[Nick Redding] It may sound like a throwback, but for many folks out there, energy retrofitting is the “it” thing when it comes to reducing heat loss and energy costs. Fortunately for us, Ed mentioned Tom Marston, leading members of the nation’s first energy retrofit company, Energy Services Group, join me today to discuss what this kind of work entails, how it all got started, and some of the pros and cons of energy retrofitting in terms of building preservation. Get ready to bundle up, this is Preserve Cast.

This episode of PreserveCast is brought to you by Howard Bank. Howard Bank, we’re not just your branch; we’re your roots.

From Preservation Maryland Studios in the historic podcast district of Baltimore, this is PreserveCast.

[NR] This is Neck Redding, and you’re listening to PreserveCast. Today we’re joined by Ed Minsch and Tom Marston both with Energy Services Group. And we’re going to be talking about all things energy and energy retrofitting when it comes to historic buildings, which is a big topic and an important one. One that we get a lot of questions about here at Preservation Maryland. So Ed and Tom, welcome to PreserveCast.

[Ed Minch] Thanks, Nick.

[Thom Marston] Thank you, Nick.

[NR] Yeah. Great. One of the questions that we always try and open up these interviews with is, we love to get a sense for how people came to their careers and to these little niches in historic preservation. And so we thought we would jump in with that. And maybe, Ed, if you want to take the lead on that and kind of give us the story on how you found your way to what you’re doing today.

[EM] Fresh out of college in 1970 – my brother graduated in ’72 – the two of us started building solar homes. Have to remember that was a big time for solar homes. And over the next eight years, I think we built seven or eight of them. And then he wanted to do just plain old architecture. He didn’t want to get involved in construction anymore. So I looked around for something to do. And I found a group at Princeton University that had been given a lot of federal money- this was when Jimmy Carter was president in the late ’70s – to figure out how how houses lose heat, and what you can do about it. And through the late ’70s and up to about ’81 when I met them, they were developing an energy audit. They were developing mathematics that showed us better what insulation did. Figuring out what air infiltration did. How much money you’d lose to just leakiness in the house. Understanding that, they put together a set of tools. First of all, a big fan that fits into your front door. It’s called a blower door. It sucks the air out of the house, which makes all the leaks leak inward. And as all that leakage comes through the house and out the door, you can measure it. So it lets you put a number to how leaky the house is. Second thing is they adapted the use of infrared equipment. Infrared lets you look at temperatures of items by color. So I can see a cold spot in a ceiling missing insulation. I can see a cold spot around a window, which would be an air leak through the wall. I can see what’s going on inside the walls. And they also looked at -because your furnace was, typically at the time, never tuned up. You very rarely tuned up boil heaters but never gas – they looked at the heating system, too. They put together a package with the blower door, infrared the scanner and furnace analyzer. I saw them in National Geographic in 1981 in February. By the end of February I’d been in an attic with them, and by April, I had purchased franchise number one.

[NR] And is that Energy Services Group?

[EM] That’s Energy Services Group.

[NR] So you’re really probably one of the very first energy audit firms in the nation.

[EM] We are the oldest in the country. We’ve been in Wilmington, Delaware since ’81. That’s about 36 years now.

[NR] And from day one you were always in historic buildings as well?

[EM] First historic building- we did a bunch of museums for the State of Delaware in 1984. So it goes back to that.

[NR] Okay. So, Thom, was your path similar? Were you on the ground floor during the Carter Administration?

