Installing energy efficient doors is one of the most conscious things you can do as a homeowner. Doors and windows are some of the main culprits when talking about your house’s air leakage. This contributes to a loss of energy and a loss of heat in the winter. The condition of your door can contribute greatly to this air leakage. Proper weatherproofing and sealing can help, but if your door itself is not insulated, is insufficiently covering the doorway, or is improperly installed, a new, energy efficient door is in demand.
What to Look for in Energy Efficient Doors
Know Your Labels
The National Fenestration Rating Council (NFRC) and Energy Star both help with comparing energy performance ratings of doors. In order to decide which door to purchase, you will be looking at two main factors: the solar heat gain coefficient (SHGC) and the U-factor.
The SHGC ranges from 0.00-1.00 and specifically measures the about of solar heat that is transmitted through the door; 0.00 being 0% and 1.00 being 100%. For instance, a SHGC rating of 0.38 means door absorbs 38% of the solar heat and reflects 62%. The SHGC should be low. The lower the number, the less heat it will absorb in direct sunlight.
Similarly, the U-factor should also be low. Ranging from 0.00-2.00, it measures the rate of heat transferred between the two sides of the product, in this case, the door.
Other Key Factors
The R-value is another factor to consider when picking out your energy efficient door. This the measurement of thermal resistance. More specifically, it is the measurement of the door’s resistance to conductive heat flow. Rated from 0-5, this number should be high. The R-value is sometimes combined with the U-factor to make reading the stats easier for consumers.
Sometimes called air infiltration (AI), air leakage is exactly what it sounds like – the amount of air that passes through any given building. AI is measured in cubic feet per minute (cfm). The industry standard is 0.3cfm, but ratings differ based on material, construction, and installation. The most important factor of the three is installation. Ensuring your door is installed as securely as possible and with no gaps or spaces between the door and the frame is important to decrease the air leakage. Air leakage accounts for 25-40% of heating and cooling energy usage, so this is important.
Low-E Coatings on Energy Efficient Doors
Low-emissivity coatings, or low-e coatings, are near-invisible layers of metal oxide applied to glass. It helps reduce heat transfer and contributes to a lower U-factor for glass. Some may also help reduce light transmission. Door panes (or any glass products) with low-e coatings will cost a little more, but they help the energy efficiency of the glass to the tune of 30-50%.
All this to say, there’s a lot to consider when choosing a door, and some of it is pretty technical. Johnson Lumber is here to walk you through the process, and to explain all of these factors to you. We can give you options to look at and compare based on efficiency and your personal aesthetic.
We carry quality doors from reputable brands like: