We tuneup our bikes and cars, get periodic physical exams for ourselves, but do we ever think of optimizing the systems in our house that keep us comfortable? After a recent purchase of a rental property, our Green Designee REALTOR Keith Parsons connected us with building performance analyst Scott Sidlow. Immediately following settlement, while the house was still empty, Scott performed a building efficiency assessment. 

By this time next year, we expect to cut our energy bills by about 18%, and the carbon footprint by about 22%, while still keeping the gas furnace & water heater

You may ask… what is a building performance analyst? Per the national nonprofit Building Performance Institute, this person conducts on-site inspections and tests to assess the energy efficiency of homes. They do this by measuring leakage from ducts, as well as leakage from the whole house (doors, windows, attic, basement).

The analysis and report was well worth the $300 that Scott charges. We plan to implement many of the recommendations this fall. By this time next year, we expect to cut our energy bills by about 18%, and the carbon footprint by about 22%, while still keeping the gas furnace & water heater. This should also make this house more comfortable and less drafty. Following are the specifics of what we learned about this 910 square foot, 68 year old house in Abington Township, Montgomery County, Pennsylvania. 

Image credit: bpihomeowner.org

The first thing Scott Sidlow did was to measure the exterior footprint of the house. Next, he inspected the entire home inside and out and assessed the major appliances. Eventually, he setup the blower door. The blower door test involved closing all windows, bringing the home up to a higher than normal  pressure (of 50 pascals) and then measuring how much air was leaking out.  We learned to check for drafts by each window using the backs of our hands. Scott pointed out various other issues with the house, mainly from an energy and safety perspective. Though I tried to take notes, I was relieved to get a written report from Scott a few days later. 

We learned about air changes per hour at 50 pascals of pressure (ACH50). The blower door test showed Scott that this house has 13.39 ACH50. In comparison, the Pennsylvania code for new houses is much tighter at 5 ACH50. The blower door test showed an effective leakage area (ELA) of 89 square inches, which works out to 0.62 square feet (89 / 144). Both of these tell us that this house is leaky

To avoid mold in bathrooms and kitchens, typically mechanical ventilation (fans) is recommended. In addition, for homes that have been air sealed below 5 ACH50 (more tight) the recommendation is that mechanical ventilation be provided on a continuous basis to provide sufficient fresh air for the occupants. I translate this to mean that we could hold off on continuous mechanical ventilation until we seal some of the drafts!

Image credit: Scott Sidlow

I had heard about the Home Energy Rating System (HERS), an index to measure a home’s energy efficiency. Average new homes get a HERS score of 100. Zero energy homes get a HERS score of zero. This specific home has a HERS score of 102 without solar, and a score of 74 with the currently installed solar panels. 

The report showed that the family living here would emit 5.4 tons of CO2 annually, split between heating, cooling, water heating and lights & appliances. Our worldwide goal is 2 tons of CO2 per person, which would include emissions not just from the housing but also transportation and food. 

I noticed the top two figures (meaning the most emissions) were from heating this house and from the lights & appliances used (3.0 and 2.5 tons respectively).

In an effort to reduce emissions from this house, during year one we will likely work on the recommendations for lighting & appliances first, and then improvements like air sealing and insulation to reduce the heating bill. 

Below, we’ve listed observations from the report as a sampling of what you should look for in your house. Of course, you could always contact Scott! 

Heating this house emits 3.0 tons of CO2 per year. 

The gas furnace is one made by Lennox with 93% annual fuel utilization efficiency (AFUE). We asked how Scott knew this just by peeking into the utility closet, and he pointed to the exhaust pipes from the furnace, which were PVC pipes going into the attic and out the back of the house. Notably, not to the chimney. As he opened the access panel to the furnace, the sticker inside confirmed his assessment when we saw 44,000 BTU/hour input, 41,000 BTU/hour output, which works out to 93% efficiency (41000 divided by 44000).

These are also known as high-efficiency condensing furnaces, furnaces that don’t push their emissions up the chimney. Instead, their output is warm air and water vapor via PVC pipes along the side of the house. This is 93% efficiency, so likely as good as we can get with a gas furnace. Eventually, we would replace this with an electric heat pump to reduce our emissions.

Thermostat — We have a basic thermostat which would be replaced with a programmable thermostat, or perhaps a “smart” thermostat that learns the household’s routines via built in motion sensors. Regardless, we would definitely program it to drop the wintertime temperatures when no one is expected to be home, and during the nights. 

