How to diagnose your high heating bills and drafty home this winter

Part 1: Introduction to Winter Energy Audits

Here in the mid-Atlantic and Northeastern U.S., we’re getting hit by another deep freeze. Those in the center of the country are probably thinking we’re wimps for complaining about single digit temperatures, but hey, it’s all relative. For us, it’s darned cold!

I’ve been getting a number of questions recently, spurred on by the low temps and associated HIGH heating bills. People are asking: “Help! I got my latest heating bill and it’s astronomical. What can I do to reduce it?” or, the other side of that coin is: “Brrr! My family is freezing. I’ve got the heat cranked up but it’s still cold and drafty in some rooms. What can I do make it more comfortable?”

We’re going to walk through a virtual energy audit “live” so you can follow the thought processes and troubleshooting with me. Hopefully, this will allow many of you to go on to diagnose your own issues and end up with a home that is more comfortable, efficient and safe.

Along the way, drop your questions into the comments below the posts, and I’ll do my best to incorporate answers into the article or answer them in the comments.

Let’s get started!

Edit: rather than doing this as one humongous post, I’m going to break each section into a different post. This should make it easier for people to find the pertinent information and step through the process without it getting too overwhelming.

Matt says:

Hi Ted,
We keep getting hammered by the PECO bill, despite doing some things we thought would improve efficiency like new siding, new windows in part of the house and a new roof in the past 2 years. Not to mention a new hot water heater last month. We rank #98 out of 100 similar homes in efficiency, according to PECO. Not good. Apart from replacing more windows, where should we start?

Ted’s reply:

Sometimes those comparisons can be misleading since homes use a variety of energy sources for heat, and PECO only tracks gas and electric. 98th out of 100 is a pretty big red flag, so it does sound like there’s something going on.

When I approach these problems, I like to start by determining just how bad the problem is. PECO has tried to do this giving you that 98/100 number but I don’t trust magic numbers other people come up with, so we’ll do this starting with a blank slate.

An example: High heating costs

My heating costs are much higher than a friend’s down the street. They have basically the same size and style of home. There’s got to be a big problem, right?


Not necessarily! I once had this exact call. Heating bills more than twice as high and the house was a new townhome which should have been very efficient. It turned out, the heating system ran on propane and they were forced to by propane from the association for over $5.00/gallon!!! This was years ago and I bought propane for my home for less than $2.00/gallon.  Same home. Same fuel. But how you buy the fuel can change the heating bill by crazy amounts.

This is the type of thing we want to take into account when doing these comparisons. But it can get “mathy”. How do you compare oil vs. gas vs. propane vs. electric heat pump vs ???

There are some not-so-secret formulas that energy auditors use to compare homes. In a nutshell, what you want to do is figure out how much energy is being used by the home, independent of the fuel. How? Using some really simple math.

Fuel Units BTUs in a unit
Oil Gallons 139,000
Natural gas CCF ~100,000
Liquid propane Gallons 91,330
Propane gas Cubic foot 2,550
Electricity kWh 3,412

Reference: The Engineering Toolbox

What’s a BTU? The Engineering Toolbox – Units of heat

So the first thing we can do to help with our comparison is to convert the home’s energy usage into the universally comparable BTU unit.

This works great if you heat with oil, gas or propane but electricity is more problematic since it’s not immediately obvious how you separate the electricity used for heating from that used to run your lights and appliances. In fact, oil, gas and propane can get confused too because you might heat your water with the same fuel you use to heat your home. We’ll get to this, but let’s dive into that later. Right now, we’re just introducing some of the basics.

For now, assume that we’ve got some magic that allows us to meaningfully come up with a number for heating consumption. Now what?

Let’s do a preliminary assessment

Home and family background:
  • home style (i.e. colonial, rancher..)
  • square footage of heated space (include the basement unless it’s insulated and sealed under the first floor)
  • number of people (i.e. two adults, one infant, one teenager who takes long showers)
Heating system:
  • Heating fuel (i.e natural gas, propane, oil, or with electric heat, like a heat pump or baseboard electric heaters)
  • System type: furnace (which uses heated air), boiler (uses water/steam circulated through radiators or baseboard heaters or radiant tubing in the floor), or electric baseboard heaters.
  • Efficiency, if you know it. I can look it up if you give me the brand and model
  • Typical thermostat setting (i.e. set to 75F all day and night)
Utility bills:
  • Finally, if you don’t mind, share your utility consumption (not cost) for the last year. For the analysis, it’s best to review all the bills for a full year (or more)
  • If you have your own tanks, like for propane or oil, you typically won’t have month to month billing or even year intervals so that gets more complicated. In that case, the more bills we can review, the more accurate the analysis will be.
Any other potentially useful information:
  • For example, if you have a new baby, chances are good that you’ll be using more hot water and keeping the house warmer than in the past
  • If you have other high consumption items, like a hot tub, pool, steam shower, pond, waterfall, etc.
  • There’s an infinite variety of things that can affect energy use. I’ve done these analysis for people who had additional apartments using their energy that they didn’t mention in the assessment. Or a tropical greenhouse that’s kept at 85 degrees during the winter.

That should give us the basic info to get going.

Until next time….


12 thoughts on “How to diagnose your high heating bills and drafty home this winter

  1. I agree that there are several things to look into when figuring out your energy bill. In my opinion, it’s best to hire a professional to come in and do an energy audit because it can help save you money, time, and stress later on. Thanks for sharing your post!

    • I totally agree, getting a local energy auditor in who is independent and experienced at these things is always the first choice. The thing I worry about are the non independent contractors, for example does that work for HVAC companies or builders. You can’t tell whether they’re just trying to sell you something else or being honest.

  2. Hi Ted,

    Same problem as last time, prepared my comments, posted and the re-login response appeared. I’ll try again.

    Thanks for your last post. The Mitsubishi H2i – Hyper Heat Performance unit you recommend is similar in footprint to the Fujitsu wall mount units–microwave size plus units that don’t work in our space oriented smaller home. Our vertical wall ends at 87″ and then slopes up to a 16′ peak. The unit would need to be mounted at an awkward height on a wood tongue and groove wall–aesthetically unattractive with air flowing at an odd height.

    The Fujitsu/Halcyon floor mount unit referenced in my past post was similar to the footprint of our Toyotomi Laser Stove 56 oil stove. Your last post did not include a review of this unit but am guessing your recent “Why I can no longer recommend Fujitsu mini-split heat pumps” may suffice?

    To responsibly reduce my carbon footprint, I’ll need to keep looking for an efficient floor mount heat pump backed by a verified sound warranty and service.

    Suzanne Wood

    • I wonder what’s happening with your logon? Sorry for the problems. I’m just using a generic WordPress setup. Thanks for your patience.

      As for the Fujitsu, I should add that they have subsequently updated their warranty and it’s now supposed to be 5 years. But still, once burned, twice shy as they say.

      Mitsubishi does have a similar wall mount unit but it appears to only be compatible with their multi-headed systems. The unit is model: MFZ-KA18NA. Also, with a large area, using two heads would result in much more even heating of the space by putting one indoor unit at each side of the room. I can’t comment on the price but it may be worth looking into. In that case, you could have plenty of capacity – for example, two smaller 12kBTU systems combined with the MXZ-3B24. The downside? For some reason, the efficiency is notably lower.

      Here’s their floor mount system

      One final thought – you’ve noted that you can’t mount it higher up on the wall due to the configuration of your home. You don’t have to mount these at the ceiling. While it’s the conventional location for it, I had a similar restriction and mounted my wall unit only 16″ off the floor. For heating, it’s actually preferable to have the supplies lower. They’ve historically mounted them high up for air conditioning. Just something to think about.

