Orientation

Building Orientation• Building orientation refers to the way

a building is situated on a site and the positioning of windows, rooflines, and other features.

• It is the practice of facing a building so as to maximize certain aspects of its surroundings, such as street appeal, to capture a scenic view, for drainage considerations, etc. 

The Sun’s True Position• The Sun rises in the east and

sets in the west, but, if this were true, building orientation would be a fairly simple matter.

• In reality, the sun rises and sets in the east and west only on the autumnal and vernal equinoxes (March 20 & Sept 23), and something very different happens during the remaining 363 days of the year.

• The Earth’s tilt causes the Sun to rise and set slightly south of east and west in the winter, and slightly north of east and west in the summer. 

• This slight angle depends on the time of year and the observer’s distance from the equator.

The Sun’s True Position

• As a result, the winter sun spends all of its time in the southern sky, and the summer sun spends much of its time in the northern sky.

• In the Southern Hemisphere, all of these directions are reversed.

The Sun’s True Position

Why Orientation?• Plan carefully the orientation of the

building to the sun, wind and breezes. • Plan carefully its siting and shape. • Wrong decisions will make the building

less comfortable and downright energy-inefficient.

• It will never be environmentally-friendly and the energy bills will be more, over its lifetime.

Major Climate Zones• Cold or moderate climate - the

site should provide direct sunlight and protection from freezing winds,

• Hot climate - the site should be able to provide shade and sun protection.

Hot and Dry Climatic Zones• This climatic condition generally occurs at latitude

between 15 degrees to 30 degrees on both the hemispheres.

• Maximum day time summer temperature goes as high as 45 degree centigrade and relative humidity as low up to 20 %.

• This type of climate is experienced in areas far from sea coasts and do not receive heavy rainfall. Thus, the humidity is very low.

• So, the buildingsin this climatic zone should be orientated based on solar point of view so that the building receives maximum solar radiation during winter season and minimum radiation during summer season.

Desirable features of buildings in hot and dry climatic zones

• Orientation of building– Non-habitat rooms can be

located on outer faces to act as thermal barrier.

– Longer walls of building should face North & South so that the building gets minimum solar exposure.

– Preferably the kitchen should be located on leeward side of the building to avoid circulation of hot air and smell from the kitchen.

• Windows and Openings in Walls – Windows and large openings in walls with

heavy shutters should be provided on northern and western faces as light coming from north is always diffused and indirect.

– Also direction of breeze, which is from west at most of the places, enters from opening on west side. Windows area should be 15 to 20 percent of floor area.

Desirable Features (Cont.)

• Windows and Openings in Walls– Internal courtyard caters for cross

ventilation & thermal buffer. – Suitable radiation barriers in the form of

canopies, chhajjas, long verandahs etc. should be provided on the West side of the building.

– Sufficient number of ventilators close to the bottom of slab should be provided for hot air to escape the room.

Desirable Features (Cont.)

• Orientation of Walls– Thickness of wall plays an important role

in heat insulation of building. Thicker outer walls are preferred as it behaves as an insulating barrier.

– Painting of walls from outside also plays an important role. Walls with light and shining paints on outer surface have good reflective quality and do not absorb heat.

Desirable Features (Cont.)

•Orientation of Walls– The surface of walls should be

smooth and non-dust catching type.

– Walls constructed with hollow blocks / bricks and Cavity Walls can also be provided as they provide very good thermal insulation.

Desirable Features (Cont.)

• Insulation of Roofs– Roofs should be built up with good

insulating material having slope in windward direction and which reflects the radiation and does not absorb heat.

– False ceiling can be used to improve thermal performance of building.

Desirable Features (Cont.)

• Insulation of Roofs– Terracing should be provided on the flat

roof with mud phuska, lime concrete, foamed concrete or burnt clay block paving over roof slab.

– Top roof surface should be made reflective by providing whitewashing or any reflective paint.

Desirable Features (Cont.)

•Growing of Vegetation– Large shady trees whose roots do not strain

foundation and basement should be planted near external walls to provide shade.

Desirable Features (Cont.)

•Special Building Orientation Requirements– Outdoor sleeping area for

summer nights preferably is provided. Desert coolers and fans can be used during summer months. Therefore, proper space to provide coolers should be planned in the building.

Cold Climate•Sun Facing Rooms

– In cold and mix climates the main living areas should be located in the sunny side of the house. In other words: they should face the south, in the northern hemisphere (or the north, in the southern hemisphere).

– To avoid overheating during the summer, consider trees planted at a proper distance of the house, and also overhangs and shading devices (awnings, shutters, pergolas).

•Buffer Rooms And Spaces– In cold and temperate climates, locate

infrequently used rooms like garages, bathrooms, stairs and laundry rooms in the non-sunny side of the house. They can act as thermal buffer spaces.

Cold Climate

•East-facing rooms– East-facing rooms can benefit from

morning light and their warming effects, and bedrooms, breakfast rooms and kitchens can take advantage of it, at least in moderate climates.

– There may be also be unwanted heat gains and glare during the summer in east-facing rooms; to prevent it, consider horizontal and low shading.

Cold Climate

•West Facing Rooms– Rooms facing the west will benefit from the

warming sun during the late afternoon, something that can make them appealing spaces in moderate and some cold-sunny climates.

– But like east-facing rooms, west-facing rooms can also be a source of unwanted heat gains and glare, during the late afternoon. Horizontal-low shading can prevent overheating and glare.

Cold Climate

Planning for tree shade• Trees can both provide needed shade on a

balmy summer day and starve the house of natural light when it is needed most.

• Deciduous trees planted on the south side will lose their leaves in the winter and allow natural light to enter the house, while evergreen trees planted on the north and west side will provide shade from the summer sun.

• The age, species, growth rate and mature canopy cover of existing trees should be carefully considered before deciding where to orient a structure on a building lot.

Driveways• Driveways and parking lots are made using gravel

and asphalt – materials that heat up faster and reach higher temperatures than the rest of the yard.

• Excessive heat there can spill over to the adjacent house, which is why placement of the driveway or parking lot to the south or east of the building can reduce summer heat buildup in southern climates.

• During the cold winter months in northern climates, a south- or west-oriented driveway will melt snow faster and provide the home with greater warmth.

• Prevailing winds - the winds that blow predominantly from a single, general direction over a particular point.

• Data for these winds can be used to design a building that can take advantage of summer breezes for passive cooling, as well as shield against adverse winds that can further chill the interior on an already cold winter day, or even prevent snow from piling up against windows and doors.

Orientation as per Winds

• Detailed information about prevailing winds - usually available from airports, larger libraries, Internet sources, and county agricultural extension offices, etc.

• As a general rule of thumb, cold winter winds generally come from the north and west, which can be limited by using insulating glazing on these sides of the house.

• The coastal areas typically experience breezes from an onshore direction, while cool breezes flow down valleys from mountain slopes.

Orientation as per Winds