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Case Study: 1895 Historic Claremont Home

Before the Assessment:Home Retrofit Project Claremont

This two-story, 2,200–square-foot house on a raised foundation had a mixture of new and original features: wood siding; wood single- and double-paned windows; lathe and plaster walls as well as drywall; knob and tube wiring in the attic; package heater and A/C units on the first and second floors; and floor supply ducts/vents downstairs with ceiling supply ducts/vents upstairs. The homeowners complained that their kitchen had no supply duct and was hot in the summer and cold in the winter. It was hard to heat and cool the upstairs areas, and that the upstairs bathroom and dressing room had no supply ducts.

What the Energy Assessment found:

The homeowner "learned think in terms of the whole system, rather than room by room. We learned a lot about the advantages of having the house insulated rather than trying to direct the energy to specific areas." The house had low attic insulation; poorly insulated ducts; a leaky building envelope; an old (1992), wasteful furnace/AC and duct system downstairs; and no air sealing at the wall penetrations that allowed hot/cold air into the building envelope.

What was suggested:

Based on the results of the audit, the home performance contractor gave the homeowners every option so they could choose what was in their best interest and budget. The audit results suggested: Install a smaller A/C system; replace all ducting with new R-8 ducting; bury ducts with blown-in insulation; insulate all sheet-metal boots; seal the crawl space; add insulation to the walls; and conduct a lighting and electrical baseload evaluation.

Retrofit highlights:

The crawlspace was sealed and a vapor barrier installed to reduce moisture and air infiltration into the home. The downstairs heating/cooling unit was replaced with a hydronic heating unit and new ducting in the crawlspace, with a smaller A/C placed outside the house. The contractor created a custom sheet-metal boot that allowed them to add a high-performance duct system without cutting into the 100-year-old wood floor for smaller floor vents. New ducting/floor vents were added in the kitchen. In the attic, the remaining knob and tube wiring was removed so blown-in insulation could be safely added to achieve R-38. The heating/AC package unit upstairs was newer (2003), so it was retained and new ducting and plenum were added to improve its efficiency. The upstairs dressing room had a flat roof and no space for ducting, so a customized solution included insulating the flat ceiling and installing specialized exterior ducting to the room. All attic penetrations were air-sealed. Insulation was added to exterior walls through the wood siding; after patching and painting no evidence of the holes remain. The water heater was moved outside of the home to improve safety.

Homeowner comment:

"This house is one of the oldest houses in Claremont. It was built in 1895. We've lived here for over 30 years and plan to keep it for longer. It's been a challenge to modernize the house, and I think that we've achieved that by comprehensive insulating, wall sealing, and a new system for heating and cooling."

The results:

  Before Retrofit After Retrofit
House Air Leakage 6638 CFM50 3772 CFM50
AC Size 3 Tons 1.5 Tons
Heater Size 80,000 BTUs 24,000 BTUs
Wall Insulation R-3 R-13
Duct Insulation R-1 R-8


  Before Retrofit After Retrofit
AC Size 2 Tons 2 Tons
Heater Size 40,000 BTUs 40,000 BTUs
Attic Insulation R-11 R-38
Wall Insulation R-3 R-13
Duct Insulation R-4.2 R-8