R-value is a measurement used to determine the energy efficiency of both windows and doors; 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.
Want some help choosing a new entry door? Read our article ‘How to Choose an Entry Door’ for lots of photos ideas and help to choose a style and colour. Or see some recent door and window installations here.
Solid Wood Doors:
Solid wood doors are both a classic and contemporary choice, possibly the most well-known material when one thinks of ‘door’. However, it just so happens that wood doors have some of the lowest R-values, and so by themselves, are very poor insulators. The wood itself absorbs heat and consequently allows for its transfer. This changes depending on the thickness of the wood, however as a rule wooden doors have the lowest R-value.
Fibreglass and Vinyl:
Both vinyl and fibreglass doors share a similar quality that allows them to be relatively energy efficient. Fibreglass, unlike wooden doors, does not absorb heat very well, and so acts as a natural barrier that prevents the outside temperature from entering your home. Both products are heat malleable; they can be stamped to appear to have wood grain and raised panels. Both fibreglass and vinyl doors have a wood frame core and solid foam insulation resulting in high R-values and are a better insulative choice than wooden doors.
Although steel is an excellent temperature conductor, they are surprisingly capable insulators of hot and cold energy when filled with the same high R-value core as fibreglass and vinyl doors. The distance between the core and the two metal sides makes it very difficult for heat to transfer through properly. 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 through the frame.
Glass doors are one of the least energy-efficient components of a door, following the inefficiency of wooden doors. In fact, glass sliding doors (patio doors) are not even considered doors in themselves, but instead are referred to as large windows. Glass as a material is not a good insulator considering it lets in a lot of outside elements naturally. Most glass door manufacturers use double-glazed units (two panes of glass with an air gap between) filled with a compressed gas that prevents the transfer of temperature.
Read our article ‘Signs That You Should Replace Your Exterior Door’.
All weatherstripping wears out but is easy to replace.
Weatherstripping is a product used to seal both windows and doors in order to prevent the intrusion of outside weather and to reduce energy loss. The materials used are varied; fibreglass, rubber, foam, and specific metals like brass and aluminum. Weatherstripping can be found at local hardware stores and can renew the R-value and prevent drafts of your current windows and doors. In addition, a weatherstrip sweep attached along the bottom of a door prevents air movement and adds insulation.