[TM] Nick, I was on the path from the Carter Administration, but on a different trajectory. I was at a utility at the time, Delmarva Power Delaware, and they had a process called residential conservation services. Send all editors out in to the field to help homeowners diagnose energy problems. And I didn’t have the education that Ed had with all of the equipment. Mine was mostly visual, and perception of where the problem exists. So when I arrived at Ed’s house he contracted for the $15 audit, I showed up. I think I know what I’m talking about. After an hour, I realized I don’t know what I’m talking about [laughter]. And I’m highly trained. I have a certificate. And over the next nine years I stayed very close to Ed, looked at what he was doing, and worked in my sister’s new house under construction, and I basically learned that this process of visual inspection really doesn’t hold up when you compare it to performance testing, a blower door, infrared. Today we do duct-leakage testing, and it’s much more vital that we actually measure the details. Now, I can look at an attic and say, “You only have four inches of insulation. You should have have twelve and make an economic justification for it, but I can’t say the house is leaky without measuring with a blower door. So that morning, sitting at Ed’s breakfast table– and it’s funny. His wife said, “Ed, don’t give the young man a hard time.” I later learned that his wife, her father and my mother had a relationship back in Wilmington, so it was very interesting how we blend our history and our current practices. But I learned a lot from this man. I call him The Doctor because he has a p.h.d., which we jokingly say is a Princeton house doctor certificate Ph.D., all little letters though.

[NR] And is that p.h.d from Princeton?

[EM] I have the training that I got through the franchise, but they didn’t give you the certificate. So I have no Ph.D.

[TM] Ph.D., Princeton –

[EM] Small P.

[TM] – house doctor.

[NR] Princeton house doctor.

[EM] Small P. Small P.

[NR] Okay. You got me as well on that one then. So energy retrofitting, I think that conjures up different concepts in different people’s minds. What is it? What’s the definition of it? How does Energy Services Group and Marston and Minch approach this?

[EM] An energy retrofit looks at all the areas the house that can lose energy and improves them as much as possible. We’re always looking at the ideal. Where do we want to be? What should this house look like? And then we look at how close we can get to that economically. And the only way to figure this out is to do an energy audit. To reach a retrofit, you have to do an audit. And an audit includes looking at the air leakage network in the house, the insulation blanket that surrounds the house. And it looks at the heating equipment, duct work and so forth. And for about the last eight or ten years, there’d been some safety issues that have been included in the audit by the Building Performance Institute, the B.P.I. They’re sort of the governing entity over energy auditing in this area, Middle Atlantic. So we look at the safety of the combustion equipment. We look at mold, moisture sources. Repair those things that we need to before we tighten the house up and proceed.

[NR] Now, is it any different– do you approach it differently when it’s a historic structure or are there different concerns that a historic property owner or a manager should think about as they’re approaching that kind of work?

[TM] The historic house is just an older home and has less insulation, may be wood frame or masonry. And we have 1950’s houses that are both wood frame and masonry. The historic overlay says we want you to limit your improvements in certain ways because we want to maintain the appearance. For example, windows, it is very contentious. We don’t want you to take out that single pane wood window. We want you to do this with it. And we know we want higher performing glass in homes. We want to make sure wood isn’t exposed to moisture. And when we tighten a house, we tend to get a more humid house. So if we leave a wood window in, that single pane has a great opportunity to be where all the moisture condenses because it’s very cold in the winter. So really historic doesn’t have any complication other than we would like you not to touch those things or make that visible part different looking.

[NR] But I think that’s an important point though to clarify because I think there are some people, and I think that this is beginning to change, but there has been a thought out there that, “Well, my historic home is old. Therefore it can’t be energy efficient or there’s some limitation on my ability to do that.” And I think that is beginning to change but even if you leave your historic wood window in, which we here at Preservation Maryland would highly recommend, there are still other ways obviously of achieving a higher degree of energy efficiency for a historic home.

[EM] Working with a historic home the audit is the same, the ideal is the same, but the way to get there is a little bit more complicated because you’ve got limitations. Some areas, Baltimore in particular, says that even in the interior you can’t change some things. Most places it’s just the exterior. I’m on the historic commission in Chestertown which has they say more 18th century buildings than any place in Maryland outside of Annapolis. And we don’t look at the inside of the house. You can do what you want in there. You can tear down some walls or whatever you like, but it’s the outside we’re concerned with. As an example, in Baltimore though if I wanted to insulate a brick home, I’d have to increase the depth of the wall toward the interior. They don’t want you to do that because as you walk by the front of the house and look through the window, you can see the additional depth of the wall. To me, that’s just making it hard on someone who’s willing to live in one of these old houses and fix it up.

[NR] So let’s talk a little bit about that. What if you do own a historic home and what– obviously, it all starts with the audit. We heard that a couple times now. But from your experience with a historic brick home built in the 1840’s, really no insulation, what are some of the common practices that you would employ to increase the energy efficiency of a place like that?

[TM] Staying with Baltimore city, a lot of these 1840s homes are being taken back to the original structure, so a masonry wall, wood floor joists, wood rafters for the roof. And at this point, we’re in the term “gutted shell,” so there is nothing that is off the table we don’t have any limitations unless we’re not taking that house apart.

[EM] On the brick exterior walls we see three conditions usually. The first one is the interior plaster’s right on the brick. You rap on the wall and it feels like a rock, right? There’s not much you can do with that. You have the insulation value of the brick, which is about one an inch. So an eight inch wall is R-8, which isn’t very much. We’d like to see– and the current codes for new houses is an R-20, which is more than double that. But if the plaster’s right on the brick and you want to leave that there’s nothing you can do with it. The second thing is a narrow gap. A small furring strip gap we call it. A three-quarter inch piece of lumber is nailed onto the wall. The plaster’s hung on that leaving a little tiny gap back there. We don’t have a material that we can fill that with and guarantee you’re going to get a good result out of it. The third result would be if you were rehabbing the house, and gutted the wall, and all you saw was the brick. You could build a 2″x4″ wall inside. That makes that thicker wall. You lose some floor space with that, but that allows us make a modern wall out of the thing, and the way we do it in Baltimore- one way- is to spray a two-part closed cell foam over the inside of the wall which creates a vapor barrier which keeps moisture from moving to the outside in, which it can do. If it rains heavily outside, some of that moisture can end up instead.

[NR] Right, because brick can actually kind of absorb that.

[EM] And the foam will stop that right there.

[NR] You threw a phrase out there which I think I’m familiar with, but maybe not all the listeners are. Closed-cell foam. What’s the difference between a closed-cell and an open-cell foam? Pro? Con?

[EM] There’s two types of foam. Closed-cell foam is a good vapor barrier right from the get go. Open-cell foam, you need 5 inches. I believe it’s 5 inches to get a vapor barrier, and we’re not going to put on 5 inches anywhere in the house. Closed-cell foam is much, much more expensive, triple– sometimes triple the cost of an open-cell foam. So we would like to use it only where we need to use it, and there’s only very few places where we need to use it. Inside this brick wall is one spot. We can put two inches of that on there. It’s worth about an R6 or 7 an inch, which gives me about an R12 on top of the brick. Now I’m getting up there. Then I build my 2’x4′ wall inside and put an R13 bat inside that. Now I got a really good wall. It’s airtight, which is the first thing we want; every square foot of the house has to be airtight. And it’s insulated, which is what we want. Every square foot of the house has has to be insulated. So that’s the ideal wall. We’re looking at that. If Baltimore says you can’t thicken the wall because they don’t want to see it from walking by on the sidewalk now you’ve got to come up with a different solution for that. Another way is to put a material that has drywall and a rigid foam board on it tacked right up to the wall. So you don’t get a lot of depth increase out of it, but you get some increase in R-value to it.

[NR] So what exactly is R-value?

[EM] R-value is a measure of how fast heat moves through an object. If I’ve got a glass window in my car, I put my hand on the window, I can feel the outside temperature. It has a very low R-value. It lets the heat of my hand and the cold of the outside go through very quickly. If I add more material, I increase the R-value. If I double the R-value, I cut the heat loss in half. That’s a very simple equation. So for our purposes in a historic house a single pane window is R-1. A double pane window is R-2. That’s why we do it. Because doubling the R-value has cut the heat loss exactly in half coming through that glass. If I go from a two to a four I cut it in half again. If I go from a four to an eight, I cut it in half again. By the time, in our climate, I reach about an R-30, there isn’t much left to gain. So right now the code says R-49- a huge amount- sixteen, eighteen inches of insulation in your attic. They require that. A thousand square foot of attic saves me about $10 a year over an R-30 attic. To add 50 percent of the 30 on top of it, I’m only saving $10 a year. So once I reach about an R-30, the rest is sort of gravy. It’s expensive. It saves a little bit, but it’s not very cost effective.

