Windows and Doors

I have two main entrance doors to the house and twelve windows of varying sizes. The south wall has seven windows. Six of these windows are 1.75 meter in height by 1.15 m in width and are fixed - non-operable. The last central window is also 1.75 by 1.15 but is an operable two-paneled casement window. Each of the three bedrooms has a 1.20 by 1.20 m operable two-paneled casement window with built-in manually-operated roll-down insulated exterior curtains. One of these is on the west wall, another on the east wall and another on the north wall. The two bathrooms have small 50 by 50 cm one-paneled operable casement windows; both of these windows are located on the north wall. All windows are made of double-paned, low-e glass with moisture-absorbing aluminum spacers and insulating, high-quality white PVC frames. The two entrance doors are 2.25 m in height by 90 cm in width and located at opposite ends of the 17 long south wall. They are made of aluminum-reinforced, insulated PVC 'sandwich' panels - central metal core with a layer of insulation on each side and enclosed with PVC surfaces. The windows and doors have very good thermal and acoustic insulation properties in relation to the Spanish average. They were joined to the walls by using expanding polyurethane foam in order to provide a strong, waterproof, well-insulated and air-tight connection.

These windows have been designed, sized and placed in accordance to ventilation, daylighting and passive solar (cooling) design principles in order to exploit the energy of the sun and wind to regulate the internal house climate, light levels, and air quality. In accordance with passive solar principles, numerous and large windows are placed on the south-facing wall in order to exploit the winter sun for interior space heating. Few and smaller windows are placed on the east and west walls in order to avoid summer overheating, and these windows have built-in roll-down insulated curtains that further help block early morning and late evening summer sun that can cause overheating. Few windows are placed on the north wall as these can not take advantage of the sun to heat the interior and simply act as net losers of heat energy in winter; they are also impacted by cold winter northerly winds, which further cause them to lose heat. For these reasons the north bedroom window has a built-in roll-down insulated curtain and the bathroom windows are extra small. Enough glass surface area is established to maximize solar radiation capture but not so much glass as to cause winter daytime overheating and excessive night-time heat losses. Glass surface area was balanced in relation to thermal mass - the more thermal mass available, the more glass surface that can be allowed and vice-versa. All of the windows are either fixed or casement in order to achieve greater insulation. Fixed windows are better than operable windows in insulation terms because they have less framing, which is often less insulating than the central insulating glass, and because they air air-tight. Casement windows (the ones that open and close like normal doors), meanwhile, can provide better air seals, and therefore be more air-tight, than sliding windows. Using windows and doors with good thermal insulation helps minimize heat and cool losses in winter and summer, helping to minimize needed energy resources. Triple-paned windows are even more insulating but significantly reduce solar radiation capture and are therefore more appropriate in climates where greater energy-efficiency benefits are achieved by maximizing insulation levels rather than by maximizing solar energy capture, such as regions closer to the poles.

In accordance with passive cooling principles, there are a number of operable windows strategically placed throughout the house. There is one large operable window in each of the walls. These south and north wall windows are centrally placed. The placement and size of these operable windows permits me to channel wind breezes in a multitude of ways throughout the house. The fact that the windows have two panels allows me to increase or decrease the flow of these breezes within the interior by opening just one or both; furthermore, the operable curtains allow me even greater control of the flow of these breezes. Roll-down mosquito netting frames were placed on these windows so that they can be freely opened without worry of insect and bird invasions. The mosquito netting on the east and west wall windows helps prevent summer overheating of these bedrooms by acting as shade cloth. Use of these operable windows to establish cooling wind breezes within the home are only appropriate when the exterior air temperatures are only slightly higher than the interior; otherwise, the hot breezes simply bring in hot air, maxing out the thermal mass and equalizing the cooler interior temperatures with those of the hot exterior. When there are large differences between hot outside air and cooler interior air, keeping well-insulated and shaded windows closed rather than open provide greater cooling benefits. The doors and windows are a shiny white to help reflect away excess solar heat.

In accordance with daylighting principles, each room has an adequately sized window. The large open kitchen-living-dining room area has much glass space, whereas the small six meter square bathroooms, rooms used infrequently, have small windows. The size and placement of the windows, coupled with the home's relatively open floor plan, enable light to penetrate from all walls and spread fairly uniformly throughout the house, from early in the morning to late in the evening.

In accordance with ventilation principles, each room has an operable window. This enables each and every room to be quickly and easily aired out to replace interior air that has become bad for whatever reason with fresh outdoor air. The large south wall operable window is situated in front of the masonry stove and kitchen cooking area in order to be able to quickly exhaust any smoke, carbon monoxide, excess humidity or other noxious gases that may accidentally occur. The small bathroom windows are located near the top of the wall to facilitate water vapor release when excessive humidity is produced due to hot showers and baths.

