Energy Audit: 1970s Townhouse in Columbia
A comprehensive energy audit revealed attic insulation gaps, significant air leakage, uninsulated rim joists, and more — all common issues in Howard County townhouses from this era.
The Home at a Glance
This 1970s townhouse in Columbia, MD is representative of thousands of similar homes built across Howard County during the era's housing boom. Like many homes of this vintage, it was built to the energy standards of the time — which fall well short of today's codes.
The homeowner scheduled a $100 Energy Audit to understand why energy bills felt high and to learn what improvements would make the biggest difference.
- 1970s construction
- Townhouse style
- Columbia, MD
- BGE utility territory
- Partial finished basement
- 11.77 ACH50 (blower door)
What the Energy Audit Revealed
Our blower door test and thermal inspection identified seven key issues driving energy loss in this home.
Low Attic Insulation
The attic had significantly less insulation than current energy code calls for. In a 1970s townhouse like this, it's common to find just a few inches of original insulation — far below the R-49 recommended for Maryland attics. Inadequate attic insulation is one of the biggest drivers of heat loss in winter and heat gain in summer.
Attic Insulation
Leaky Building Envelope
The blower door test told the story: this home measured 11.77 ACH50 — nearly four times leakier than the 3.0 ACH50 standard for new construction. Air leaks throughout the building envelope — around penetrations, at framing connections, and through unsealed gaps — were allowing heated and cooled air to escape while letting unconditioned outdoor air in. Air sealing is the most cost-effective energy improvement for a home like this.
Air Sealing
Uninsulated Rim Joist in Basement
The rim joist — where the house framing sits on top of the foundation wall — was uninsulated throughout the basement. This is one of the most overlooked sources of energy loss in homes like this. In the unfinished section, the rim joist was completely exposed. In the finished section, drop ceiling panels concealed it from view. The good news: those panels can be temporarily removed to access the rim joist for insulation and air sealing, then replaced when the work is done — so we can treat the entire basement perimeter without permanent disruption to the finished space.
Rim Joist
No Bathroom Exhaust Fans
This home had no bathroom exhaust fans installed — a common omission in 1970s construction. Without mechanical exhaust, moisture from showers has no way to leave the home efficiently. We recommended installing bath fans to control humidity, prevent mold growth, and improve indoor air quality. This is especially important once the home is air sealed, as a tighter envelope needs proper ventilation.
Ventilation
Unsealed Gap at Air Handler Coolant Line
Where the refrigerant line penetrates through the air handler cabinet, there was an unsealed gap allowing conditioned air to escape from the system. This is the kind of issue that quietly wastes energy and is easy to miss without a thorough inspection. The fix is straightforward: sealing the gap with putty to keep cooled and heated air flowing where it should — into the living space, not out through equipment gaps.
HVAC Sealing
Two Unlocked Windows
During the audit, we found two windows that were unlocked. When a window isn't fully latched, the sash doesn't press tight against the weatherstripping — creating a gap that lets conditioned air pour out and outdoor air flood in. This showed up during the blower door test as excessive air leakage. It's a simple fix — just locking the windows — but it's one of those things that's easy to overlook and can meaningfully impact comfort and energy bills.
Windows
20-Year-Old Furnace Needs Inspection
The home's furnace is approximately 20 years old. While that doesn't automatically mean it needs to be replaced, a furnace of this age should be professionally inspected to make sure it's operating safely and efficiently. We recommended the homeowner take advantage of BGE's free HVAC tune-up program to have a qualified technician evaluate the system. An expert can assess its condition and help the homeowner make an informed decision about maintenance or future planning.
FurnaceOur Recommendations
Attic Air Sealing & Insulation
Seal air leaks in the attic floor, then blow in insulation to bring the attic up to the recommended R-49 level. This combination addresses both of the top energy issues found in the audit.
Rim Joist Insulation & Air Sealing
Insulate and air seal the rim joist around the entire basement perimeter — including the finished section accessible through the drop ceiling panels.
Bathroom Exhaust Fan Installation
Install bathroom exhaust fans to manage moisture and maintain healthy indoor air quality, especially after air sealing tightens the building envelope.
Seal Air Handler Coolant Line Gap
Use putty to seal the gap where the refrigerant line penetrates the air handler cabinet, preventing conditioned air from escaping the system.
Lock All Windows
Latch the two unlocked windows to ensure proper contact with weatherstripping and eliminate the unnecessary air leakage found during the blower door test.
Furnace Inspection
Schedule a professional inspection of the 20-year-old furnace through BGE's free HVAC tune-up program to ensure safe, efficient operation and get an expert assessment of the system's condition.
This Homeowner Qualified for $4,659.73 in BGE Rebates
Columbia is in BGE utility territory. Through the Home Performance with ENERGY STAR program, this homeowner qualified for $4,659.73 in rebates toward their insulation and air sealing improvements.
Rebates typically range from $600 to $4,500, but can go higher depending on the scope of work and projected energy savings. Your $100 Energy Audit is the first step to qualifying.
Frequently Asked Questions
What energy problems are common in 1970s townhouses in Columbia, MD?
1970s townhouses in Columbia commonly have insufficient attic insulation (often below current code), significant air leakage throughout the building envelope, uninsulated rim joists in basements, and missing bathroom exhaust fans. These issues lead to higher energy bills, uneven temperatures, and moisture concerns.
Can you insulate rim joists in a finished basement?
Yes. In finished basements with drop ceiling panels, the panels can be temporarily removed to access the rim joist area for insulation and air sealing. Once the work is complete, the ceiling panels are replaced. This is a common approach in Columbia townhouses with partially finished basements.
How much do BGE rebates cover for insulation work in Columbia?
BGE rebates typically range from $600 to $4,500 for insulation and air sealing work through the Home Performance with ENERGY STAR program, though they can go higher — the homeowner in this case study qualified for $4,659.73. The exact amount depends on the scope of work and projected energy savings. A $100 energy audit is the first step to qualifying for these rebates.
Why does my townhouse need bathroom exhaust fans?
Bathroom exhaust fans remove moisture generated by showers and baths. Without them, excess humidity can lead to mold growth, peeling paint, and wood rot. Many 1970s-era townhouses were built without exhaust fans. Installing them is especially important after air sealing, since a tighter building envelope needs proper mechanical ventilation.
Live in Columbia? Let's Find Your Savings.
A $100 Energy Audit is the first step toward a more comfortable, efficient home — and qualifying for BGE rebates.
Book Your $100 Energy AuditOr call 443-690-8233 · [email protected]