Types Of Insulation
First, to understand the types of insulation and how they are related and compared, you first need to understand R Value….
R-value is the unit used to measure an insulating material’s capacity to resist heat flow. Materials with higher R-values are better insulators.
“R-Value” (an expression of heat transfer resistance) is the standard for measuring insulation performance. At R3.6 to 3.8 per inch, cellulose insulation is considerably better than most mineral fiber blowing wools. But, R-Value is only ONE factor in the energy efficiency of a home. Studies of actual buildings regularly show that cellulose-insulated buildings may use 20% to 40% less energy than buildings with fiberglass, even if the R-value of the insulation in the walls and ceilings is identical.
Blower Door for Depressurization Testing
A blower door is a powerful fan that mounts into the frame of an exterior door. The fan pulls air out of the house, lowering the air pressure inside. The higher outside air pressure then flows in through all unsealed cracks and openings. The auditors may use a smoke pencil to detect air leaks. These tests determine the air infiltration rate of a building.
Blower doors consist of a frame and flexible panel that fit in a doorway, a variable-speed fan, a pressure gauge to measure the pressure differences inside and outside the home, and an airflow manometer and hoses for measuring airflow.
There are two types of blower doors: calibrated and uncalibrated. It is important that auditors use a calibrated door. This type of blower door has several gauges that measure the amount of air pulled out of the house by the fan. Uncalibrated blower doors can only locate leaks in homes. They provide no method for determining the overall tightness of a building. The calibrated blower door’s data allow the auditor to quantify the amount of air leakage and the effectiveness of any air-sealing job.
Hot To Prepare Your Home For Such A Test
Take the following steps to prepare your home for a blower door test:
- If you heat with wood, be sure all fires are completely out – not even coals – before the auditor arrives. Remove any ashes from open fireplaces.
- Plan to do a walk-through of your home with the auditor. Be prepared to point out areas that you know are drafty or difficult to condition comfortably.
- Expect the auditor to request access to all areas of your home including closets, built-in cabinets, attics, crawl spaces, and any unused rooms.
- The auditor will need to close all exterior doors and windows, open all interior doors, and close any fireplace dampers, doors, and woodstove air inlets.
- Expect the auditor to set controls on all atmospheric fossil fuel appliances to ensure that they do not fire during the test. The auditor should return them to the original position after the test.
- Expect the test to take up to an hour or more, depending on the complexity of your home.
Understanding Energy Bills
Understanding Basic Energy Principles
Basic Energy Principles
Laws of Thermodynamics
Understanding Stack Effect
“Stack Effect” is when warm air moves upward in a building. This happens in summer and winter, but is most pronounced in the winter because indoor-outdoor temperature differences are the greatest. Warm air rises because it’s lighter than cold air. So when indoor air is warmer than the outdoor air, it escapes out of the upper levels of the building, through open windows, ventilation openings, or penetrations and cracks in the building envelope. The rising warm air reduces the pressure in the base of the building, forcing cold air to infiltrate through open doors, windows, or other openings. The stack effect basically causes air infiltration on the lower portion of a building and exfiltration on the upper part.
Mechanical equipment such as fans and blowers causes the movement of air within buildings and through enclosures, which can generate pressure differences. If more air is exhausted from a building than is supplied, a net negative pressure is generated, which can induce unwanted airflow through the building envelope.
Bathroom exhaust fans, clothes dryers, built-in vacuum cleaners, dust collection systems, and range hoods all exhaust air from a building. This creates a negative pressure inside the building. If the enclosure is airtight or the exhaust flow rate high, large negative pressures can be generated.
Air Leakage Basics
Air leakage control is an important but commonly misunderstood component of the energy efficient house. Tightening the structure with caulking and sealants has several positive impacts.
A tight house will:
- Have lower heating bills due to less heat loss
- Have fewer drafts and be more comfortable
- Reduce the chance of mold and rot because moisture is less likely to enter and become trapped in cavities
Have a better performing ventilation system
Potentially require smaller heating and cooling equipment capacities.
Air leakage (sometimes called infiltration) is the unintentional or accidental introduction of outside air into a building, typically through cracks in the building envelope and through use of doors for passage. In the summer, infiltration can bring humid outdoor air into the building. Whenever there is infiltration, there is corresponding exfiltration elsewhere in the building. In the winter, this can result in warm, moist indoor air moving into cold envelope cavities. In either case, condensation can occur in the structure, resulting in mold or rot.
Homeowner Checklist to Save Energy
Take this with you!
We have put this into PDF form so you can have this checklist with you wherever you go.
It also includes two bonus tips from our Expert Tim!
Understanding of Principles of Heating and Cooling
Principles of Heat Transfer
Sun and Heat Movement
Fire Protection With Insulation
Insulation plays an important role in how a fire spreads and moves around the home. We don’t like to think about the scenarios but unfortunately they do occur and need to be addressed before the possibility happens.
Tests conducted by Underwriters Laboratories Inc.® show that Cellulose insulation provides an effective 1 hour fire rating. This will slow the spread of a fire allowing you more time to escape any danger. This is because Cellulose is specially treated using Borate Compound Chemicals as a fire retardant in the manufacturing process to meet or exceed all fire safety requirements.
The following table shows two key measures of how three types of insulation react in a fire: speed of “Flame Spread” and “Smoke Developed.” The lower the numbers, the better.
Flame Spread refers to the speed at which flames “spread” along the surface of the insulating material. “Smoke Developed” refers to the amount of smoke that is produced while the product burns. In most house fires, it is not the flames which cause serious personal injury but rather smoke inhalation. Smoke also increases confusion during a crisis and obscures important fire exits.
Pest Control With Insulation
Another important feature when opting for cellulose insulation represents the fact that it is treated with boric acid, which is an efficient pest hindrance. When insects absorb or come into contact with boric, it kills the creatures without breach into your home. The result is a thermally and acoustically superior insulation product that is environmentally sensitive and also helps control pests!
Sound Control With Insulation
Insulation provides very effective sound control to minimize outside noises and between rooms (if the interior walls are insulated). Many people only focus on the energy savings that can be achieved with Cellulose insulation but overlook the benefits that come from improved sound insulation. If you have ever walked into a house that is not insulated you will immediately notice that noises from outside of the house are “louder” than in an insulated home. This is because the sound transmission coefficient (STC) is lower. The STC is a calculation of the acoustic performance of a wall or ceiling and a higher number is better than a lower number.
Drywall and lumber have low STC ratings compared to walls or ceilings with Cellulose insulation in them. Unless you are looking for perfect acoustic control, adding Cellulose insulation within interior walls is the most cost-effective and efficient way to minimize sound transmission between rooms or from the outside.
How Moisture Moves
Bathrooms Grow Mold and Mildew
Your bathroom is likely one of the most humid rooms in your house. Every time you take a hot shower or use warm water to wash your hands, you’re releasing more moisture into the air. Moist air provides a perfect environment for mold and mildew growth. There can be serious effects to this, too — both microscopic organisms can be detrimental to your health.
Unfortunately, there’s no real way to keep mold spores out of your house. The only way to prevent mold and mildew from thriving in your home is to regulate the interior humidity. Mold lies in hibernation everywhere and grows when the moisture in the air is suitable to its needs. So the problem really lies with home ventilation, condition, materials and insulation. All of which can be controlled.
In addition to being dangerous for your health, mold and mildew can damage walls, floors and anywhere else they grow. This compromises the structural integrity of your home posing even greater risk to all who live in it.
What is an ice dam?
An ice dam is a ridge of ice that forms at the edge of a roof and prevents melting snow (water) from draining off the roof. The water that backs up behind the dam can leak into a home and cause damage to walls, ceilings, insulation, and other areas. Figure 1 shows a cross section of a home with an ice dam.
What causes different roof surface temperatures?
Since most ice dams form at the edge of the roof, there is obviously a heat source warming the roof elsewhere. This heat is primarily coming from the house. In rare instances solar heat gain may cause these temperature differences.
Heat from the house travels to the roof surface in three ways: conduction, convection, and radiation. Conduction is heat energy traveling through a solid. A good example of this is the heating of a cast iron frying pan. The heat moves from the bottom of the pan to the handle by conduction.
If you put your hand above the frying pan, heat will reach it by the other two methods. The air right above the frying pan is heated and rises. The rising air carries heat/energy to your hand. This is heat transfer by convection. In addition, heat is transferred from the hot pan to your hand by electromagnetic waves and this is called radiation.
Another example of radiation is to stand outside on a bright sunny day and feel the heat from the sun. This heat is transferred from the sun to you by radiation.
In a house, heat moves through the ceiling and insulation by conduction through the slanted portion of the ceiling (Figure 1). In many homes, there is little space in regions like this for insulation, so it is important to use insulations with high R-value per inch to reduce heat loss by conduction.
The top surface of the insulation is warmer than the other surroundings in the attic. Therefore, the air just above the insulation is heated and rises, carrying heat by convection to the roof. The higher temperatures in the insulation’s top surface compared to the roof sheathing transfers heat outward by radiation. These two modes of heat transfer can be reduced by adding insulation. This will make the top surface temperature of the insulation closer to surrounding attic temperatures directly affecting convection and radiation from this surface.
There is another type of convection that transfers heat to the attic space and warms the roof. In Figure 1, the winding arrow beginning inside the house and going through the penetration in the ceiling, from the light to the attic space, illustrates heat loss by air leakage. In many homes this is the major mode of heat transfer that leads to the formation of ice dams.
Exhaust systems like those in the kitchen or bathroom that terminate just above the roof may also contribute to snow melting. These exhaust systems may have to be moved or extended in areas of high snow fall.
Other sources of heat in the attic space include chimneys. Frequent use of wood stoves and fireplaces allow heat to be transferred from the chimney into the attic space. Inadequately insulated or leaky duct work in the attic space will also be a source of heat. The same can be said about kneewall spaces.
So it is primarily heat flowing from the house that is causing the nonuniform temperatures of the roof surface leading to ice dams.
Ice dams can be prevented by controlling the heat loss from the home.