RESIDENCE CASE STUDY #1
Background
Newly Built Town Homes - Salisbury, MA Energy Egghead conducted a series of energy audits that were performed on several townhouses at a new residential development. Though there were different results for each of the audits, this case study is representative of how many homeowners were able to start saving money on energy costs and create a more comfortable living space.
Audit Focus and Recommendations
As with all audits at this development, this representative audit consisted of a house depressurization test, an infrared scan using a high-resolution camera, and a duct leakage test on a 1,780 square foot town house built in 2008. The occupants complained of drafty conditions and feeling cold soon after the heating system cycled off during winter months. They also complained that the units were not staying cool and dry for very long, after the air conditioning system cycled off during the summer months.
The house depressurization test (using a blower door) showed that the natural ventilation rate was (90 cubic feet per minute-CFM) above the American Society of Heating Refrigeration and Air Conditioning Engineers (ASHRAE) Minimum Ventilation Rate (MVR) set forth in ASHRAE 62.2. Given the number of bedrooms and according to the ASHRAE 62.2 formula, the MVR for this home is 40 CFM.
A considerable amount (40%) of the duct system used to supply heat and conditioned air to the house was located in the unconditioned basement and attic. The duct leakage test showed an excessively leaky air duct system, which was about double the code-plus standard of 8% of the total square footage for the home. Due to this distribution loss, the overall efficiency of the heating and air conditioning system was significantly reduced.
Infrared inspection taken from the interior during the house depressurization test showed significant air leakage in walls and ceilings. The attic had about 24 inches of loose-fill fiberglass that was hydraulically applied on top of the floor. The basement had a considerable area of 2 x 4 framed walls on top of the foundation, with un-faced fiberglass batts poorly fitted in the wall cavities.
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Infrared Image of Second-Floor Ceiling Taken During House Depressurization Test |
Prior to insulating the roof deck, an infrared image of the second floor ceiling shows significant differences in surface temperature (purple is cooler, yellow is warmer) due to loose-fill fiberglass insulation that is not in full contact with the attic dry wall floor. The result is substantial heat transfer through the second floor ceiling into the attic.
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Infrared Image of Basement Wall Taken During House Depressurization Test |
Fiberglass batts in framed section of basement wall show gaps and cold air infiltration (in purple) where framing sits on the concrete foundation. Image taken prior to sealing and insulating with closed-cell foam.
Recommendations:The recommendation after the audit was to foam seal the attic roof deck and gable ends down to and including the tops of the wall plates. Sealing the tops of the wall plates will help to slow convective heat loss from air moving through fiberglass batts in wall cavities.
A recommendation was also made to apply closed-cell spray foam to the rim-joist and wood-framed wall cavities in the basement that previously had only open-faced fiberglass batts. This would not only reduce air infiltration, but bring the basement heating and cooling units and air ducts into more conditioned, temperature-moderated space.
Resulting Conservation Services
Air infiltration tests using the blower door before and after insulation showed a 26 percent drop in air exchange rate.
With the utility rebate and tax credit, the economics were quite favorable to the homeowner. The cost of foaming the attic and basement was $3,590. The utility company rebate was $2,000 and the tax credit was $1,077. Thus, the net cost to the homeowner was $513. Savings is projected to be about $200 per year providing about a 2 and ½ half year payback. Homeowners experienced a noticeable increase in their ability to maintain comfort during the heating and cooling seasons.
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Closed-cell foam insulation is shown on the attic roof with a section of air duct at the bottom of the picture on the attic floor, which is now inside the conditioned space. |
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Closed cell foam is shown where fiberglass is pulled back and along rim joist at top of wall in basement. |
RESIDENCE CASE STUDY #2
Background
An attic in an old house had about 3 inches of previously installed vermiculite insulation between a plaster and lathe ceiling below and wide pine attic floor boards. This was quickly determined to be inadequate and it was pointed out that a significant amount more insulation was needed.
Audit Focus and Resulting Conservation Services
Given that the vermiculite contained asbestos, it was decided to leave it alone and cover it with cellulose. Any air sealing in the attic was prohibited due to the fact that the vermiculite would have to be disturbed. In order to achieve a high R-value, it was necessary to add more depth to the floor. The wide pine floor boards were removed temporarily while 2" x 10" joists were sistered to old 4" x 4" joists spanning the width of the floor and providing additional support to what was a bouncy floor.
