(b) utilities such as stores can be on

(b) Open Spaces and Built Forms

 Buildings can be clustered together to
minimize exposure to cold winds.

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 Open spaces between buildings must be such
that they allow maximum solar rays to be incident on the building.

 They should be treated with a halt and
reflective surface so that day reflect solar radiation onto the building.

 

(c) Street Width and Orientation

In cold
climates, the street orientation should be east-west to allow for maximum south
sun to enter the building.

The street
should be wide enough to ensure that the buildings on one side do not shade
those on the other side (i.e. solar access should be ensured)

 

 ORIENTATION
AND PLANFORM

Buildings
must be compact with small surface to volume ratios to reduce heat loss.

Windows
should face south to facilitate direct gain.

The side of
the building which is facing north should be well insulated so that it is not
affected easily

Living areas
can be located on the southern side while utilities such as stores can be on
the northern side.

Air-lock
lobbies at the entrance and exit points of the building reduce heat loss.

Heat
generated by appliances in rooms such as kitchens may be used to heat the other
parts of the building.

 

 BUILDING ENVELOPE

(a) Roof

False
ceilings with internal insulation such as polyurethane foam (PUF), wood wool,
etc. are feasible for houses in cold climates.

Aluminium
foil is generally used between the insulation layer and the roof to reduce heat
loss to the exterior. A sufficiently sloping roof enables quick drainage of
rain water and snow.

A solar air
collector can be incorporated on the south facing slope of the roof and hot air
from it can be used for space heating purposes.

Skylights on
the roofs admit heat as well as light in winters.

Skylights can
be provided with shutters to avoid over heating in summers.

 

(b) Walls

Materials
that lose heat slowly can be used for the construction of walls.

The
south-facing walls (exposed to solar radiation) could be of high thermal
capacity (such as Trombe wall) to store day time heat for later used.

The walls
should also be insulated.

The
insulation should have sufficient vapor barrier (such as two coats of bitumen,
300 to 600 gauge polyethylene sheet or aluminum foil) on the warm side to avoid
condensation.

Light weight
and hollow concrete blocks of recent trends can be used.

Skylights can
be provided with shutters to avoid over heating in summers.

On the
windward or north side, a cavity wall type of construction may be adopted.

 

(c) Fenestration

In order to facilitate
direct heat gain it is advisable to have the maximum window area on the
southern side of the building.

They should
be sealed and preferably double glazed to avoid heat losses during winter
nights.

 Condensation in the air space between the
panes should be prevented,

 Movable shades should be provided to prevent
overheating in summers.

 

(d) Color and Texture

The external
surfaces of the walls should be dark in color so that day absorbs heat from the
sun.

 

 TECHNIQUES

(a) Glazing
South facing glazing is ideal for cool temperate climates. It allows maximum
solar access in winter and can be easily shaded in summer. In cool temperate
climates

Maximize
South facing glazing with solar exposure (especially in living areas). See:
Passive       Solar Heating

 Minimize east & west facing glazing.

 Use adjustable shading. Insulating glass unit
with low-e

 Use insulating glass and frames and/or snug
fitting insulating drapes with sealed pelmets.

 (b)Trombe Wall

 A Trombe wall is a thermally massive wall with
vents provided at the top and bottom. It may be made of concrete, masonry,
adobe, and is usually located on the southern side (in the northern hemisphere)
of a building in order to maximize solar gains

The outer
surface of the wall is usually painted in dark shades for maximizing absorption
and the wall is directly placed behind the Glazed area with an air gap in
between.

Sun light or
the solar radiation is absorbed by the wall during the day and stored as
sensible heat. The air in the space between the glazed area and the wall gets
heated up naturally which then enters the living spaces by convection through
the vents.

Cool air from
the rooms replaces this air, thus setting up convection current. The vents are
closed during night, and heat stored in the wall during the day heats up the
living space by conduction and radiation.

In cold
regions of India namely Leh the usage of trombe walls can be seen extensively.

It is a
notable fact that in buildings with thermal storage walls, the temperature in
door can be maintained at about 150Co when the outside temperature
is as low as -11 Co.

Generally,
thickness of the storage wall is between 200 mm and 450 mm, the air gap between
the wall and glazing is 50-150mm, and the total area of each row of vent is
about 1% of the storage wall area.

The trombe
wall should be adequately shaded for reducing summer gains.

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