country where we're going to pump well water into our ground source unit and use that water as the discharge or recapture of heat. Usually it's I think it's around 2-2 ½ gallons per minute per ton. So, if you have a four-ton system, you could see 10 gallons a minute of water needed while that systems running. You have a couple of options with the discharge of that water. You can run it off into a creek. You can run it into a pond. You can--I think the best option there maybe is a re-injection well. So, you would drill one well and re-inject that--that potable water back into the earth and put it back in the water table. But that's the open loop system and I think the third system that we see occasionally is what we'd call water loop. So, they’re taking the plastic tubing and sinking it into a lake. I think you typically want to get 10 or 12 feet deep with that option. And you need a fairly large lake to sync that pipe and keep it down. And so those are the three loop options. Again, I think the ground loop vertical is 9 times out of 10 what we see and then the horizontal and then we get into an open loop. Lake loops are just not something that we typically see in our service territories I don't believe.
Darryll (Host): Very, very environmentally friendly is really the bottom line for any of these loop options.
Scott (Guest): They are very much so.
Darryll (Host): Scott, we've talked a lot about some technical aspects of ground source heat pumps. We've talked about the environmental benefits. There's also some financial benefits as well. Talk a little bit about the tax credits that are available on some other options for members.
Scott (Guest): Sure. I think the tax credits are very useful and beneficial to most folks. The tax credits currently with ground source is at that 30% federal tax credit through the end of 2019 and then after that they're going to drop. It drops to 26% through 2020, and these are systems install and completed in those years. And then it drops to 22% through 2021. I think some other benefits too is a lot of your local electric cooperatives probably offer a real nice rebate per ton on some of these systems installed. It really helps lower the cost of that unit when we're looking at comparing them in the bidding process. So really gotta factor a lot of those things together when we go to look at whether or not it's worth purchasing one of these and financing it. Sometimes it's the best time to do it if you're building a home and can roll it into you know your overall build cost. And the return on investment is probably there for the--for that choice to be made. But definitely look at your tax credits and check with your local electric cooperative. There's probably some good incentives for you there to help finance this.
Darryll (Host): Scott, thank you for your time today. And—and again, check with your local electric cooperative for more information and more details about a ground source heat pump.