1. Passive Design Strategies
ARCH409: BUILDING & ENVIRONMENT
Assoc Prof Dr Noor Hanita Abdul Majid

2. strategies Building orientation
Building organization and spatial layout
Size of openings
Volumes of spaces
Opening details
Opening orientation
Weather protection
Water element
Building materials

3. CLIMATIC DESIGN FOR THE HOT ARID CLIMATE

4. Results from the Architectural Aspects: hot-arid/ semiarid
MORPHOLOGY Introverted building morphology in the form of a courtyard or atrium in many shapes and spatial layout was popular.
DENSITY Medium-compact configuration with internal open space was essential
ARRANGEMENT Close arrangement around the courtyard for the effect of cold air drainage during night time
CIRCULATION Spatially efficient circulation between functional spaces was an important strategy.
ROOF FORM Roofs in the shape of domes and vaults for closed and semi-open spaces were a common feature.
SURFACE Rough building surfaces were applied.
OPENINGS Minimum window areas located, particularly on the west facing facades. Few small windows were used facing the direction of the cooler winds. Wind catchers or scoop in many different sizes, directions and height in relation to specific breeze were used in most regions.
SHADING DEVICE Wooden screens (composite shading devices) were used in the regions where wood was available.
MATERIAL Block and heavy construction materials were used. Some degree of porosity in building material was essential. Lighter weight materials for outdoor structures were employed.

5. Introverted building morphology
courtyard or atrium in many shapes and spatial layout was popular to create a better inhabitable microclimate.
Courtyard is a social space with an environmental function.
The lengthened and narrow form of this court yard, casts enough and needed shadow for this space during summer days.
Net counting the beauty it provides, by shading and increasing relative humidity it helps the comfort condition of yard and is one of the major elements of natural cooling system of the house.
All openings and room entrances ends are the connecting space between all parts of house.
Courtyard of Borujerdiha house, Iran
ORDOS, Inner Monggolia

7. Medium-compact configuration
Compact with internal open space to reduce the structure’s exterior surfaces in proportion to the interior volume, and to reduce the insolation impact.
shape and volume of buildings should be compact: elongated along the east-west axis; (e.g. the optimum shape is 1:1.3) + large, compact building volumes gain less heat.
the optimum shape is that which has a minimum heat gain in summer and the maximum heat gain in winter.
winter = an elongated form is ideal
summer = a square shape
A compact “patio” house type is therefore preferable. Adjoining houses, row houses, and group arrangements (all continuous along the east-west axis), which tend to create a volumetric effect, are advantageous, as are high massive buildings
Lithospheric arrangements (subterranean) are also applicable.
Traditional and imported urban patterns

8. Shading of buildings and building elements by cantilevered construction,
arcades, loggias and high building parts

9. Proper orientation
To allow for sun and wind protection and controlled wind channelling (airflow).
Sun-orientation
Buildings are best arranged in clusters for heat absorption, shading opportunities and protection from east and west exposures. Protection from solar radiation is particularly important during times of excessive heat when there can be a difference of as much as 3°C in air temperature in a building between the best and least favourable orientation.
The larger building dimension should face north and south (generally, west orientation is the worst: high air temperature combined with strong solar radiation) The optimum orientation for any given location has to be determined in order to achieve the most satisfactory distribution of total heat gain and loss in all seasons. At high altitude enough heat gain for passive heating should be possible.
In general, the best orientation is: north-south with 25o south easterly direction
Wind-orientation
Main walls and windows should face the prevailing (cool) wind direction in order to allow maximum cross-ventilation of the rooms.

10. Close arrangement around the courtyard
Close arrangement for the effect of cold air drainage during nighttime was planned and increase daytime cooled spaces. .
      Cooling system of a courtyard house

11. Courtyard house with covered galleries and an
internal pool for evaporation, day and night situation

12. Spatially efficient circulation between functional spaces
                                                                                                       Plan of Dar Lajimi, a courtyard house, Tunis.
Spatially efficient circulation between functional spaces
to reduce the internal circulation, to increase space-efficiency, and to reduce volume and therefore minimise the need for cooling.