[NR] So there is some practicality, this issue with–

[EM] There is some practicality. The more you have, the less you need.

[NR] Alright. Well, we’re going to take a break right here. And when we return, we’re going to talk a little bit more about attics and what kind of work can be done there and the good and bad of an energy retrofitting. We’ll be right back here on PreserveCast.

And now it’s time for a preservation explanation.

[Stephen Israel] As you may have heard Ed and Tom mentioned, they are in fact based in Delaware, not Maryland. I know what you’re thinking this podcast is by Preservation Maryland. Dela-why are you talking about Delaware? Well, the truth is there is cool history stuff to be found wherever you look. So I thought I would take this as an opportunity to talk about some of the wild ways in which Delawareans have contributed to historic preservation. And not just any Delawareans. Today, I’m talking about the du Pont family.

For those unfamiliar, the du Pont family in Delaware are tied closer together than possibly any family state combination anywhere in the country. Pierre Samuel du Pont de le Nemours. The son of the Parisian watchmaker father and a mother with a very minor noble connection, first immigrated from France in the year 1800. By 1802, he founded a gunpowder mill on the banks of the Brandywine River near Wilmington, Delaware. Today, the business that he started is one of the biggest chemical and engineering companies in the world, and at one point employed ten percent of the state’s population. And you can still visit the site of the original mill as part of the Hagley Museum. The history of the du Pont family obviously helped to shape the landscape and history of Delaware as well as the United States as a whole. But in the 20th century, some members of the family decided to try and give back by helping to preserve American cultural heritage. Louise E. du Pont Crowninshield was a founding trustee in the National Trust for Historic Preservation in 1949 and vice-chair in 1953. Louise was not the only du Pont to dedicate a large part of their time, energy, and fortune to making history and preservation available to the public at large. One of the other more significant family members was Henry Francis du Pont, Louise’s brother, who had a personal passion for collecting pieces of American history be they art, furniture, or any other miscellaneous Americana at his family mansion Winterthur. Having been open to the public in 1951 by Henry before his death in 1969, the once private 175-room mansion is now a museum that houses one of the most valuable collections of Americana and fine art anywhere in the world and is still open to the public. You know, Maryland’s pretty great but that mansion might warrant a quick trip next door. Of course, only after you’ve finished listening to PreserveCast.

[NR] Do you have questions? We may have answers if at any point during this podcast you’ve thought of a question that you have for us or maybe one of our guests, we’d love to hear about it. You can send an email to and we’ll try and answer it right here on the air on the next episode of PreserveCast.

[NR] This is Nick Redding and you’re listening to PreserveCast. I’m with Ed Minch and Thom Marston of the Energy Services Group and when we left, we just sort of got a great definition of exactly what R-value is. And we were talking about how you could insulate a brick wall and all the details associated with that, and closed-cell versus open-cell foam. And one of the other big areas that people talk about a lot- I guess there’s two that we hear a lot about here- one being basements and then, of course, the attic. The dreaded attic that is either always hot or is always cold. And we get a lot of questions here at the organization, and I’m sure other preservationists do around the country, about when you have a historic roofing material and you have an uninsulated attic. It’s a walk-in space. It has a full floor. Is there a pro/con to insulating that space? And we heard from Ed that every inch of your historic home, or any home for that matter, should be insulated and there should be a vapor barrier and you want to keep [brief hesitation]– well, we’re getting a “no” on that. So we shouldn’t have a vapor barrier everywhere I’m getting out of my depth of field so why don’t I turn it over to the experts here? And tell me what do you do in your attic?

[TM] Well, Nick, I don’t want to make my house bigger than I have to make it unless I’m going to live in that area of the house. And the last time I had a substantial attic it was full of my stuff and my wife’s stuff and her father’s stuff. So I wouldn’t go to that attic and say, “I’m going to insulate the roof just so I can keep my storage stuff in a nice place.” I’d put it in my basement. If I didn’t have a basement I would put it in a storage place or hopefully donate it back to useful purpose. So I have to have a valid reason to want to condition the attic. So I only put insulation in the roof when I have to condition that space.

