BUILDING ORIENTATION IN WARM AND DRY CLIMATE

Orientation of building should be done for the climatic zone in which the building is situated. The purpose of orientation is to provide residents a comfortable living space throughout the year even under severe undesirable weather conditions. Here we will discuss about orientation of building for maximum comfort under hot and dry climatic conditions.

Hot and dry climatic zones: Hot and dry climatic zones generally occur at 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 buildings in 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 are:

1. Orientation of building: Orientation of building in this climatic zone should be such that 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.

2. 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. 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.

3. 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. 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.

4. 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. 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.

5. Growing of Vegetation: Large shady trees whose roots do not strain foundation and basement should be planted near external walls to provide shade.

6. 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.

GUIDLINES FOR CIVIL SITE ENGINEERS

Following are few general points to remember for civil site engineers to make the construction work easier while maintaining quality of construction:

• Lapping is not allowed for the bars having diameters more than 36 mm.
• Chair spacing maximum spacing is 1.00 m (or) 1 No per 1m2.
• For dowels rod minimum of 12 mm diameter should be used.
• Chairs minimum of 12 mm diameter bars to be used.
• Longitudinal reinforcement not less than 0.8% and more than 6% of gross C/S.
• Minimum bars for square column is 4 No’s and 6 No’s for circular column.
• Main bars in the slabs shall not be less than 8 mm (HYSD) or 10 mm (Plain bars) and the distributors not less than 8 mm and not more than 1/8 of slab thickness.
• Minimum thickness of slab is 125 mm.
• Dimension tolerance for cubes + 2 mm.
• Free fall of concrete is allowed maximum to 1.50m.
• Lap slices not be used for bar larger than 36 mm.
• Water absorption of bricks should not be more than 15 %.
• PH value of the water should not be less than 6.
• Compressive strength of Bricks is 3.5 N / mm2.
• In steel reinforcement binding wire required is 8 kg per MT.
• In soil filling as per IS code, 3 samples should be taken for core cutting test for every 100m2.

Density of Materials:

Material	Density
Bricks	1600 – 1920 kg/m3
Concrete block	1920 kg/ m3
Reinforced concrete	2310 – 2700 kg/ m3

Curing time of RCC Members for different types of cement:

Super Sulphate cement: 7 days

Ordinary Portland cement OPC: 10 days

Minerals & Admixture added cement: 14 days

De-Shuttering time of different RCC Members

RCC Member	De-shuttering time
For columns, walls, vertical form works	16-24 hrs.
Soffit formwork to slabs	3 days (props to be refixed after removal)
Soffit to beams props	7 days (props to refixed after removal)
Beams spanning upto 4.5m	7 days
Beams spanning over 4.5m	14 days
Arches spanning up to 6m	14 days
Arches spanning over 6m	21 days

Cube samples required for different quantity of concrete:

Quantity of Concrete	No. of cubes required
1 – 5 m3	1 No’s
6 - 15 m3	2 No’s
16 – 30 m3	3 No’s
31 – 50 m3	4 No’s
Above 50 m3	4 + 1 No’s of addition of each 50 m3