Air sealing and insulation — We remembered that Scott had mentioned the house is quite leaky and would feel drafty in the winter. Whether we heat with gas or electric, in the end, it’s all about the comfort.

Because most of the air sealing work is in the attic and it being mid-August and quite hot right now, we would delay the tasks below until fall’s cooler days but before the start of heating season in November. We’ll try to do what we can ourselves, and then call in outside contractors, knowing that within a year or two, we would also be saving money on the gas bills.

Some of the action items listed on Scott’s report are — air sealing the attic, increased insulation in the attic, insulate wall between unheated storage room and house, correct issues with insufficient duct return system, correct issue with kinked duct to main bedroom, seal ducts, clean ducts. You get the idea. 

Lights & appliances for this house will emit 2.5 tons CO2 per year 

It seems many of the bulbs were still incandescent. These seem easy enough to swap out with LED bulbs. If we’d gotten a PECO home energy assessment, we would have gotten all new LED bulbs; well worth the $49 cost. For this house, we will likely replace the bulbs ourselves, or ask our tenant to. 

The report pointed out an improper electrical connection in rear bedroom — This is a safety issue that needs to be handled within the first month.

The cooking range is powered by gas, is functional but rusty. It will likely be replaced with an electric cooking range.

The clothes washing machine is a well used front loading unit. It will likely be replaced by a similar unit when it fails.

The clothes dryer is powered by gas, and venting inside the house due to broken dryer vent. For now, the vent has been replaced. This unit will likely be replaced by an electric dryer, and supplemented by a clothesline in the back yard.

The refrigerator was manufactured in 2020 and will remain.

The dishwasher may be used infrequently, or replaced with additional storage. 

Water heating for this house emits 1.0 tons CO2 per year 

The water heater here is made by Rheem, storing 40 gallons of hot water heated by fracked gas. We were told it is 62% efficient and manufactured in 2016. Interestingly, this was the only appliance now venting up the chimney. When it’s time to replace this, the report suggests we replace it with an electric heat pump water heater. We may instead replace with a tankless electric water heater, which would free up space in the tiny utility closet, and not keep water hot 24 hours a day.

The report pointed out an improperly sealed furnace flue. This is a safety issue that needs to be handled within the first month. 

Cooling this house emits 0.9 tons CO2 per year 

The electric central air conditioning system is also made by Lennox, with a seasonal energy efficiency ratio (SEER) of 13, manufactured in 2012. This is a minimally efficient system that we’ll try to use as little as possible, and someday, remove when we replace the gas furnace with an electric heat pump that heats and cools the interior.

To reduce the emissions, we could decide to use this system only on extreme hot days, and when someone was home.

We’ve already noticed that the ceiling fan in the living room keeps this space quite comfortable; we could invest in ceiling fans in the bedrooms as well, adding to comfort with a lot less electricity used. The rooms already have heavy curtains to block the summertime sun.

By the time I’ve refined this post, I’ve noticed that the current resident has chosen not to use the cooling system. So maybe we’ve saved 0.9 tons just by a lifestyle choice. 

Photovoltaics (solar panels) reduce our emissions by 2.0 tons CO2 per year 

Though this house has a rooftop photovoltaic system, it seems to be just a 3.36 kW system. Since we plan to eventually electrify everything (furnace, water heater, dryer and stove), we’ll eventually need more emissions-free electricity and hardly any gas. We’ve noticed that there is much more space available on this roof, and intend to pack it with solar panels. If more electricity is needed, we’ll of course buy it from our utility and continue pushing that they transition all their generation away from coal, oil, gas and nuclear to renewables like wind and solar. 

Service charge 

Though there are no emissions from service charges, there is a fixed monthly cost from the electric and gas utility. These service charges work out to about $300 annually. If we were to completely replace our gas appliances, we could halve this cost. 

In conclusion…

Note that none of these problems were pointed out by the home inspector, who was contracted before we purchased the house. 

What Scott would like ideally is to work with insulation and HVAC people so that houses in Southeast PA use the least energy and offer the most comfort. What Meenal would like is for someone to use Scott’s report and complete the jobs; otherwise, it’s just another nice report.

If you have an insulation or HVAC company you recommend, please connect them with Scott Sidlow and myself. If you seek the services of a realtor, I would recommend Keith Parsons. 


  • Meenal Raval — meenal.raval@gmail.com
  • Scott Sidlow, Solstice Properties — scottsidlow1@gmail.com 
  • Keith Parsons, Keller Williams Real Estate — keith.parsons@kw.com

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