Heat
By Paul D.Leif
(This is the first of a series explaining how we, as
builders, deal with the forces, energy, and mass of your
new home to create a safe and comfortable abode for
your family.)
When you think of energy, you probably think of
electricity or gasoline. However, this form of energy is
small compared with the energy coming from the sun in
the form of heat and light.
The sun’s heat and light is essential to life on the Earth.
However, we humans are comfortable within a very
narrow range of temperature. One of the main functions
of your home is to control that temperature range.
As architects and builders we must design your home so
that it deals efficiently with the heat from external
sources i.e.the sun, and with the heat generated within
your home, e.g. from people, cooking, and lighting. Yes,
people create heat too. The average person gives off
the heat of a 75 watt bulb.
How we deal with external sources
The sun heats your home by direct and reflected
radiation (sunlight), and by heating air that comes into
your house.
Your roof system is your most important barrier to direct
sunlight. The roofing material must either reflect the
heat or act as a thermal barrier (insulator). The best
roof for reflecting is a white metal roof. However, it
seldom is the best looking roof or the best protection
against typhoons, so we make compromises. We use
asphalt/fiberglass shingles for beauty and rain
protection, but then we must use heavy duty roof
insulation to keep the heat out
Concrete Hollow block walls with re-inforcing bars
(rebars) make very strong walls. Unfortunately, they
have a characteristic called high latent heat. This means
that they soak up the heat during the day and radiate it
into the house at night. This is why your house is
warmer inside than the outside at night. We can fight
this effect with light colored siding on the outside and
with plants that shade the wall. On the inside, we can
use insulating panels and gypsum wall board. Of course
this adds to the construction cost, but it means a much
more pleasant house to live in. Also, if you plan to use
air-conditioning in several rooms, the energy savings
may compensate for the added cost in a short time.
Landscaping can save you money
Plants not only can shade the wall and windows, they
can also directly lower your air-conditioning bill if your
air-conditioner is in the shade of a tree.
An air-conditioner takes the heat out of the house and
carries it outside. The heat exchanger coils on the
outside of your air-conditioner cool more efficiently if the
air around it is cool. The shade from a tree makes the air
around the coils cooler. This makes the unit more
efficient. It cools better and saves you money.
By the same logic, putting air-conditioners close to each
other is a very bad idea. It creates a hot micro-climate
around the units that lowers effciency greatly. This
means that your units work harder and cool less. Only
Meralco will be happy with this situation.
We haven’t talked about windows yet. Windows let in
the light that we need, but they also let in the heat
radiation. There are now clear films and coatings, e.g.
indium-tin oxide (ITO) to keep out the heat (infra-red
radiation). Of course you can just use window coverings
(drapes), but the house may become too dark for your
daytime activities. The use of clerestory windows (high
windows near the ceiling) can allow in-direct light
without letting in the hot and harsh direct sunlight. Also,
it is important that, whenever practical, we design your
home so that you don’t have a lot of exposed windows
on the west and south sides. Again, landscaping is
important here.
This is all we need to say about heat for now. See you
next issue.