[NR] So if it’s a full walk-in attic with a laid floor and it is just being used for storage , you’re not using that space,  how do you insulate that then?

[TM] I want to insulate the floor I’m walking on. Now I can always take up the floor. And if I can’t take up the floor because it’s too much effort. I can cut holes in the floor and put an insulation in that cavity that is the ceiling joist. If that ceiling joist isn’t deep enough to give me a reasonable R-value, then I can start filling the cavity and then adding more insulation on top of it. Either as a rigid product that I could walk on it protected or as a loose fill. Depends on what I want to do up in that attic. Let’s say I can’t get it greater than, say R-30. And as Ed said, R-30’s a pretty practical area, and if I went from 0 to R-30, I’ve made a significant change in the energy performance of that house.

[NR] So I think the big takeaway is you want to make sure you have a reason to be insulating an attic. Don’t just insulate an attic because you feel like that’s the top of your house and it needs to be insulated. You want to condition the space that you’re living in, not spaces you’re not living in.

[EM] Here’s a way to look at this.

[NR] Okay.

[EM] We used a concept of the thermal envelope. It’s heated on one side. It’s not heated on the other side of the thermal envelope. And your energy bill that comes every month is based on energy lost through every square foot. So the fewer square feet you have, the lower you bill. The more square feet you have, the higher you bill. So if I can look at a space and say, “I want that to be cold,” then I have to insulate my living space away from it, like my floor into a cold basement, or my ceiling into a cold attic. So I have to enclose the heated space completely, all six sides – top, bottom, left, right, back, front – with an airtight and insulated barrier. Does that help?

[NR] Yeah, absolutely. Now, when I was laying this out before, I started getting Ed shaking his head when I used the term ‘vapor barrier.’ Tell me about that. What is a vapor barrier and why wouldn’t you want it everywhere?

[EM] I’d be willing to bet that 99% of the moisture problems that we have seen have been caused by a vapor barrier, because you’re locking moisture into the cavity. You want the wall or the ceiling, whatever it is, you want moisture to be able to move through it, because it’s going to get in there. It’s going to get in from your interior, from the outside. You want it to be able to move, so you don’t want a vapor barrier, as such, in there. So the thermal envelope should be airtight, it should be insulated, and it should prevent the weather from getting in. It should prevent outside water, bulk water we call it. The gutters. The site that you live on all funneling water down into your crawl space. You want the bulk water to get away from the house. But then the vapor barrier becomes less and less important if you do that.

[NR] Is there any good application for a vapor barrier?

[EM] On your crawlspace floor. Your dirt floor.

[NR] So that you’re not getting like a rising dam?

[EM] Right. The moisture you can get- I think it’s 18 gallons for 1,000 square foot crawl space a day. It doesn’t even look wet. It’s just the moisture rising through the floor.

[NR] Well, I think the conversation we’re having right now is kind of moving into an area where we wanted to talk, which is the bad of energy retrofitting. I presume, like a lot of reputable groups, you have been brought in after there has been an attempt made, and you are there to fix things. And so people are spending now double probably because they paid for the first job that didn’t go so well, and now they’re bringing in someone who has their PhD so to speak as we’ve covered before in [laughter] historic homes and energy retrofitting. So what are some of the areas where you would highly recommend people stay away from? What are some of the pitfalls of energy retrofits that you have seen over the years?

[EM] You got one?

[TM] As you started with the crawl space space. Not understanding what you want that space to do. Do you want it inside because there’s a mechanical heating and cooling system down there and ductwork down there? Do you want it outside? And not choosing the right path. Because crawl spaces in our climate are large moisture producers in the wintertime. If we seal a building at the top and forget that the moisture, in some cases a swimming pool below our house, is letting humidity evaporate into that warm house, we are going to have water in places we don’t see. And we are going to see water in places that are obvious to us. Sweaty windows. House just feels wet and smells wet. Those are the first indications of “you did this wrong.”

