Passive heating utilizes building design and orientation to heat buildings without energy consumption. It works by allowing sunlight to enter through apertures like windows, where it is absorbed by dark surfaces and transferred to thermal mass materials that store the heat. Common passive heating techniques include direct solar gain, thermal mass walls, and Trombe walls, which use glazing, high mass materials, and solar orientation to collect, store, and distribute solar heat within a building. Apertures, shading, and other design elements must be implemented intelligently to take advantage of winter sunlight while avoiding overheating in summer months.
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Passive Heating
2. Passive heating :
-refers to technologies or design features used
to heat buildings without power
consumption.
-building design attempts to integrate the
principles of physics into building exterior
envelope to:
*speed up heat transfer into a building
4. Aperture- the large glass area, usually a window, through
which sunlight enters the building. Typically, the aperture
faces within 30 degrees of true south and should avoid being
shaded by other buildings or trees between 9 a.m. to 3 p.m.
each day during the heating session
Absorber- a hard, darkened surface of the storage element,
is the second element of the design. The surface sits in the
direct path of the sunlight, which hits the surface and is
absorbed as heat
Thermal mass-the materials that retain or store the heat
produced by the sunlight. Unlike the absorber, which is in the
direct path of the sunlight, the thermal mass is the material
below or behind the absorbers surface
5. Distribution- the method by which solar heat
circulates from the collection and storage
points to the different areas of the house
Control- During the summer months, roof
overhangs are used to shad the aperture.
Other elements can be used to control the
under- and/or overheating include electronic
sensing devices, operable vents and dampers,
low-emissivity blinds, and awnings.
6. Direct Solar Gain
Direct gain is the heat from
the sun being collected and
contained in an occupied
space. Direct solar gain is
important for any site that
needs heating, because it is
the simplest and least costly
way of passively heating a
building with the
sun. Avoiding direct solar
gain is also important in hot
sunny climates.
7. Massing and orientation are
important design factors to
consider for passive
heating. Consider these
factors early in the design
so that the surface areas
exposed to sun at different
times of day, building
dimensions, and building
orientation can all be
optimized for passive
comfort.
8. Thermal mass is a
material's resistance to
change in
temperature. Objects
with high thermal mass
absorb and retain
heat. Thermal mass is
crucial to good passive
solar heating design,
especially in locations
that have large swings
of temperature from
day to night.
9. A Trombe wall is a
system for indirect solar
heat gain that is a good
example of thermal mass,
solar gain, and glazing
properties used together
to achieve human
comfort goals
passively. It consists of a
dark colored wall of
high thermal mass facing
the sun, with glazing
spaced in front to leave a
small air space.
10. Windows and other
apertures bring in heat
from sunshine, but can
also lose heat by
radiant cooling and by
conducting heat better
than most wall or roof
constructions. Apertur
es and shading must
be intelligently placed
to take advantage of
the sun's heat in cold
locations and seasons,
while not overheating
in hot seasons.
11. Shades can keep
the heat and
glare of direct
sun from coming
through
windows. They
can also keep
direct sunlight
off of walls or
roofs, to reduce
cooling loads.