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A new 2" x 10" floor joist is barely visible with cellulose insulation filling bays to its left and right. |
The homeowner rented a cellulose blowing machine and installed insulation to a depth of 14 inches, creating an R-value of 49. The floor boards were re-used and placed on top of the newly framed floor. Adequate head room was maintained in the attic, which continued to be used for storage.
RESIDENCE CASE STUDY #3
Background
An energy audit was conducted by Energy Egghead and areas of significant energy loss and potential savings were identified. Improvement options were prioritized according to cost-effectiveness and anticipated increase in comfort. Four energy improvements were implemented. The energy conservation measures taken are typical improvements of which many homeowners can take advantage and start saving.
Audit Focus and Result
Crawl Space A thermal infrared scan showed a significantly colder section of kitchen floor over an un-insulated crawl space compared to floor temperature that was above the basement. In order to increase comfort in the kitchen at the start of winter, the homeowner chose to have the crawl space sealed and insulated first. A continuous layer of moisture-proof closed cell foam was applied to the ceiling, rim joist, and foundation. Additional insulation was added and a vapor barrier was installed.
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Image shows drop in floor temperature over crawl space. Note that the objects in the kitchen over the crawlspace are at the same temperature as the floor in the foreground (yellow). The cold temperature (red) is confined to the floor over the crawl space. |
Heating and Cooling Air Ducts
The home, built in the 1970s, had air ducts that were found to be unsealed and un-insulated at the time of the audit. Energy loss from this type of distribution system is significant particularly when most of the air ducts are located in an unconditioned basement. All seams and holes were sealed with duct sealant prior to adding 3-inch thick aluminum-faced duct insulation on all ducts from the registers to the air handler (or blower).
Attic The attic was determined to be an area where substantial savings could be made once properly sealed and insulated. Six-inch thick fiberglass batts were in place at the time of the audit. Recessed light fixtures with holes in the cans among many other points that allowed air to leak from the second floor living area into the attic were identified.
Energy Egghead foam sealed the attic floor, installed air-tight insulated boxes over the recessed light fixtures, and added a deep layer of loose-fill insulation providing an R-40 to R-50 insulation value.
Basement The rim joist, which is typically 2x8-inch or 2x10-inch wood framing that sits on the concrete foundation of a house, was found to be allowing in a significant amount of outside air during the blower door test. This condition is often detectable during cold weather by putting one's hand near the rim joist. Warmed air is forcing its way out at the top of the house and must be replaced, which occurs at the lowest pressure point—the rim joist.
The rim joist around the entire basement was sealed and insulated with an application of closed-cell foam that covered an area from the ceiling to the top of the foundation.
RESIDENCE CASE STUDY #4
Background
A 1970s home was purchased that had a new energy star furnace installed just prior to sale. However, the home had seemingly high heating costs.
Audit Focus and Resulting Conservation Services
A duct leakage test showed the home had un-sealed and un-insulated ducts. There was excessive leakage at the seams, through holes in the ducts, at the air handler, and at the registers under the floor. All of these points were leaking heated air "to the outside," that is outside the area to which heating is intended. The solution was proper sealing and insulating of leaky air ducts, as shown below.
Energy Egghead first sealed the plenum and ducts from the air handler to the registers. Foil-faced duct insulation was installed providing an R-5.7 over the entire system. The homeowner now had highly-efficient heat distribution system to match the energy star rated furnace.
RESIDENCE CASE STUDY #5
Background
This is a 4,000-square-foot new house with two gas-fired heaters, each dedicated to one floor, using forced hot air.
This home is extremely hard to keep warm. Concern surrounds building envelope and sealing.
"Bonus room" above garage is particularly hard to heat and is often cold.
Audit Focus and Result
Energy Egghead conducted an air infiltration test, examining the air duct system for leaks during test.
We also examined potential air infiltration leakage throughout house
The air infiltration rate is normal for newly constructed house.
Windows are tight with no major sources of air infiltrating. The air duct system shows some leakage in attic ducts.
Room above garage has no major leaks.
Homeowner now knows house is actually "air-tight" with no action necessary. However, some duct sealing needs to be done, and homeowner learned that "bonus room" above garage requires additional sealing and insulation above and beyond that used for the main house envelope, which was not considered during design and construction.
We recommend that homeowner have us conduct infrared scan on room above garage with blower door running to make sure no insulation is missing and identify areas of heat loss.
RESIDENCE CASE STUDY #6
Background
A home built in Newton in the 1930s was a new purchase. Plans for a major addition on the north side of the house and a new central heating / cooling system were part of major renovation. An energy audit was requested to determine if the existing air infiltration rate and insulation were satisfactory. Determining heating and cooling loads were also an important part of the audit.