[NR] So you would say water tends to be the biggest issue, the biggest challenge, the problem.

[TM] Rain hitting our house and moisture inside evaporating in is really what kills our homes. Wood rots and we need to know where the water is coming from and going to.

[TM] I think the most remarkable mistake I ever saw was a log house — a brand new log house. A guy built half a dozen of them in Central Delaware. And we got called to one because brand new house promised to be very energy efficient, and the bills were high. The house was very uncomfortable [laughter]. And you could see the logs on the outside. They had the little notch corners. And you could see the logs on the inside. Very classy. But every corner, the logs had shrunk, and you could see daylight between the logs [laughter]. And you’d just walk your way right up the wall to the 13-foot ceiling. You could see daylight out of every one of those things. You’d turn on the blower door, the fan and it measured– I forget– some phenomenal amount 20 times what I wanted to see in the house. Plus the wood was so old that it met the code for insulation values, and logs like that have about an R1 an inch. And this was a 7-inch thick log, R7. The code was 13 at the time; today it’s 20. So he had a lightly insulated, terribly unsealed house that looked great. It just looked fantastic, but no way.

[NR] The other take away I guess is the worst thing you see is not getting the analysis done. I mean, if you don’t know what you don’t know, you’re never going to be able to fix the problem. So it really does start with a really good analysis and audit of your historic home. So do you have a follow up on that, yeah?

[EM] Yeah, we work on as many new homes as we do on existing homes– homes under construction, and that includes an analysis of what you want to do compared to what maybe would be the ideal, as I mentioned before, or what you can do. So we’ll be approached by a builder who has an interesting idea, and we can show them whether it works or not by an analysis- a numerical analysis. If someone’s building or rehabbing an older home, a historic home even, putting an addition on the back – a lot of them are small, you have to enlarge them- we can get involved with an analysis during the construction or reconstruction of that historic home to help do something in the walls that make sense to add on to it in an interesting way.

[NR] So you could prevent someone from making a mistake with this type kind of work as well. It’s not just looking at “you’ve made your mistakes, now let’s try and figure out how we fix them.” There’s actually a way of doing it in advance.

[EM] Yes.

[NR] I think that’s interesting. I don’t know if a lot of people are aware of that. I think that that’s just like you would go and consult with an architect and an engineer before you put an addition on your historic home, you probably want to go and talk with someone like Energy Services Group to figure out if what you’re doing is going to be an efficient use of that space and if you’re going to have daylight in the nonexistent chinking between your logs, so to speak.

[EM] I have a small builder that I work with in town who just built two houses on the same street a block apart. And about a month ago we had a very light snow. I went out and took some pictures at 7 in the morning before the sun had hit the snow and there was no wind. So the melting patterns on the roof are a great indication of what’s happening in the attic of that house.

[NR] So what can that tell you? If someone goes out and looks at their roof and there’s snow like this, what are you looking for?

[EM] You’re looking for melted snow.

[NR] Okay. And that tells you you have an energy issue.

[EM] Even a layman, you can pick out what’s going on inside the house by the melting pattern of the snow. And this fella, this particular builder, has a way he wants to do stuff. And I’m slowly weaning him and weaning him and weaning him. These two houses- one of them wasn’t done yet and one of them’s four months old- had enormous areas on both of them where the snow had melted. So I showed him the pictures and he said, “We got to talk.” [laughter] I was was hoping we wouldn’t have that problem, but he just did it his way, and it didn’t work out right.

[NR] So let’s talk just briefly about what you have seen as far as changes since you’ve been in this for several decades now. I mean obviously the codes are changing, but has the technology changed as well? Are you seeing different applications? Different things coming online? And are there things we should be looking for in the next 5 to 10 years as well?

