2017 2904 ENV Sustainable Design Principles: Week 11

2904ENV Principles of Sustainable Design

Tutorial / Workshop – Week 11

Retrofitting - Insulation

Aim: To identify a range of retrofitting options in relation to insulating your homes walls, roof and floor.

Task:

1. Paying particular attention to the ease of completing the retrofitting solution describe the advantages and disadvantages of the following and whether or not they will be a worthwhile option in relation to your home:

o Blow in foam insulation

o Blow in cellulose insulation

o Glass fibre insulation batts

o Blow in foam insulation

ADVANTAGES:

Saves energy operating costs. 30-50% per year
Reduces air and moisture infiltration-resulting in a more consistent temperature
Reduces dust and pollen infiltration
Adds structural strength to the building
Reduces the likelihood of mold
Reduces noise Reduces ice damages
Reduces HVAC capacity requirements R-values remain stable over time It has the highest performance of all insulation It is permanent and will not sag or settle

DISADVANTAGES:

The upfront cost is higher than conventional insulation
Payback period is 2-4 years It is not generally a Do-it-Yourself project
The installation process is longer The process could be messier

o Blow in cellulose insulation

ADVANTAGES:

Cellulose insulation helps reduce the mountains of discarded paper and cardboard created by a paper-hungry society.
Cellulose is treated with boric acid, which increases fire resistance, resists mold and makes it unpalatable to insects.
Some cellulose insulations are treated with an acrylic binder which ensures it settles when installed, thus reducing the long-term decrease in R-value.
Cellulose is generally cheaper than fiberglass insulation (up to 25% cheaper, in some cases).
The R-value of cellulose (roughly R-3.2 per inch) is higher than that of standard fiberglass (R-2.2 per inch).
The health risks from cellulose are far fewer than those from fiberglass.

DISADVANTAGES:

Installation costs for cellulose can be higher than for fiberglass.
Cellulose insulation creates an enormous amount of dust when it is installed, so a certified breathing mask is absolutely essential.
Dry-blown cellulose sags and settles, reducing its R-value over time.
Cellulose insulation absorbs moisture easily, which not only reduces long-term efficiency but can cause the insulation to mold and rot.
Even wet-blown cellulose can suffer from these effects. Both dry- and wet-blown cellulose need a vapor barrier.

o Glass fibre insulation batts

ADVANTAGES:

Fiberglass insulation is inexpensive and effective.
Fiberglass does not shrink.
Most manufacturers supply the material in sealed batts, covered with plastic film (perforated polyethylene or polypropylene, specifically) to avoid issues with breathing the fibers.
The plastic covering on fiberglass batts acts as an effective vapor barrier.
Fiberglass insulation does not burn.
Some fiberglass insulation uses recycled glass, reducing its ecological footprint.
Fiberglass insulation is available in medium- and high-density options (roughly R-11 and R-15 for a standard 2-by-4 wall).
Insects do not eat fiberglass insulation (or rather, it is not nutritive to them, so they have no reason to nibble).
Blown fiberglass surrounds everything inside wall cavities, providing a more consistent layer of insulation.

DISADVANTAGES:

Protective gear must be worn when installing fiberglass insulation: the tiny slivers will lodge in skin and are small enough to be inhaled.
Unless you use plastic-sealed batts, fiberglass insulation requires a vapor barrier to protect it from moisture.
Fiberglass blankets do not seal wall and ceiling spaces very tightly. Inhaled slivers of fiberglass irritate the alveoli and can cause lung disease.
There is some data which suggests fiberglass in the lungs may cause cancer, by slicing DNA and causing cell mutation, in the same way as mineral wool.
Some fiberglass insulation still uses formaldehyde as a binder, which leaks out into the air.
This product may also cause cancer.
Fiberglass settles and sags, so its R-value decreases over time.
Standard fiberglass can be crammed into smaller spaces to improve its R-value, but it needs venting if this is done (to avoid moisture buildup which will destroy its efficiency).