Both house entrance doors are located at opposite ends of the south wall. This is for two reasons. These doors provide direct access to the main living areas of the house, the combined entrance-living room-kitchen-dining room open area. And, secondly, I plan to build a sun room that covers the entire south wall which will act not only to provide extra solar heating for the house but also as a large airlock entry for these two entrances. Furthermore, I am considering incorporating a specially designed and built second door at each entrance so that it is necessary to open two doors to enter/exit - these second doors will provide greater insulation and will be designed so that they also help provide extra solar radiation into the house and increased ventilation and air breeze manipulation.

When designing my home, I originally leaned toward wooden window frame construction because it is renewable and safe (and sometimes sustainable and local) but ended up deciding against it and for PVC instead for several reasons. While both provide good thermal and acoustic insulation characteristics, wood is not a reliable construction material if exposed to the elements. It can burn - being located in a forested area in a country afflicted with increasingly frequent and large forest fires, wood seemed a risky choice. At the very beginning of house construction a large local forest fire burnt a fourth of my property, including the areas directly around my storage structure, well tower and house; the brick structures and AAC building material were unaffected, but the wooden palets on which sat the AAC blocks burnt away as did a number of outdoor wooden furniture pieces. Whereas the PVC chairs that were relatively close to the wooden ones did not burn. Wood also does not hold up well to Spain's intense sun. The sun's radiation has a strong negative impact on wood. Some of my closest neighbors are (were) a group of Buddhists owning a four hectare property with a number of wooden cabins. The cabins (that remain - one structure burned down from a cooking gas explosion, one from the forest fire that burned part of my property and their wooden temple from a lightning strike) have been there less than ten years; I have witnessed the steady deterioration of these wooden structures and that of their window frames due, primarily but not exclusively, to the sun's radiation. The window frames and doors now have numerous cracks and imbalances that have created numerous points of difficult-to-remedy air leakage. Needless to say, this Buddhist center is now basically abandoned except for one individual who lives is a puny all metal structure and one other who bought his own chunk of nearby land and built a tiny cabin out of AAC and PVC windows (admittedly I helped design and build this Buddhist monk's cabin). Furthemore, wood is negatively affected by rain and humidity. Here in Spain a window is exposed to both in winter; the rains wet the exterior and the winter cold causes moisture condensation on interior window glass surfaces that drips onto the frame. Frequent, excessive moisture leads to wood frame deterioration through repeated expansion and drying and through rot. Insects can also be a serious wood problem in many areas. In my area there are no termite problems (that I have been made aware of), but there are several other types of insects, in particular several types of caterpillar/worms, that can eat tunnels through wood structures. Of course, all of these problems can be eliminated through judicious maintenance of the wood structures with appropriate surface treatment paints. The problem with this is that a maintenance schedule must be maintained by people who may or may not have the time, money, patience or desire to do this regular maintenance. And how much maintenance is required depends greatly on the location; here in central Spain maintenance requirements are exorbitant. Much more northerly locations that have less intense sun, less moisture problems (due to more snow and less rain and a reduced number of much-better insulated windows), and fewer possible perjudicial insect infestations are more appropriate for wooden window frames due to less daunting maintenance requirements.

Well-made PVC frames, on the other hand, require no maintenance, other than occasional cleaning with some water and soap, since they are not affected by the sun, moisture or insects/microbes. They, therefore, have a very long lifespan. They also are basically inflammable since extremely high temperatures are required to alter them, making them more acceptable in risky forest fire areas. Some other environmental benefits are that these frames produce little to no waste in production and any waste is completely recyclable. Energy requirements for production are relative low. The two primary material resources of PVC window frames are salt at around 57%, with salt being a widely abundant resource, and petroleum at 43%. Unfortunately, petroleum use is highly questionable as it is definitely a problem resource - nonrenewable, nonsustainable, nonlocal. Also, PVC is claimed to release toxic gases into the air during production and under certain circumstances such as burning; I do not know the specifics of such claims since I have not looked into them, but I trust Greenpeace (I am paying member). If they say this stuff is bad and needs to be reduced or phased out, then I will take steps to reduce my use of the stuff. If I had to choose new windows today, I might instead go with the new fiberglass frames that are starting to be marketed. Of course, costs have to be kept in consideration since fiberglass is fairly expensive compared to PVC, so I would need to balance the loss of finances for fiberglass windows with what I that extra money could have otherwise enabled me to do, such as buy extra PV panels for example. Figuring out the right green thing to do is rarely simple.