      • Hi Ted,

        Again, more thanks for your comments. I tried calling a dealer to find out the temperature range for the MFZ-KA18NA because that information is missing from online links I visited. I picked up on your comment, “downside — for some reason, the efficiency is notably lower.” That is a critical concern for us to consider with our hunt for a replacement unit. Additionally, the multi-head system, two floor mount units, would not work for our smaller-sized home.

        The residential heat pump industry is evolving with wider temperature range efficiency, floor mount models being part of the product line, and more consumer reviews versus manufacturer ads.

        Greatly appreciate your identifying product options for consideration.

        Suzanne Wood

  3. Hi Ted,

    Don’t know if this will be a duplicate post … the last “post comment” was followed by a re-login? Anyway, here’s the link for the Fujitsu/Halcyon unit (Page 24) that I failed to include.

    Suzanne Wood

  4. Hi Ted,
    I’ve enjoyed reading your posts. We’ve been looking at air source heat pumps for several years which would replace our faithful Toyostove, purchased in November 1999, which currently heats our 1212 sq ft open concept home with a 16 foot ceiling (one bedroom, one bath, open alcove upstairs) in Petersburg, Alaska. Our house is set amidst conifers and has a full wall of windows on the west side. We occasionally turn on our non-electric Quadrafire propane stove, purchased for use during power outages, when the mercury drops to rare single digit temps.

    The Fujitsu wall mounts you have referenced, although efficient, lack in aesthetics for our wood tongue-in-groove throughout home—too contrasty. However, we’re currently looking at the Fujitsu/Halcyon Extra Low Temperature Heating floor unit, e.g., 15RLFFH. This heat pump is rated for -15F, however, we’re curious where the break is for efficiency.

    Petersburg is set in southeast Alaska’s temperate rain forest where the mercury can occasionally dip to single digit but more normally winter temps are in the high 20’s to low 40’s, summers in the low 60’s to mid-70’s, and an annual average rainfall of 100-130 inches, and snowfall of 150-200 inches. Last couple of years have been abnormal.

    We have Nuheat Comfort Floor electric heated floors, the previously mentioned Quadrafire non-electric propane stove, Venmar HRV, and Toyotomi on demand diesel water heater. Living out the road we use the warehouse roof for water catchment into a 11,000 gallon tank, which is gravity fed to our house.

    Bottom line: do you consider the Fujitsu/Halycon floor mount heat pump as an efficient replacement for our Toyostove based on the above?

    Thank you,
    Suzanne Wood

    • Oops, I keep trying to reply to your question and losing it so I’ll keep this short!
      That Fujitsu you reference sounds like a super version of the ones I use. And the new floor / low profile system looks pretty nice! Wish they had that when I installed mine.
      I’m not seeing specs on the unit that you mention. The only combinations that come up on their website that I can find are the low temperature unit with conventional wall unit. If you can point me to where you’ve found more info, I might be able to comment on that particular unit.
      However, in general, they do quite well with these units as far as holding efficiency as the temperature drops. Since the low temperature units use extra large outdoor heat exchangers, they’re more efficient under normal operating temperatures, which is great because that means that 90% of the time, you’ll be running in a very efficient range for the system.

      My biggest concern would be capacity. That Toyostove you’ve got can crank out a lot more BTUs than can the heat pump. I’d be hesitant to recommend switching without knowing more about the specific Toyostove because the last thing you want is to invest in an expensive new heater to find that it doesn’t have the capacity to heat your home. In fact, back of the envelope, a 15kBTUheater like the Fujitsu seems quite undersized for your home. But again, I’d have to know more about your Toyostove.

      Often, in situations like yours, I think “if it ain’t broke…” so my inclination might be to just replace the Toyostove with another similar unit unless there’s a really compelling reason to switch to a new technology.

      A final consideration, I’m starting to have concerns about the reliability of the Fujitsu. I had to replace all of my units a couple years ago due to a big power surge that killed a fair amount of electronics in my neighborhood. That I can forgive. But this winter, the main unit in my living room has been out for a couple months(!). Fujitsu reneged on their promise to replace the defective wall unit and I’m on the hook for an entirely new sysetm. This really rubs me the wrong way, even though it’s standard practice and written into the warranty, but why should I have to pay anything to replace a unit that was clearly defective? (coils leaking and temperature sensor died just one month out of their 2-year warranty). Because of this, I have a very hard time recommending them anymore.

