A Door is a Gateway-
Doors are not only the entrance way into a home; They also act as a kind of barrier which prevents the unwanted entry of people, animals, and the outdoor climate. In other words, doors are not just the aesthetic centerpiece, as the designs often do not reflect the true cost-efficiency/ utility that comes with a doors ability to conserve energy. The importance of well-designed doors in modern homes cannot be understated, as the energy efficiency of an entry level door is just as important as the insulation in walls. Various factors play into this, namely the material of the door, the presence of glass, and siding which also helps protect against energy loss.
R-value is a measurement used to determine the energy efficiency of both windows and doors. By energy efficiency, it is described as the ability of a barrier to prevent the transfer of heat. In other words, R-value is just a measurement of how well a material can insulate and contain heat energy. This measurement is used to evaluate the efficiency of different door materials, and thus whether it is appropriate for a particular situation.
Solid Wood Doors-
Solid wood doors are the most antiquated and classic choice, possibly the most well-known material when one thinks of ‘door’. Wooden doors can be made in various styles (more modern or resembling historical creations) which is a significant quality people strive for in some scenarios. However, it just so happens that wood doors have some of the lowest R-values, and thus by themselves, are very poor insulators. The problem is due to the wood material itself, which can absorb heat, and consequently allow for it to transfer. This of course changes depending on the thickness of the wood present, however as a rule pure wooden door have the lowest R-value.
Fiberglass and Vinyl-
Both vinyl and fiberglass doors share a similar quality that allows them to be relatively energy efficient. Fiberglass, unlike wooden doors, cannot absorb heat nearly as well, and thus acts as a natural barrier which prevents the heat from outside seeping in, or vice versa. Similarly, vinyl varies the same poor heat absorption properties, while also having the ability to be ‘hollowed’ out and filled with additional insulative products. This is why vinyl doors are some of the most popular types on the market, due to their malleability. Both fiberglass and Vinyl have high R-values, and thus are a better choice than plain wooden doors if conserving heat is needed.
Steel doors are surprisingly capable insulators of hot and cold energy, despite seeming to be a large hunk of metal. This of course is not the case, as there is a secrete composition like in the vinyl door which makes steel such a good insulator. Steel doors are usually comprised of thin steel plates wrapped around/ filled with a high R-value core. In other words, the distance between the core and the two metal sides makes it very difficult for heat to transfer through properly, despite metal being a great conductor. In this way the door itself will remain quite stable but touching the actual metal will cause you to feel the stored energy unable to pass the frame.
Glass doors are one of the least energy efficient types of doors following the standard un-modified wooden door. In fact, glass sliding doors (patio doors) are not even considered doors in themselves, but instead are referred to as large windows. In any case, glass as a material is not a good insulator considering it lets in a lot of outside elements naturally (think of concentrated sunbeams). To counter this, some manufacturers will use thicker glass, and add siding/ weatherstrippers/ coatings along the sides for additional insulation aids.
Weatherstripping is a mandatory material used to seal both windows and doors in order to prevent the intrusion of outside weather, and to reduce energy loss of course. The material for this accessory varies from fiberglass (same reason as stated above), rubber, foam, and specific metals like brass and aluminum. Many weatherstripping can be found at local hardware stores like Canadian tire and can be added to new/ existing doors in order to beef up the R-value of your doors. In addition to this, most homes come with a ‘threshold’, or the part at the bottom of the door which sticks out just enough to completely stop it when closed. This door-jam in combination with weatherstripper creates excellent insulation, so be sure that this element is included as well.
With this in mind, it is possible to choose the most energy-efficient door material for your specific climate. Even if you’re stuck with a material that seems unsatisfactory, then it is still possible to further insulate most entry-ways with weather-stripping and other insulators.