General Information

Building Name: Residence

Building Location:             City: Manchester            State:            NH            Country: Hillsborough

Project Size: 1040 sqft

Building Type(s):  Typical One and ½ Story Cape

Project Type: Insulation and Weatherization

Building Architect/Project Team: Energy Audits Unltd, LLC

Description

This project consisted of a Single Family Home located in Manchester, NH.  J. Roy Builders, who built almost 75% of the homes in this neighborhood, built the home in1952.  The accepted insulation material at that time was 1-inch thick fiberglass batt.  This material was installed in all the sidewalls, up along the roof slopes, being supported by cardboard sheets tacked to the underside of the roof rafters, and finally laid across the second floor bedroom (finished attic) ceilings.  Some energy saving measures had already been installed in the home.  These measures included a setback, digital, programmable thermostat, a gas-fired flow-initiated hot water heater, some compact fluorescent lamps (CFLs), with the clothes washer, dryer, and dishwasher having been replaced with Energy Star rated appliances.  There was also a whole house humidifier tied into the return air of the oil-fired forced hot air furnace.  The auditor conducted a Home Energy Audit on the home during the summer of 2005, utilizing diagnostic tools available at the time.  These tools included a Minneapolis Blower Door, an Infrared thermal imaging camera, a TI-86 graphing calculator, and Fyrite Pro 125 Combustion Tester.  The specific functions of these tools are described below in the Information and Tools section. 

So the results of this project are based almost solely on the addition of insulation and air infiltration reduction.

Overall Project Goal/Philosophy:  To reduce overall energy consumption while maintaining a comfortable and healthy indoor air quality environment.

Secure/Safe Goal: DO NO HARM.  Health and Safety issues are addressed without creating new ones.  The structure of the building is sufficient to support the additional weight of the insulation.

Sustainable Goal: To install weatherization measures that do not require further maintenance, with the possible exception of changing light bulbs after 7-10 years, the lifetime of today’s typical Compact Fluorescent Lamps (CFLs), the replacement of air and humidifier filters, and the yearly tune-up of the furnace and central AC.

Functional Goal: To decrease the building’s overall use of fossil fuels, either directly, such as with Oil and Natural Gas delivered to the home, or indirectly, such as Electricity having been generated from the consumption of fossil fuels by the utility.

Aesthetic Goal: The installation of weatherization measures should be done in a workmanlike manner that will not significantly affect the current lifestyle in the home.

Cost-Effective Goal:  Install weatherization measures, which have product life cycles, that assure the projected Savings to Investment Ratio (SIR) and reasonable Return on Investment (ROI) are met.

Process

Overview of Process:  An interview is conducted with the primary contact person, during which general information is gathered such as the age of the building, the number of occupants, approximate ages of the occupants, and lifestyle.   Then, the home is measured for square area and the number and types of doors and windows is noted.  Further auditing activities will include determining what type of insulation exists, if any, in the walls and attic, testing the furnace for combustion efficiency, noting the make and model of the Domestic Water Heater (DWH), testing for CO levels in the living space, and determining what type of heating / cooling controls are in place.  Finally, the home is depressurized using the blower door that exaggerates the exfiltration rate of the home.

The measures installed included a dense-pack cellulose pumped into all side walls, slopes, first floor cold ceiling, and knee-walls.  The second floor stairway ceiling was dense-packed using a technique called net and blow.

Two different approaches were taken for the roof.
The two second-floor bedrooms had built-in drawers on the south-facing slope that extended into the kneewall area.  The original plan was to encase them in R-7 rigid foam for air-sealing purposes.  This was deemed labor-intensive, so the entire roof line on the south-facing slope was dense-packed, bringing the entire knee-wall area inside the building envelope.
The north-facing slope was improved using the standard wall / 1st floor ceiling / kneewall / slope insulation technique.
The attic cap, above the second floor bedroom ceilings was open blown to R-50. 

Information and Tools

Minneapolis Blower Door – The blower door is the single most important tool that the auditor will use.  Even if there are no other diagnostic tools available, the blower door is essential to conduct a science-based evaluation of the leakiness of the building.

Infrared Thermal Camera – Although not completely essential, the IR camera presents a striking visual addition to the data gathered by the blower door.  Invisible problems, hidden by the structure, such as water leaks, live knob and tube wiring, missing or poorly installed insulation, and infiltration paths are revealed with the IR camera.

FYRITE PRO 125 – The Fyrite Pro 125 is a professional level combustion diagnostic tool which allows "one-hole" testing for furnace or boiler efficiency.

TI-86 CALCULATOR – The TI-86 calculator contains proprietary software that is used to calculate (among other things) the Building Tightness Limit (BTL).  This sets a lower limit on the CFM, as measured by the blower door, that the house be brought down to, and still maintain a healthy Indoor Air Quality (IAQ).

Products AND Systems

The cellulose used as the insulation is 100% recycled paper from magazines and newspaper. The ground paper is mixed with boric acid powder that acts as a fire retardant, insecticide, and rodent repellent. 

CFLs, while being 75% more efficient than an incandescent lamp giving off the same lumens, do contain trace amounts (4 mg) of mercury, so they must be disposed of as hazardous waste. 

Newer CFLs contain even less mercury, and these will be replaced soon by LED lamps which use about ¼ watt per equivalent watt incandescent bulbs. 

The existing problems with LED lamps is luminosity or the ability to sufficiently light a given square area.

Indoor Environment

Indoor environment approach

The average relative humidity (RH) in this building pre-retrofit was usually 35 – 40%.  Post-retrofit RH dropped to 10-15%. 
This caused uncomfortable levels of static electricity as well as dryness of the eyes, nose and throat.  The whole house humidifier was employed to bring the RH level to a constant 30%.  This will keep the RH high enough to eliminate static and respiratory discomfort, but low enough to prevent mold growth.

The pre-retrofit Blower Door results were 2356 CFM at 50 Pa.  Post-retrofit results were 1406 CFM at 50 Pa.  Building Tightness Limit for this home was calculated as 1251 CFM at 50 Pa.

Project Results

Lessons Learned:

The results of the project were immediate and impressive.  Energy consumption by the central air conditioner decreased by almost 40%, as evidenced by the month over month electric bill.  (The outside compressor unit was also cleaned and tuned prior to the install of insulation.) 

One issue that did arise was that the central AC unit was now “short-cycling”.  This is due to the unit being over sized for the building.  Ice tended to form on the inside expansion coils and this problem was addressed by increasing the fan speed over the coils and lowering the temperature during the first cooling cycle on the thermostat.  This allowed the unit to run longer and properly dehumidify the air.  The real solution is to downsize the tonnage from the present 3-ton to a 1-ton. 

Oil consumption declined 45% from 450 gallons in the 2005 winter before the project to 246 gallons during the 2006 winter following the project.  Further lifestyle changes resulted in a further reduction to 206 gallons used in the 2007 winter. 

Although the project was deemed a success based on the sizable reduction in fossil fuel usage, the building was near the Building Tightness Limit (BTL). 

This was the reason behind the gradual decline in RH levels.  So, the central humidifier was needed to inject moisture back into the system.  Usually, the client can be advised to discontinue the use of any humidifiers.