      • Hi Ted,

        Thank you very much for your comments–appreciate it’s difficult to theorize about these scenarios site unseen. Here’s a link to the unit in question, specifically on Page 24. It details the three sizes 9, 12 and 15,000 BTU systems.

        Our Toyostove is a Laser 56, 93% heater efficiency, heat rating: 8 (low), 15 (medium), 22,000 (high) BTU/h; typical room size: 920 sq.ft. (0F – 24 BTU/hr), 1100 sq.ft. (20F – 20 BTU/hr).

        The idea for considering an air source heat pump started with trying to reduce our carbon footprint.

        Suzanne Wood

      • There’s definitely something to be said about reducing the use of combustion systems. I’ve mostly switched over to heat pumps to get away from using so much heating oil too, so I empathize with your goals.
        Back to your stove. That’s a great little Toyostove, sounds excellent. The nice thing is, since it has the three settings, you know what your usage has been like over the years. How much do you run it on the ‘high’ setting? If you run it at high very much, I don’t think the small heat pump will satisfy your heating demands since it’s going to be running at diminished output at the coldest temperatures. At more moderate temps, it appears that it would do the job, though it will be pushing hard to maintain that 15+ kBTU output. My mini-split systems are happiest running at half output, just purring along steadily.

        Looking at the specs, the HSPF of those Fujitsu low temperature units is excellent – 11 to 12+.
        From a consumption perspective, I can tell you about my experience this winter. I have a dedicated 12RLS unit (the older super-high efficiency system) in my half-exposed basement. During our cold weather, it’s been running about 30-40kWh/day to keep the basement at about 68F. Basements are pretty easy to condition, but the main take-home is the consumption. Running pretty hard, it’s been using that much energy. If you’re using the slightly more efficient systems as your primary heating, I’d estimate you’d be looking at closer to 40-60kWh/day. Clearly these are “shoot from the hip” kind of numbers.

        You might find my home’s energy monitor to be interesting. Note that my living room system is currently dead. Also, our stupid hot tub is sucking enough power to power a small home 😦

        I would also seriously consider one of the Mitsubishi Hyper-heating models. They claim excellent low temperature efficiency and output: “H2i – Hyper Heat Performance offers full capacity heating at 5°F (9 & 12kBTU) and 73% capacity at -13°F (18kBTU).”
        This sounds like just the ticket. I’d look at that 18kBTU unit. With variable speed heat pumps, you really want to oversize to give you the headroom to handle the cold and not work so hard at moderate temperatures. The caveat is that the 18kBTU is slightly less efficient. However, that can be deceiving. When it runs at a smaller fraction of it’s rated output, then the efficiency will increase. Frankly, I’m looking at replacing my defective Fujitsu units in my living room with one of these, all things considered.

        For others interested in the Fujitsu literature, here’s their link:
        Fujitsu Halcyon brochure

        Here’s the Mitsubishi page:
        Mitsubishi mini-split heat pumps

        Mitsubishi mini-split 2014 consumer brochure
        This PDF covers their larger, multi-headed systems. Not appropriate for your use but others may find this interesting for whole-house applications.
        larger, multi-headed systems

  5. Hi Ted,
    Colonial 3,300 square feet. 3 adults one child. 2 Electric Heat Pumps: Large one in basement is Payne, Model Number PF1MNB048; Smaller one in mud room for rooms above garage has no name. Just has large number SA11694 and Model Number BCS2M18C00NA1P-1. Thermostat at 72 now and 70 in summer. Consumption Feb 2013 through Jan 2014 – kWh 5800, 4530, 2815, 1684, 1533, 2346, 1334, 1568, 1719, 3023, 5833, 7349
    Thank you,Matt

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