New Haven Home Energy Audit: 111 Years Old


I gathered up my auditing equipment and headed off to a neighboring community to perform a home energy audit on a home that was constructed in 1901. Before I head out of the office and leave the comfort of my desk computer, I look up the home through County Records to determine about what year the home was constructed, about how big the home is, and if records show any remodel years.

When records indicate construction in 1901, I know that I will be dealing with a very old home that has had some degree of care over the years or it wouldn’t even be standing. I know that the home was originally heated with a wood fireplace or two and that some sort of up-dated heating source has been added. Also, I’m guessing if the foundation has not been replaced, the foundation is going to be a little shaky.

This home energy audit was a team effort. We took two vehicles, my partner would carry the equipment in one rig and I would meet him there in another rig. This way, since it is Friday afternoon, I can take a short cut home after the audit.

The husband has taken off work early to be here during the home energy audit. The gentleman of the house arrives and my partner finally shows up with the equipment. The first order of business is to ask the homeowner to take us on a tour of the house.

Remodel and additions

  • The homeowner does not know for sure, but I suspect this home has been added onto twice. Looks like a back porch area was added as living space at some point and then an addition with a master bedroom and bath was added on behind the porch.
  • The whole interior of the house has under gone major upgrades. Standing in the kitchen on the wood laminate flooring, looking at the granite counter tops and all stainless steel appliances, one would not suspect this home has been here for 111 years.
  • The interior walls have been replaced with drywall and freshly painted. The exterior walls have been replaced with t1-11 and also freshly painted.

Electrical system

  • The attic still has signs of the original knob and tube electrical wiring. Today, the electrical system has all been upgraded to romex wiring and a grounded, 200 amp circuit breaker panel. All electric outlets, light switches, and fixtures have been replaced.

Plumbing System

  • Water fixtures and faucets have all been upgraded recently. The old iron pipes remain and seem to carry plenty of water pressure. A modern gas water heater sits in the utility room closet next to the furnace.

Heating system

  • In the old part of the house, both supply and return heating ducts are in the floor. In the master bedroom addition, both are in the ceiling. A 90% efficient gas furnace sits with the water heater in the utility room closet. There is no air conditioning.


  • The underfloor of the main house has black visqueen attached to the bottom of the floor joist. However, only about 50% of the floor has fiberglass batt insulation. The newer addition with the master bedroom and bath has no floor insulation.
  • R-13 batt insulation was added to the exterior walls when the exterior siding was replaced. The infrared camera tells me there is a few small areas that were missed.
  • The upstairs has two unfinished rooms – at least they are unfinished at this time and the roof trusses are exposed. The homeowner tells us that this was his bedroom when he was growing up. The homeowner is in the process of remodeling the upstairs and has removed all the interior wall covering. Insulation was never added to this part of the home.

Windows and Doors

  • Doors and windows have been replaced. The front door is metal with 1/2 glass and a storm door. The utility room door is metal and the master bedroom has a vinyl framed, double glass, sliding door.
  • All the windows have been upgraded to vinyl framed, double glass units. I suspect U-35 with some Low-E glazing.

Homeowner Concerns and Wish List

The homeowner would like to use their available weatherization funds to help insulate the upstairs remodeling project. By using the funds to install the insulation, their remodeling budget can be spent on drywall and floor coverings.

Also of concern to the homeowners is the cool spots in the living room and the warm spot in the master bedroom. The living room has two supply registers located near interior walls and two return registers located under the living room windows. They find that there is noticeable cool air that comes out of the return registers, so they have placed the dogs sleeping mat over on of them and a fluffy pillow over the other.

Because of the cool air that rises from the return registers, they have effectively closed them off. The only working return air register is in the master bedroom. I asked them why the return air grill in the ceiling of the bedroom was dented and was informed that the register would rattle when the furnace was on so he struck it with his hand until it stopped rattling.

The Blower Door and Air Infiltration

  1. First blower door test is with all interior doors open.Blower door was set up in the front door opening and the house was prepared for the test. With all interior doors open, the air leakage was 4,100 CFM ( cubic feet per minute ). I believe for this home, this represents around 9 air changes per hour.
  2. Second test is with the door at the top of the stairs taped off. This takes the upstairs air leakage out of the equation. However, there is leakage from the recessed lights in the kitchen, bathroom, and hallway which means the downstairs is still connected, air leakage wise, to the upstairs. Second leakage test was 3,200 CFM.
  3. Third test was done after the ducts were taped off in preparation for the duct blaster. This should eliminate duct leakage from the overall house air leakage figure – this reduced the house leakage to 2,300 CFM.By eliminating both the upstairs and the heating ducts from the air leakage, the home is at about 4.5 air changes per hour.

