insulation101

8/14/2019 insulation101

1/18

Residential Insulation

Michael J. Currie

GrotonLocal.org10 October 2007


2/18

Why we insulate?

To slow the transfer of heat --

Heat is the form of energy exchanged between objects ofdifferent temperatures!


3/18

Outline

Building Envelope

R-values

Insulation Types

Insulation Case Study

Other insights Health Factors

Installation

Tax incentives

Discussion


4/18

Building Envelope -- the skin

of your structureThe building envelope consists of

all the surfaces that separate thecontrolled space from theuncontrolled space.

Primary envelope is the exteriorof your home

Secondary envelope is acontrolled space that bisects anuncontrolled space

-- ductwork in attic, pipes in

basement, refridgerator, hotwater heater

Thermal bridges are lossypathways across the envelope

To maximize efficiency of the home, all envelopes must be

properly insulated.


5/18

R-values

Industry measurement of the resistivity to heat flow,inverse of thermal conductivity (U)

R = 1/U Higher R-values (more insulation) prevent heat flow

13.8Total Wall

0.7Inside Air Film

0.51/2 Drywall

0.8Siding Wood Bevel

0.2Outside Air Film

R-valueMaterial

11.0Fiberglass Batt

0.61/2 Plywood Sheathing

R = R1 + R2 +

R3

+

Units: ft2 .F.hr/BTU


6/18

R-values contd

"Heat=1

RTHOT

#TCOLD( ) Area

Amount ofenergy youmustsupply per

hour

Area

Temp Difference

R-value

Energy UsageFactor

This is the basis for your insulation strategy!


7/18

Example - Your front door

"Heat=1

RTHOT

#TCOLD( ) Area

1

3.7

65" 25( )

170 =

BTU/hr

21

(3 x 7)

Annual heat loss is equivalent to 5 gallons of fuel oil.(1 gallon fuel oil = 140,000 BTU)


8/18

Recommended R-values

38

38 38

49

25

11 to 22

10 1119

Band Joist

30


9/18

Types of InsulationR per inch

Source: DOE Insulation Factsheet

3.1

2.1

various

4-6.5

2.2 - 3.7


10/18

R-value caveats

Source: Oak Ridge National Labs

Insulation manufacturers measure R-values in a lab, not in the realworld

Center of Cavity -- only insulation, no structure,WYSIWYG

Clear Wall -- wall w/ minimal studs

Whole Wall -- wall w/ windows, corners, etc.

For a 2x6 wall w/ R-19 batts and studs 24 o.c.

13.716.421.6

Whole WallClear WallCenter of Cavity

2/3

Extreme Cold Air and Moisture degrade R-value performance of batt and loosefill insulation

Moisture -7.5% per 1% moistureExtreme Cold


11/18

Heating and cooling days

Degree day captures

the average

temperature below

the typical heatingset-point of 65 F

Example: 10 F

average temperature

gives 55 degree days

Heating Days

6000 degree days

Cooling Days

500 degree days

In New England, heating dominates energy consumption

-200

0

200

400

600

800

1000

1200

1400

Jan Mar May Jun Aug Oct Nov

2005

2006


12/18

Residential Case Study

Built: 1978 Living Space:2400 sq ft. Perimeter: 156 ft.

Energy Usage:

800 gallons fuel oil and 20kWh per day-(100 millionBTU during the heatingseason)

Construction:

2x4, R-11 batts

R-19 in cathedral ceiling

Single/Double Pane Windows

No basement insulation

What are the available options?


13/18

Upgrading Windows

360004.0Triple Pane

$5.63 per

window480003.0

Double Pane,

low e

$16.88 per

window720002.0

Single Pane w/

storm

-1440001.0Single Pane

Case study

savingsBTU/year/ sq ft.R-valueType

Assumes: Fuel Oil is $2.50

Payback time is 50 to 200+ years! - Very bad news


14/18

Insulating Basement

8 below ground level temperature is 50 - 55

F during the winter.The equivalent number of degrees days during the heating season is 1800.

For 1300 square feet of floor (R-value = 1.6), the heating load isequivalent to 300 gallons of fuel oil ($750). The actual value is higher ifthe basement has drafts, i.e. the underground temperature is higher.

How to insulate?

Do not use fiberglass if thearea is moist. Yourinvestment will be ruined.

Ceiling -- basement isunheated, attacks the problemat the source.

Walls -- basement is heated,fairly dry.

Always insulate band joist R-30


15/18

External Foam under clapboarding Can you economically add foam over siding, if you intend to

change siding?

5-1 Rigid Insulation

0.8-Siding Wood Bevel

1.0-Air Pocket

20.6

0.7

0.5

11.0

0.6

0.8

0.2

New R-

value

13.8Total Wall

0.7Inside Air Film

0.51/2 Drywall

0.8Siding Wood Bevel

0.2Outside Air Film

Old R-

value

Material

11.0Fiberglass Batt

0.61/2 Plywood Sheathing

Case Study: 1500 sq. ft. of siding -- savings of 53 gallons offuel oil or $115 per year.

Not economical ifyou need to change any aspect of window

detail, most likely over 10 year pay back time!


16/18

Case Study Conclusions

Basement Insulation would be a sure bet. Large possiblesavings, with easy access on the inside.

Replacement windows and insulation under newclapboarding are not cost effective.

Other options:

For windows: R-5 insert into windows at night would yield $5 perwindow per year.

Two other elements of the heat loss equation

Reduce square footage -- only heat required rooms

Reduce setpoint -- 7 degree setback for overnight saves 11% acrosswhole structure during the heating season

Can be achieved with programmable thermostats


17/18

Health Factors Vermiculite fill may contain asbestos

70% of vermiculite mined from contaminated mine in Libby, MT

Fiberglass insulation is a skin and airway irritant, and can containcarcinogens, formaldehyde allergens

Wet insulation supports mold growth Installation

Improper installation may degrade whole wall r-value

Fiberglass should not be compressed, voids behind junction boxesshould be insulated, area around door/window frames

Vapor barrier products must have vapor barrier facing high

moisture area.

Tax Incentives Energy Policy Act of 2005 -- credit of 10% up to $500 for the cost

of qualifying energy efficiency purchases, i.e. insulation andappliances

Other Factors


18/18

Discussion

insulation101

Documents

Transcript of insulation101