Thursday, June 18th, 2020 by Erin Dougherty
Many homeowners in our area experience rooms that are too hot in the summer and too cold in the winter. Some never want to use these spaces or implement band-aid fixes such as space heaters and additional fans to circulate air just to make the space bearable when they cannot completely close it off. Piling on layers of clothing or blankets on should not be the norm in your home, where you should be comfortable. Many homeowners just deal with this, thinking, it is how things are and there is nothing more they can do.
What is causing our homes to be uncomfortable, driving up our energy bills, and making our heating and cooling units work harder with no results? More often than not, it isn’t the result of an HVAC unit that’s improperly sized, but the result of conditioned air and heat being lost to your unconditioned attic space as well as heat radiating down to the rooms below.
This attic, like many others, houses the HVAC equipment including ductwork. This leaves the ductwork subject to the extreme temperatures of the attic, making the home harder to heat and cool. In the summer, the attic is hotter than it is outside, and so is everything in it. The metal duct lines are scarcely insulated and heat up to the same temperature as the attic, including the air inside of them. When we try to pump cold air through the lines to rooms that are too warm, the cool conditioned air is warmed up by the hot duct lines and the air inside them, delivering significantly warmer air into rooms you’re trying to cool.
This does not occur because your HVAC system is necessarily inefficient, but because the ductwork is living in hostile conditions. When there is little insulation on the floor of the attic, the heat transfers to the ceiling and then radiates into the rooms below making them hotter and even harder to cool down. Depending on where the thermostat is located this could mean that your heating and cooling system is running all the time, racking up your energy bills, leaving you uncomfortable, and adding wear and tear to the unit. Or, it is not running enough because it is located in one of the rooms that can reach the temperature you want, so the rooms that are too hot aren’t being conditioned enough.
It is a vicious cycle that many homeowners battle. Some homes have an attic fan installed. The idea is that these fans will pull the heat out of the attic, which they do. However, the problem is that when an attic is not properly air sealed and insulated, the attic fan only exacerbates the problem of high energy bills and uncomfortable rooms. Consequently, the attic fan in an unsealed and under-insulated attic amplifies the stack effect and sucks even more conditioned air from the living space into the unconditioned attic.
So, what can be done to make you more comfortable in your home, reduce your energy bills, and reduce the wear and tear on your HVAC equipment? Air sealing and Insulating the attic is the best way to address the air loss and heat transfer impacting your home and your comfort.
This can be approached in a few different ways. The first is by removing or pushing aside the existing insulation and air sealing then installing an R-38 to an R-49 of insulation. There are hundreds of holes connecting your conditioned space to your unconditioned attic such as top plates, can or recessed lighting, utility penetrations, bath fans, and even access doors. Since attics need to be vented to protect the roof, we have soffit and ridge vents that allow air to flow through, pulling more air into the space and the cycle continues. By air sealing, we can reduce the loss of conditioned air at the top of the home.
Keeping conditioned air in the living space longer means the heating and cooling system can run less and you can be more comfortable. However, if we do not add enough insulation to reduce the transfer of heat into the living space below, then we will continue to battle temperatures. Therefore, we want to install an R-39 to an R-49 of insulation depending on how much material is already there. Typically, we use blown-in cellulose insulation for this because it offers a high R-value per inch compared to batt or blown fiberglass. It is also an environmentally friendly material, composed of 85% recycled components and 15% new material. The product used by The Drying Co. also contains a borate solution which has been known to help deter pests. Cellulose can also be blown over duct lines in the attic reducing the impact of the environment on the ductwork. This solution is ideal when homeowners are not using their attic for storage, don’t have ductwork in their attic, don’t plan to finish the space in the future, or may use the space for storage but aren’t worried about humidity.
Another option is insulating from the rafters. This can be done in a few ways, by installing Foamboard or Dense packed cellulose and maintaining the ventilation of the roof with soffit and ridge vents, or by encapsulating the attic with spray foam.
Foamboard insulation can be attached directly to the attic rafters and all the seams are sealed. This leaves ventilation in the cavities between the rafters to protect the roof. It provides some control over temperature and humidity, especially in attics with ductwork or being used for storage. However, this approach does not give the homeowner the option to later finish the attic space or convert it into a conditioned space.
Dense packing the rafters with cellulose requires installing PVs (proper/polystyrene vents) in each cavity to maintain ventilation from the soffit vent to the ridge vent. Then netting is adhered to the rafters and cellulose insulation is packed into each cavity. This option maintains the ventilation of the roof and allows the homeowners to sheetrock at a later date if they choose.
Spray Foam can be installed on the rafters in either open-cell or closed-cell formula. The open cell is porous and allows moisture and air to travel through it. At about 5 inches thick the open-cell foam becomes an air barrier but will never become a moisture barrier.
In contrast, the closed-cell spray foam is an air barrier and vapor retarder at 1.5 inches and is usually installed on attic rafters at about 3-inches offering an approximate value of R-21. This approach eliminates the need for ventilation in the attic. This added structural durability can even protect your roof in extreme weather events such as a hurricane or nor’easter strength winds.
It is important to remember in an approach where the attic is encapsulated, that we need to ensure the relative humidity is controlled. This can be achieved by ducting into the attic, or by installing a dehumidifier, the best approach varies by home.
Insulating from the rafters is a great choice when homeowners want to condition the space, plan on finishing the space, have HVAC equipment in the space and want to bring it into the conditioned space, or want to use the space for storage and regulate the conditions their belongings are stored in.
All these approaches would limit the loss of conditioned air to unconditioned space, keeping the air you paid to heat and cool in your home longer. As a result, this means that the rooms in your home are more comfortable, and temperatures are even throughout the home. This lowers your energy bills and reduces wear and tear on your heating and cooling unit saving you money all around.
If you are uncomfortable in your home, have rooms that are too hot or too cold, or have high energy bills, call the experts at The Drying Co./ThermalTec at 1-757-566-8622. You can schedule a free home energy and insulation evaluation with one of our experienced Home Performance Advisors.