The Duct Blaster and Heating Duct Leakage

The duct blaster fan is placed over one of the return air grills in the living room and the rest of the supply and return registers are taped off. The fan is cranked up and air is forced into the ducts. In this case, air leaks out of the ducts as fast as the fan can put air in. The ducts are so leaky, no reading is possible.

More About This Home Energy Audit and Heating Ducts

A sign of things to come was visible while we were taping of the return air registers in the living room. The return air ducts were formed by attaching sheet metal to the bottom of the floor joists. By removing the register, you can see that the metal has become very rusty and has rusted through. I can look through the rusty hole and see the crawl space below. No wonder the duct leakage is so much.

There is decent head room in the crawl space. In the normal confusion of leaving the office, I have forgotten my coveralls, boots, masks, and head light. Oh well, the show must go on – at least I have a flashlight.

The heating ducts under the old part of the house

  • The return air ducts.As I mentioned earlier, the return ducts are formed by attaching sheet metal to the bottom of a couple floor joist. In several places, I can see where time and rust has caused the sheet metal to fail leaving very noticeable holes. The largest holes are directly under the floor registers.
  • The supply heating ducts.The supply ducts are 6 inch round metal ducts wrapped in asbestos. They attach to a central metal plenum that is located directly under the furnace.

How to decide on the best energy saving measures

As we begin to remove the tape from the registers and put away the blower door, my partner and I begin to discuss with the homeowner how can you conserve energy in this 111 year old home.

Factors of Conserving Energy

  1. What is the most cost-effective energy saving measure?
  2. How much money is available to spend on energy saving measures right now and how much might be available in the future?
  3. Which energy saving measures need to be done by a contractor and what can be a do-it-yourself project?
  4. Are any of the energy saving measure directly or indirectly connected to home safety.
  5. Are some energy saving measures more connected to home comfort than others?

What should be done to save energy as a result of this home energy audit?

The audit of this home has provided valuable information concerning what needs to be done with this home to save energy. Without the audit and the data provided by the blower door and the duct blaster, the acute failure of the heating duct system would not of been realized by the homeowner.

  1. Uncover return air supply registers – Do not cover the two return air registers in the living room. This restricts the flow of air back to the furnace and causes the air flow to be out of balance. In affect, the furnace is starving for air which increases the energy needed to heat the home. No cost associated with removing the doggie bed from the top of the register.
  2. Air seal heating supply and return plenum – From underneath the home, open up the heating plenum that is under the furnace and air seal all connections and joints with duct mastic. Mastic, gloves and labor, $65
  3. Install a new return air register and duct – Increase the size of the supply register that is located next to the interior wall in the living room and make it a larger return air register. Connect this register to the return air plenum connected to the furnace.Now the return air register is located in the center of the home. Estimated cost $300
  4. Install two new supply registers – The two return air registers that are located under the windows need to be connected as supply registers. To keep from cutting new holes in the floor, have a sheet metal contractor build two new supply boots to be placed in the current floor cutouts. Connect these new boots to the supply plenum that is located at the furnace. Estimated cost $600
  5. Replace all supply ducts in the old part of the home – Carefully remove and bag the asbestos covering that is around the old metal ducts. I believe the homeowner can do this himself, otherwise a licensed Asbestos Remediation Contractor will need to be used. Need to check your local jurisdiction concerning the procedures for removing asbestos.Replace all old metal supply ducts with new duct material. Flex duct is good and so is appropriately air sealed metal ducts. If using round metal ducts, wrap with insulation according to local building codes. Estimated cost $800
  6. Insulate the attic – Install a 2×2 furring strip to the exposed 2×4 roof rafters. This will increase the depth of the rafter space and allow for the installation of high density fiberglass R-21 insulation batts. Before installing the insulation, air seal the cavities.If funds are available, this is an ideal application for using spray foam insulation.

    Estimated cost with fiberglass, including 2×2 furring, $1,800. Estimated cost using spray foam, $4,000.

  7. Insulate the floor – Remove the black visqueen from the bottom of the floor joists. Air seal the floor with insulating spray foam. Install high density R-25 fiberglass batts. Install an air barrier to the bottom of the floor joists like Typar or Tyvek house wrap.

This article serves as an example of a New Haven home energy audit. We ensure you are aware of all that needs to be done with a thorough home energy audit.






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