[TM] Nick, in the case of the code, it actually caught up to what was learned and studied in the early ’80s. And the process is almost identical.  Today, we are required in the State of Maryland (and a few other states in the nation) that every building will have a performance test at completion: certified that the building’s tight enough, certified that the ducts are tight enough, if the ducts are outside the building envelope, not in the attic, not in the vented crawl space. And that’s the same tool that Ed was starting to use in the early ’80s to diagnose and repair existing buildings. We’ve just fine tuned the process. We know what 30 years more of data to day, “Well, here’s a slightly better way to do it.” Or “Here’s understanding HVAC.” Because a blower door and a duct blaster, another term for the duct-testing device, is identical in its concept. We just put one on the duct system– forced air systems, and we put one on the house. It’s the same technology.

[NR] Now, what about the technology that’s actually used to make the changes? I mean the foams and the rigid boards. Are those getting better? Are they changing quickly, or is it staying pretty static? I mean, what are we seeing there?

[EM] We’re using almost exactly the same materials we used in the early ’80s. Almost exactly. A foam that looks like shaving cream. It comes in a can. We get it in bigger cans than you can buy at Home Depot. And rigid styrofoam to seal over larger holes. Just foaming. Caulk in some place. There’s foam board. There’s rigid styrofoam to cover larger holes, but it’s basically been that for 35 years.

[NR] We’re not expecting to see big changes there. It doesn’t seem like it.

[EM] Just seal the hole the cheapest way you can.

[NR] Okay.

[TM] Fiber glass is fiber glass. We’ve gotten slightly different densities in them. So where we talked about an R-11 batt in my 2′ x 4′ wall, we now put an R-15 batt.

[NR] So it’s getting slightly better that way, but not big changes.

[EM] Correct. And interestingly, the retrofits we do today, we’ll go into someone’s home and tighten it up a little bit and insulate where he hasn’t got insulation. That level of retrofit is — let’s call that Level One. Well, Level Two costs about ten times as much.

[NR] And what’s that?

[EM] Level Two is called a deep retrofit and which you take off the siding on the outside of the house, take out the windows, seal the heck out of the thing, put about two, three, maybe even four inches of rigid foam on the outside of the house, put new siding on, new high-performance windows, and you’ve essentially built what’s a zero-energy house today out of an existing home. That costs about $40,000 as compared to about $4,000 for the conventional retrofit that we do today.

[NR] And obviously, we’re not in love with the idea of taking off your historic windows. We would fight you on that one, and you probably would fight someone in Chestertown on the same thing. But it sounds like you could probably get pretty darn close to zero energy even in a historic home by doing some things.

[EM] You’re never going to get that bill down to the level of a new house. That’s very hard to do especially in a brick home. That’s hard to do unless you’re able to do the gut rehab and build out on the interior. But you can make it considerably more comfortable by cutting drafts down by sealing the house up.

[TM] And Nick, one other area that we never think about. We’ve talked about heat loss and heat gain, energy moving through the building. But as humans, we purchase energy to light our homes, to entertain us, to keep our food, to wash our clothes. This is what we called base load or plug load. And the only way to offset that since we’re going to assume we’re going to use it is we got to make energy. Electricity generally is what we think about doing. And we do it with photovoltaic panels, PV panels up on the roof. Are we going to allow that in a historic retrofit? And that’s the only way we have to offset that energy need with an alternative solution.

[NR] Right. And I know in a lot of historic districts around this state, they either have developed or they’re in the process of developing new guidelines to allow for that because I think that there’s a recognition that we need to have both. That we want to have these historic communities that have this kind of charm and character. But we also don’t want to prevent people from being able to generate those things on site. And so if you can put them on the non-public side, the backward facing roof of a historic structure…I mean, there’s definitely interesting things. And then, obviously, some of it is slick marketing. But we’re even seeing with Tesla and some of these photovoltaic roof systems where it’s actually the shingles themselves are producing things. And I think that that’s one area of technology where, I suspect, we will be seeing big advances in the next 10 to 15 years.

[TM] Ed, why don’t you speak to the P.V. community grid that you developed.

