Marshfield Energy and Climate Change Committee

Notes of Weatherization Workshop

November 17, 2007

RIP

High Points

1)      Audits available from Central Vermont Community Action for $250 with no income sensitivity requirement.

2)      Fiberglass insulation ineffective if air leaks are not separately prevented

3)      Dense pack cellulose or spray foam are preferred insulation types because form air barrier and insulation. Dense pack cellulose best to retrofit existing homes. Spray foam most expensive.

4)      Unsealed house acts like a chimney with warm air escaping upward and cold air entering along the bottom

5)      Drafty houses have low humidity because replacement air drawn in along the bottom is low humidity

6)      Leaks of heated air with higher moisture cause condensation on the outer sheathing which is cold--- gives rise to paint lifting and wood rot.

7)      Balloon frame houses like post and beam are difficult to air seal and properly insulate

8)      Air sealing is even more important than insulation—should be the first order of business.

9)      Blower door air tightness test very effective in identifying air leaks. Infrared camera allows honing in on the air leak and poor insulation areas. Do not hire a contractor to find and fix air leaks/insulation problems that does not use a blower door.

10)  Efficiency Vermont has incentives for electric water heater; space heater and central heat change outs and can reduce the interest on loans for energy improvements by 3.5%.

 Ken Jones-Montpelier Energy Coordinator

Montpelier is forming an energy coop to provide services to residents. They have some funding that will allow a reduction to $150 from $250 for an energy audit by CVCAC and a buy down of interest by an additional percent on loans for energy improvements already qualified for a buy down of 3.5% by Efficiency Vermont.

Walter Scott-Efficiency Vermont

1)      Old homes not improved—no airflow control, cold drafts, low humidity (many leaks).

2)      New buildings (or skilled retrofits) can be quite tight---need to consider indoor pollutants, condensation if not properly ventilated, indoor pressure (check with blower door) combustion safety (need direct line to outside)

3)      Heat transferred by conduction --- heat moves through solid; quantity of heat proportional to change in temperature from one side of solid to the other

4)      Heat transferred by convection---heat carried by moving liquid (air); heat moves from high to low pressure; air leaving building takes heat with it and the same amount of heat must be added to incoming air to maintain temperature.

5)      Heat by radiation---heat flow through empty space like light; you feel hot and cold surfaces; radiance affects our feeling of warmth; amount of heat transferred is proportional to the temperature difference from ambient air and the radiant surface.

6)       BTU is measure of heat--- heat required to raise one pound of water one degree Fahrenheit. Generally, old houses might need 100 to 150,000 BTU/hr and new houses about 60 to 80,000 BTU/hr during cold winter days.

7)      R-value is a measure of a material’s resistance to heat moving through it; insulation with higher values allow less heat transfer; can add R values for multiple layers of insulation, but can’t average them.

8)      Thermal envelope of building; air barrier and insulation must be in contact; separation could allow convection currents to reach the insulation and reduce its effectiveness

9)      Insulation; traps air to reduce transfer; if air is flowing through insulation greatly reduces R-value; dense pack cellulose (3.5 pounds/cubic foot) will form effective air barrier getting into all the nooks and crannies and good insulation; all air flow must be sealed and insulation must fill all openings or the remaining uninsulated areas will allow larges amounts of heat lose.

10)  Insulation types; the fibers---fiberglass, rock wool, cellulose, newspapers, sawdust; the foams----extruded and expanded polystyrene, urethane, isocyanurate and low density open cell

11)  Fiberglass insulation; not a good insulator unless fitted very well with no chance of air flow through the insulation, air flow will significantly decease the nominal R value of 3 to 3.5per inch

12)  Cellulose Insulation; recycled newspaper with fire retardant and treated to reduce animal damage; lose pack less effective than dense pack; dense pack (3.5 pounds per cubic foot) in a closed cavity greatly reduces air flow, is fire proof, and has a R value of 3.6 to 3.8/inch; new walls use netting, dense pack then sheetrock; better than vermiculite at preventing animal damage.

13)  Expanded Polystyrene, Extruded Polystyrene (blue board) and foil faced Urethane all are in 1 or 2 inch thick boards with an Rvalue of about 4 to 6/inch.

14)  Liquid spray forms of foam (high density closed and low density open cell) have excellent air sealing and fit properties;  Rvalue 3.5/inch for open and 6.5/inch for closed; most expensive insulation type.

15)  Use low expanding foam around windows and doors for air sealing so won’t bend the frame when it expands

16)  Air sealing is extremely important; not only does it stop the escape of heated air which heat must be replaced but the heated air will take moisture which will condense when it reaches the cooler outside sheathing causing paint to lift and wood to rot

17)  Many older houses have a balloon frame where the vertical members of the outer walls were longer than used in modern construction and extended from the sill on the foundation all the way to the eves. Essentially there was an open cavity four to six inches wide along the entire side and end of the house from the sill to the eves. This method of construction was generally abandoned for the current day platform frame method of building a multistory home one level at a time with definite closure of the outside wall to the floor at each floor level. It is much more difficult to retrofit a tight air seal in a balloon frame home like many post and beam homes of the 1800s.

18)  Air Flow in home; air moves from warm to cold; unsealed homes act like a chimney because warm air flows out the top and cold air flows in along the bottom with the flow increasing during windy weather because of the air pressure differential caused on the downwind side of the house; replacement air is very dry so a drafty house has low humidity; in a tight house need to have appropriate controlled ventilation to bring in air to replace that used by the combustion devise and to prevent build up of harmful pollutants but it’s more efficient to entirely seal the home and then install a small ventilation fan to ventilate a regulated amount. Sheetrock is a great air barrier and Tyvek lets moisture through but stops air unless under pressure.

19)  Common leak locations are door and window casings, openings between foundation and sill, between wall and roof or ceiling, between floors particularly in balloon frame houses, utility penetrations, around tub and shower, tops of interior and exterior walls, penetrations in top plates; stuffing fiberglass does not seal, use foam; do air sealing before insulation.

20)  Bath fans need to be vented outside and be on a timer, CO alarms are set to go off at 70 parts per million CO which is a very dangerous level from a safety standpoint --- if it goes off act quickly to get out; have combustion test regularly on you furnace/boiler to make sure the chimney and combustion unit are exhausting the CO up the chimney without any release elsewhere.

21)  Blower Door Test----depressurize home by pulling enough air out with a blower so that the pressure inside is 50 somethings? below the outside air pressure. This is equivalent to the pressure differential across a house caused by a wind of 20 miles per hour. This test can be used to identify the air leaks where outside air is leaking into the home, recheck the tightness again after fixing the leaks and can verify when the home has reached its Building Tightness Limit. Do not use a contractor to audit your home that does not have access to a blower door.

22)  Infrared Camera---- this technology, if used in the winter, shows up warm areas as white or light colored and cool areas as dark generally signifying air leaks or inadequate insulation. Cameras are usually used in conjunction with the blower door to further refine the location of the leaks.

23)  Suggested that homeowners use contractors certified by the Building Performance Institute. There are 30 contractors certified statewide listed on the EV website.

24)  Efficiency Vermont has some incentives for improvements to reduce electrical energy use. Up to $500 for electric water heater conversion, up to $500 for space heater conversion, up to $1000 for central heat conversion. These incentives only apply if current kwhr use reaches a certain level. EV also can buy down 3.5% of interest on loans for thermal efficiency improvements. They have four lending institutions participating in that program where the institution charges say 8% but the borrower pays only 4.5% with EV picking up the rest of the interest.