Most
temperate climate roofs are a lot darker than white, and the darker they are the more heat they collect. In summer this is either expelled from the attic or
somehow prevented from entering the living areas. Insulation is usually
the solution for the attic floor, walls, and roof just as thermal
windows are the normal solution in the living area to prevent heat loss or
gain.
But it is cheaper and more efficient to stop the heat from
entering or leaving the house in the first place. Heat gain is why
outdoor
window shades were invented at some primitive time. Heat loss is why
thermal windows were invented much later. That's what's great
about the Greenhouse Cap. It allows us to return to the beauty of cheap
and low-tech where the sun shines most - on the roof. Unsophistication
is beautiful!
This also explains the "bedsheets" -- what I call White-sheeting. They are summer flooring of any suitable material for the Cap, to prevent the actual floor of dark concrete pavers (tar might stick and black tile might be slippery) from absorbing the summer heat. White-sheeting is also used and can be especially beautiful on the skylights in summer, reflecting direct sunlight and turning it into a glowing translucence viewed from inside the home. (see photos below) In not-so-hot climates you could use light pastel colors to
co-ordinate with the color scheme in the room below, or if you live in
Scandinavia you might completely leave them off in summer and watch the
clouds instead.
Since any white translucent covers prevent the sun's heat from being absorbed by
the floor they rest on, this makes it possible to have a Cap floor
of totally black dense material, like pavers, for heat
gain during winter when uncovered. Before
now, on the outside of your house, you couldn't practically use sheets or curtains because they would only last maybe
two summers plus they would flap and shred or blow away. The Greenhouse Cap prevents this. Before the concepts of White-sheeting in a Greenhouse Cap, you
could never economically take year around thermal advantage of a black roof and
skylights. Now you can -- winter and summer.
The Greenhouse Cap, adequately weather-sealed in winter, can keep your home warm. Dead air space insulates, and that is what the Cap becomes in winter, a giant thermal window to the sky. In summer, with it's gable windows/ridge vents open and the White-sheeting spread, it can keep your house cool.
The quick winterizing process is as follows: the Cap's outside vents and windows are closed and the White-sheeting is removed from floors and skylights, turning the floor into an instant horizontal trombe surface,
storing heat to use after sundown. In winter, the sunlight comes in the
skylights at a low angle, preventing glare and hot spots, but allowing
magnificent views of the changing sky overhead.
During winter sun hours the uncovered
skylights allow heat gain in the Cap to enter the home while extra heat in
the Cap is blown directly into the home or to the thermal storage
under the home, which is then vented into the home after
sundown. At night the only air movement is from the underhouse thermal
storage into the house. The Cap is a tightly closed air space all night, blanketing
the house.
Normally, enough heat would be
given off at night from thermal mass storage to keep the home
comfortable without covering the skylights. But in the event of a
severe winter
storm with extreme low temperatures, the skylights could be
temporarily insulated with a minimum of work by throwing old blankets
over them (if you're a Luddite). You see, there is a reason for the existence of old
blankets! If
you are instead a techie, then thin insulating panels of White-sheeting, like Kalwall, can be
engineered to fold and latch over the sky lights, even at the push of a button (if you are a techie), like an automatic pool cover.
This Bright Idea thermal system of Greenhouse Cap plus White-sheeting will prove so efficient, that you will be able to enjoy your clear skylights all year round. (By the way, in a flat roof they are much easier to clean from below. Have you ever tried cleaning the inside of a skylight set in a pitched roof ten feet over your head?) The system is lo-tech and flexible, and if you were prepared and needed to get warmer in a cold snap, you could quickly add "old blanket" back-up insulation material to the Cap skylights. Or fire up the old wood-burner.
The
summerizing process goes like this: remove and store any insulating materials
from the Greenhouse Cap floor and skylights. Take your White-sheeting from storage and spread over
your dark roof. You can do the same or not for individual skylights.
Your choice. Even if the Cap end windows are wide open, small clips
on the corners of the sheets would keep them from moving or blowing away. Or you could use grommeted
sheets of some material. Those are lo-tech! Just make sure
they are very light colored and you can see the amount of light you desire through them.
In the hot days of summer when the sun is pouring down on
your house, your skylights will glow with light without letting in
heat. The
Greenhouse Cap allows a pleasant return to a simpler,
much more economical way to keep a home cool and at the
same time full of light in summer, while most of the
winter
it creates warmth, and remains light-filled.
Except for the hottest months
you will have gorgeous clear sky views. As a matter of fact,
it's probably the only reasonable way to accomplish this. Otherwise it
would have been tried before now. Skylights increase our interaction with the changing seasons and allow us to receive daily the soul-restoring influence of natural beauty -- always overhead, but often unnoticed.
The album of Bright Idea Home model views under
the Photos tab at top will give you some ideas of what a completed home
might look like.
The Greenhouse Cap idea can fit itself to just about any home design or
style. I will be designing more models as time allows. I think
they are very elegant and interesting, but then, I'm prejudiced. Tell
me what you think by leaving a message here (buttons below), or you can post under the Posts tab at top.
For
more details on seasonal preparations with a lo-tech Bright Idea
thermal system, go to "Seasonal Details" under the Posts tab. And don't forget to go to the Links tab for the opportunity online to walk-through these same Bright Idea designs in 3D and operate some of the doors, windows, drawers, and even
watch the fish float. You can also use my designs as templates to make
your own! The LINKS tab will give all the details under Favorite Online Design Program (near the bottom). Have fun!
