It turns out that people are most comfortable when they receive radiant heat at a slightly higher temperature than the temperature of the air around them. The two most primitive examples of this situation are: (i) Outdoors, on a spring day when the air is not too hot but the sun is shining. (2) Around an open fire, on a cool evening.
Most people will recognize intuitively that these are two unusually comfortable situations. And in view of the fact that we evolved as organisms in the open air, with plenty of sun, it is not surprising that this condition happens to be so comfortable for us. It is built into our systems, biologically.
Unfortunately, it haffens that many of the most widely used-heating systems ignore this basic fact.
Hot air systems, and buried pipes, and the so-called hot water “radiators” do transmit some of their heat to us by means of radiation, but most of the heat we get from them comes from convection. The air gets heated and warms us as it swirls around us. But, as it does so it creates that very uncomfortable stuffy, over-heated, dry sensation. When convection heaters are warm enough to heat us we feel stifled. If we turn the heat down, it gets too cold.
The conditions in which people feel most comfortable require a subtle balance of convected heat and radiant heat. Experiments have established that the most comfortable balance between the two, occurs when the average radiant temperature is about two degrees higher than the ambient temperature. To get the average radiant temperature in a room, we measure the temperature of all the visible surfaces in a room, multiply the area of each surface by its temperature, add these up, and divide by the total area. For comfort, this average radiant temperature needs to be about two degrees higher than the air temperature.
Since some of the surfaces in a room (windows and outside walls), will usually be cooler than the indoor air temperature, this means that at least some surfaces must be considerably warmer to get the average up.
An open fire, which has a small area of very high temperature, creates this condition in a cool room. The beautiful Austrian and Swedish tiled stoves also do it very well. They are massive stoves, made of clay bricks or tiles, with a tiny furnace
 |
| Austrian tiled stove. |
IO79
in the middle. A handful of twigs in the furnace give all their heat to the clay of the stove itself, and this clay, like the earth, keeps this heat and radiates it slowly over a period of many hours.
Radiant panels, with individual room control, and infrared heaters hung from walls and ceilings, are possible high technology sources of radiant heat. It is possible that sources of low-grade radiant heat—like a hot water tank—might also work to very much the same effect. Instead of insulating the tank, it might be an excellent source of radiant heat, right in the center of the house.
Therefore:
Choose a way of heating your space—especially those rooms where people are going to gather when it is cold— that is essentially a radiative process, where the heat comes more from radiation than convection.
 |
| surfaces slightly warmer than air |
If you have followed earlier patterns, you may have rooms which have a vaulted ceiling, with a steeply sloping surface close to the wall, and with the major ducts behind that surface— floor-ceiling vaults (219), duct space (229). In this case, it is natural to put the radiant heating panels on that sloping surface.
But it is also very wonderful to make at least some part of the radiant surfaces low enough so that seats can be built round them and against them; on a cold day there is nothing better than a seat against a warm stove—built-in seats (202). . . .
1080
| 231 DORMER WINDOWS* |
|---|
 |
108 I
. . . this pattern helps to complete sheltering roof (i 17). If you have followed sheltering roof, your roof has living space within it: and it must therefore have windows in it, to bring light into the roof. This pattern is a special kind of window place (180), which completes the roof vaults (220), in these situations.
We know from our discussion of sheltering roof (117) that the top story of the building should be right inside the roof, surrounded by it.
Obviously, if there is habitable space inside the roof, it must have some kind of windows; skylights are not satisfactory as windows—except in studios or workshops—because they do not create a connection between the inside and the outside world—windows OVERLOOKING LIFE (192).
It is therefore natural to pierce the roof with windows; in short, to build dormer windows. This simple, fundamental fact would hardly need mentioning if it were not for the fact that dormer windows have come to seem archaic and romantic. It is important to emphasize how sensible and ordinary they are— simply because people may not build them if they believe that they are old fashioned and out of date.
Dormers make the roof livable. Aside from bringing in light and air and the connection to the outside, they relieve the low ceilings along the edge of the roofs and create alcoves and window places.
How should the dormers be constructed? Within the roof vault we have described, the basket which forms the vault can simply be continued to form the roof of the dormer, over a frame of columns and perimeter beams which form the opening.
The other ways of building dormer windows depend on the construction system you are using. Whatever you are using for lintels, columns, and walls, can simply be modified and used in combination to build the dormer.
1082
231 DORMER WINDOWS
Therefore;
Wherever you have windows in the roof, make dormer windows which are high enough to stand in, and frame them like any other alcoves in the building.
 |
| Frame them like alcoves (179) and window place (180)with GRADUAL STIFFENING (208), COLUMNS AT THE CORNERS (212), BOX COLUMNS (2l6), PERIMETER BEAMS (217), WALL MEMBRANES ( 2 I 8) ? FLOOR-CEILING VAULTS (219), ROOF VAULTS (220) and FRAMES AS THICKENED EDGES (225).Put windows which open wide (236) in them, and make SMALL PANES (239) . . . , |
IO83
| 232 ROOF CAPS |
|---|
 |
IO84
. . . and this pattern finishes the roof cardens ( i i 8) or the roof vaults (220). Assume that you have built the roof vaults —or at least that you have started to build up the splines which will support the cloth which forms the vault. Or assume that you have begun to build a roof garden, and have begun to fence it or surround it. In either case—how shall the roof be finished?
^ «$•
There are few cases in traditional architecture where builders have not used some roof detail to cap the building with an ornament.
The pediments on Greek buildings; the caps on the trulli of Alberobello; the top of Japanese shrines; the venting caps on barns. In each of these examples there seems to be some issue of the building system that needs resolution, and the builder takes the opportunity to make a “cap.”
We suspect there is a reason for this which should be taken seriously. The roof cap helps to finish the building; it tops the building with a human touch. Yet, the power of the cap, its overall effect on the feeling of the building, is of much greater proportions than one would expect. Look at these sketches of a building, with and without a roof cap. They look like .different buildings. The difference is enormous.