Audit Focus and Result
Energy Egghead conducted a comprehensive audit that modeling thermal performance of existing conditions as well as projected conditions from the new addition. As a result, the new homeowners learned that the existing house was adequately air-tight and required no additional insulation. They were also able to install appropriately-sized heating and air conditioning units saving on what might have been systems that were too large or too small carrying unnecessary costs.
RESIDENCE CASE STUDY #7
Background
This home has an insulated second-floor ceiling, but no insulation in walls. House has high heating bills and is uncomfortable when windy.
Audit Focus and Result
The Energy Egghead audit found that the north facing wall has poorly installed fiberglass insulation behind interior wall that is made of 6-inch wide pine boards. Air infiltration test with blower door revealed significant volume of air pouring in between every board from floor to ceiling.
Audit confirms that the walls need insulation and a cost/savings analysis was done showing short pay-back on blown-in insulation. Old knob and tube electrical wiring is still active in areas and must be removed prior to insulating.
Combination of sealing air-infiltration in north wall and other identified points plus insulating walls will wield significant savings to homeowner.
RESIDENCE CASE STUDY #8
Background
This is a large, newly constructed home (2004), which is approximately 7,000 square feet with 12-foot ceilings. The north-side dining room and master bedroom are extremely cold, even when the rest of the home is warm.
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Audit Focus and Result
Energy Egghead conducted an air infiltration test and an infrared scan. We found that outside air is literally pouring in where second floor deck meets the house, causing the first floor ceiling and the master bedroom floor to be at very low temperatures. Connected interior walls also show severe cold dropping into walls inside house.
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Family room bar area showing cold air infiltration into the ceiling, apparently originating at the deck/wall interface on the exterior of the north (back wall). The wall on the left appears to be insulated, but the cold air is dropping into the wall cavity where insulation batts have gaps. |
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Family room front area facing south (front wall), cold air infiltration continues in soffit. |
We recommend sealing at deck / exterior wall interface and insulating first-floor ceiling under master bedroom. A follow-up infrared scan will insure that remedial sealing and insulation is complete.
RESIDENCE CASE STUDY #9
Background
Homeowner complained of a severe moisture problem in the attic and a drafty uncomfortable family room. New insulation had been added in the attic in the previous fall season.
Audit Focus and Result
The focus of the audit was to identify the source of the moisture problem in the attic and to find the origin of the cool/drafty condition in the family room. Additional findings and recommendations are included.
An excessive amount of moisture was evident on most surfaces in the attic. The moisture was in mostly in the form of frozen or crystallized water covering the sheathing between roof joists.
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Unfrozen, but very wet sheathing was evident in three locations near the soffit where bathroom vents and the clothes dryer vent ducts were evidently attached to the soffit. These vents appear to be bringing a significant level of moisture into the soffit. The moist air is moving laterally and up the bay vents into the attic (see photo). This is the apparent source of the attic moisture problem. The vents need to be connected to ducts/piping that vent to the outdoors. This should solve the moisture problem in the attic. Insulation levels in the attic were more than adequate and found to be dry where evaluated. |
The blower door test showed that the house was in a normal range for air-tightness. However, the blower door test revealed significant air leakage from recessed lights in the family room. Air-tight recessed light fixtures known as Insulated Contact (IC) - rated fixtures to replace the existing lights was recommended. A gap around the front of the fireplace was found to be leaking cold air. Sealing with an appropriate material for use on fireplaces was recommended. Adding blinds and/or drapes on windows to help increase the comfort level in the family room was also suggested.
COMMERCIAL OFFICE BUILDING CASE STUDY #1
Background
A three-floor commercial building with approximately 10,800 square feet of office space had seemingly high heating and air-conditioning costs according to the building manager. |
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Audit Focus and Result
The focus of the audit was requested to identify and prioritize energy conservation measures. The primary heating and cooling system for the second and third floors (about 2/3rd of total space) is located in the unconditioned attic. Excessive leakage from the air duct system into the attic was identified. Sealing and adding insulation to the air duct system was recommended as a first priority. Cellulose insulation in the attic had been blown in place years prior and had settled to about 4 inches depth. Adding another 4 inches of cellulose was also recommended as a second priority. Overall building leakage measured in a satisfactory range compared to buildings of comparable size and age. However, the blower door test revealed where inexpensive weatherizing and sealing would contribute to reduced outside air infiltration and create more comfortable conditions for tenants. Lastly, replacing old thermostats with new digital programmable thermostats was recommended.