13. Using dome & arched roofs instead of flat roofs
Roofs in the shape of domes and vaults for closed and semi-open spaces: To reduce the effect of insolation, to create more shadow and self-shadowing, and to increase contact with the outdoor winds.
the dome shape roofing of buildings in this region has some thermo-physical reasons as well. Due to having convex and unbalanced surface the impact angle of sunbeam on dome and arched roof is different from one point to another, and a part of it always remains in shade during morning and afternoon times, for this reason the curved shape is suitable for releasing and emitting sunbeams and waves during night and it helps to the night cooling.
If the flat roofs are used in hot & dry regions it is usually paved with square shape bricks called paved bricks. These bricks receive the most radiations of sun. Early morning it starts to increase and late afternoon it decreases gradually.
                                                           Example of dome and vault structures

14. As the roof is the most critical part, high solar reflectivity and emissivity for long-wave radiation are essential, as well as thermal insulation and/or adequate time lag. Outside application of insulation is preferable for reasons mentioned earlier, but needs an additional, robust skin which protects the insulation from damage.
The rounded form of a hemispherical vault (dome) has a larger surface area than its base. Solar radiation is thus diluted and re-radiation during the evenings is also greatly facilitated.

15.                                                                                                                                 Roof plan of the Fu'ad Riyad house in Cairo, showing the malqaf, dome, vaults, and fountain, with sectional plan details.
In hot-arid regions the vault, the dome and the flat roof are the traditional roof shapes. The common construction method of today, a 10 to 15 cm exposed concrete is the worst possible solution, because the inner surface temperature can reach up to 60°C, which remains till late in the evening.

16. The flat roof is practical in areas where it seldom rains
The flat roof is practical in areas where it seldom rains. It is also a good reflector and re-radiates heat efficiently, especially if it consists of a solid, white painted material.
High solid parapet walls along the edge of the roof can on the one hand provide daytime shade and privacy, but can have the disadvantage of creating an undesired stagnant pool of hot air. The construction and exact placement of parapet walls should therefore be carefully examined.

17. A separate roof and ceiling are still today less common in hot-arid regions, whereas they are the obvious solution in warm-humid climates. This efficient, but expensive solution (pitched or flat ventilated double roof) contrasts with the traditional form of most desert buildings. However, the sloping roof with wall shading overhangs and a well-ventilated space between roof and ceiling appears to be an appropriate, contemporary solution.

18. Ventilated double roof with heavy ceiling
the material of the roof should be light and the ceiling material should be massive. The air enclosed in a double roof, or between the roof and ceiling, may reach a very high temperature. This can be avoided by ample ventilation of the roof space by openings facing the prevailing breeze. In addition, roofs (slopes) should be orientated towards the prevailing breeze and any obstructions which would prevent the airflow next to the roof surfaces should be avoided.
                                                     Ventilated double roof with heavy ceiling

19. Ventilated double roof with light ceiling
Sloped roofs could also provide cold airflow towards a courtyard. A membrane covering the courtyard in the daytime allows retention of cool air and provides shade, but needs attendance by the inhabitants.
The efficiency of the central courtyard is increased by stretching a curtain across the courtyard early in the morning during the summer months to trap the cool air. In the evening, this is removed to maximize the night radiation potential. .
                                                             Ventilated double roof with light ceiling

20. Rough building surfaces
To decrease heat gain, to increase the contact with air movement, to reduce the exposure of the sun to the surfaces, and to create a more effective cooling.

21. material
wall in hot & dry regions includes mud, mudbrick, stone, brick, mortar, lime and wood.
These materials have thermal resistance, high heat capacity and they absorb the sun radiation by their external surfaces. The microscopic and many pores of the mentioned material, which are filled with air, change them to a material similar to thermal insulator.

22. Buildings in hot-arid zones are traditionally constructed with thick walls and roofs and with very small openings. An internal thermal storage capacity is very important to decrease the temperature variations and to make it possible to profit from an increased night ventilation by “storing the cool of the night until the day” during summer. The best materials are those that do not conduct heat.