[EM] The state of Maryland is the first state in the union to have what’s called aggregate billing. It used to be, the utilities didn’t want to see solar. They didn’t want the competition from your roof generating some electricity. They were forced to do it. So now they’re forced to do it, what are they going to allow you? Most utilities allowed you to run the meter backwards so that you reduce the energy on a sunny day when you use it overnight when there’s no sun. Every utility’s a little bit different. Some allow you to take that credit. Some will give you a check. Some won’t allow you to take that credit but they always wanted that to be the same meter. Well, in Maryland now I can take a dozen neighbors in my neighborhood, lease an acre of farmland outside of town, put solar cells on the farmland, and utilities require to reduce my bill by my contribution that they got from that separate meter out in the middle of the farm field. They don’t want to do it, but they’re required to do it now. So now we don’t need it on the roof. We just need a group of people to get together and buy some farmland or lease some farmland and do it out there.

[NR] Or maybe not farmland. We like to preserve that around here as well, so maybe we’d find an old desolate parking lot. How about that? Can we settle on that?

[EM] You can do farmland [laughter] and still get 80% of the productivity out of it by spacing it properly.

[NR] Yeah. Interesting.

[TM] But think of Texas. I mean, we’re moving outside of Maryland. But imagine parking your car in Texas on a hot day. Wouldn’t you want some shade?

[NR] Right.

[TM] Sure. Build shade. Put solar panels on the roof and you’re done.

[NR] Well, this has been really fascinating. So we don’t let anyone leave the studio without giving us some insight into their favorite project or their favorite building that they’ve worked on. So we’re going to give you both a crack at this. Whoever wants to go first. Ed?

[EM] I had the great privilege to work in the home of John Dickinson, a signer of the Declaration of Independence and instrumental in writing all of those documents right around the time of the Revolution. It’s just north of Dover; and it’s a beautiful 18th-century home. Two story, big mansion-y looking thing. And we had to get in overnight because it was open as a museum in 10 in the morning. We started at 3 in the morning, two of us in the attic, and we actually heard footsteps walking down the hall below us when we were alone in the house at 4 in the morning. So I remember that for the rest of my life.

[NR] And did you make it more comfortable? More energy efficient?

[EM] I’m told they saved a bunch on the bill but I don’t know if the docents noticed the difference [laughter] in efficiency.

[NR] And, Tom, how about you?

[TM] Nick, I’m enjoying working in Baltimore City working on the early 1900’s homes that are being repurposed. And it’s enjoyable because I know these houses are going to be occupied for 40 or 50 years with new families. Small plug for a builder, Station East is the community and it’s part of the Johns Hopkins redevelopment zone, and it’s really nice to see the city coming back to life. And so now we’re working in a 100-year-old house and making it far more energy efficient than it was when it was originally built.

[NR] Great. Well, it’s been a pleasure to have you both in here. I know it’s answered a lot of questions for me and hopefully for the listener, and we appreciate all that you do to help Marylanders and those beyond the state save some money, make their historic homes a little more comfy, and help our environment out in the process. So thank you both for joining us. If someone wants to get in touch with you, why don’t you give us a plug for Energy Services Group? How do they get a hold of you?

[TM] By the website Phone number 800-908-7000, toll-free. Gets you anywhere in the United States. My e-mail is Thom, spelled T-H-O-M, Ed is

[NR] Awesome. Thank you both for being here with us.

[EM] Thank you, Nick.

[TM] Thanks. Loved it

You don’t need to open a history book to find us and available online from iTunes and their Google Play Store as well as our website: This is PreserveCast.

This podcast was developed under a grant from the National Center for Preservation Technology and Training, a unit of the National Park Service. Its contents are the sole responsibility of Preservation Maryland and the Maryland Milestones Heritage Area and do not necessarily represent the official position or policies of the National Park Service or the National Center for Preservation Technology and Training.

This week’s episode was produced and engineered by Ben and Stephen Israel. Our executive producer is Aaron Marcavitch. Our theme music is performed by the band Pretty Gritty. You can learn more about them at their website:, on Facebook, or on Twitter @PG_PrettyGritty.

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Show Notes

Many older and historic homes are energy efficient, and can be made even more efficient through restoring historic features and completing an energy audit and following those expert recommendations. There are services and incentives throughout Maryland that can guide property owners towards a greener home without altering the historic character of the home. Find out more at: