To truly maximize savings on electricity bills, a contractor must take the blinders off. Instead of focusing on just the heating and cooling equipment, you must consider the entire home. In particular, focus on correctly installed ductwork, adequate insulation and avoiding the bad types of infiltration.
According to the EPA, 20-30% of the air moving through ductwork is lost due to leaks, holes and poorly connected ducts. In other words, around 25 cents are wasted for each dollar spent on the operation of heating and cooling equipment. Duct leaks can also degrade indoor air quality by drawing in pollutants from the attic and crawlspaces, which may include allergens such as insulation, dirt, dust, animal urine etc. Poor ductwork performance can also result in hot/cold spots throughout the home. Not only are these uncomfortable, but they also can cause respiratory ailments.
In addition, a system with airflow restrictions will likely experience more breakdowns and costly repairs over its shortened life expectancy due to additional stress on the equipment. It is also more prone to “freezing up” which can cause water damage to the equipment and home in many cases.
Finally, remember that Efficiency Ratings and Capacity Calculations are based on ideal laboratory conditions. When airflow is restricted by poorly-installed ducts, both of these functions can drop dramatically, robbing homeowners of expected utility bill savings from recently purchased “high” efficiency equipment.
Home Envelope: Insulation
Insulation acts as a thermal barrier that helps slow the movement of heat. Poor insulation levels allow heat to transfer in and out of the structure at a high rate. Since it is the heating/cooling system’s job to transfer heat (either into the home for heating or out of the home for cooling), the HVAC system and home insulation work hand in hand.
When there are low levels of insulation, the HVAC system has to perform more work to keep the house comfortable, which results in higher utility bills. You can deliver a better project if you address building envelope issues prior to installing or upgrading equipment.
In addition, uneven levels of attic insulation can contribute to hot and cold spots in the home. If room a has adequate levels and room b has very little, room b will likely be uncomfortable because heat is entering or leaving that area at a higher rate when compared to room b.
We have seen many cases in which homeowners will adjust the thermostat to properly condition room b, which over conditions room a. This is a waste of electricity, and makes the system work harder to overcome an issue with the home construction. In such a situation, your clients are paying for the problem whether they get it fixed or not.
Often overlooked areas are knee walls (interior walls that stick up in the attic that are adjacent to the area you are attempting to condition). Builders will often roll batting in between the framing for these areas and if not secured properly, these will fall down causing a “heat hole” where there is hardly any resistance to heat transfer.
Even when the insulation is there, issues can arise from Thermal Bridging where a large percentage of the overall r-value of the wall is lost to exposed framing. To prevent this, install insulation board backing against the framing. This will also help secure the rolled batting insulation, which improves comfort and saves on utility cost.
Home Envelope: Infiltration
Infiltration, also known as air leakage, occurs via open areas in the building construction from the living space to outside. There are two types of infiltration: Bad infiltration and good infiltration.
Bad Infiltration occurs due to open areas in the attic and/or crawlspace that allow air to pass into the home. This brings humidity and contaminants into the home (insulation, dust/dirt, animal excrement/urine, etc) and contributes to faster heat transfer. Bad infiltration contributes to higher electric bills, poor air quality, and discomfort throughout the home
Here are some examples of sources of bad infiltration:
- Leaky Can Lights: In this case, use higher quality can-lights which seal much better. Kits can be installed to make existing ones tighter. You can help customers further save on electrical usage by upgrading them to tight LED lighting fixtures.
- Penetrations in wall top plates: These are electrical and plumbing holes drilled in the wall to run piping/wiring into a wall cavity.
- Attic Accesses: For example, pull down stair cases and scuttle holes
- Unsealed wall chases for ductwork
- Unsealed ductwork
There is also good infiltration, such as mechanical ventilation, doors and windows. Good infiltration brings fresh outdoor air that helps dilute and replace stale/polluted indoor air. This is important to balance a healthy home and minimize utility costs.