23. Heat flow in daytime and at night
Sun-dried earth brick is one of the poorest conductors of heat, partly because of its very low natural conductivity and partly because mud is structurally weak and necessitates thick walls. Yet thick mud bricks are not a perfect means of keeping cool; they retain heat for a long time.
A big thermal mass can keep cool during the daytime and not be too cold at night. High heat capacity walls are essential. The traditional principle is to shelter behind very thick mud walls by day, and to sleep on the roof under a tent at night.
                                                       Heat flow in daytime and at night

24. Increase of contact surface of building with earth
When a building is constructed without any excavation, the contact surface of it with earth would be equal to its area but once the excavation is done the contact size would be increase.
In hot & dry regions to decrease the heat exchange of building with outside air and to provide low-expense and natural cooling and heating, the buildings are constructed in a pile of soil as much as possible.

25. Minimum window
                                                    Malqaf of the Pharaonic house of Neb-Amun, from a painting on his tomb'
Nineteenth Dynasty (c B.C.)
Minimum window areas located, particularly on the west facing facades: To reduce the afternoon direct insolation and indoor glare.
Few small windows were used facing the direction of the cooler winds: To allow some ventilation and avoid glare.
Generally in hot & dry regions windows aresmall and are located in the upper parts of walls just near the ceiling.
Although external walls do not have so many windows there are so many of them on the yard facing internal walls. Cross ventilation is done by these windows.

26. Openings and windows
necessary for natural lighting and ventilation, but heat gain in summer should be minimal.
daytime the absence of openings desirable, especially on the west side; or the openings should be as small as possible and be shielded from direct radiation and located high on the walls to protect from ground radiation
night, the openings should be large enough to provide adequate ventilation for the dissipation of heat emitted by the walls and the roof. Hence larger openings should be closed during the day with insulated shutters and opened at night.
Such systems are not always reliable because they require the attendance and readiness of the inhabitants. Other considerations such as desired privacy and safety may prevent the correct use of a system with shutters.

27. Indirect natural light
Appropriate natural lighting is important.
The depth of rooms and the size of windows have to be coordinated.
Glare of direct natural lighting can also be avoided by the use of internally reflected light.
                                                                                                     Indirect natural light

28. Orientation and size of openings
Main openings should face north and south, but the latter should be shaded either by shading devices, roof overhangs or by deciduous trees. The size of the windows on the west and east sides should be minimized in order to reduce heat gains into the house in the early morning and late afternoon, or also be protected by particular shading devices. A moderate, south-facing glass area catches the solar radiation during the cold season, but should not be affected by direct radiation during the summer.
Generally, single glazing is sufficient. Insulating and special heat-absorbing and heat-reflecting glass is basically only suitable for air-conditioned buildings. Generally, single glazing is sufficient. Tight closing joints and window profiles are important to prevent the penetration of hot air, sand, dust and insects.

29. Placement of openings
suitable positions relation to the prevailing (cool) breeze to allow a natural airflow through the building, to achieve air movement across the body for evaporative cooling and air changes for driving out excess heat.
An internal draft (cross-ventilation) can be channeled by louvres set in an upward position towards the ceiling or in a horizontal position towards the human body. Outlet openings should be located at a high level where hot air accumulates.
For comfort, ventilation openings should be at the level of the occupants. High openings vent the hot air collecting near the ceiling and are most useful for convective cooling.

30. In buildings in coastal areas, openings for cross-ventilation should be equipped with movable shutters. Because of the hot land wind which occurs at night, openings facing the inland direction should be closable.
Difficulty of adjusting venetian blinds in summer:
(a) the position for the optimal direction
of the air movement is undesirable with regard to sunshine;
(b) the optimal position for blocking sunlight is undesirable with
regard to the wind direction.

31. Wind-catchers
in many different sizes, directions and height in relation to specific breeze to produce effective convective cooling.
the intolerable hotness of desert regions is because of land reflection, which excessively makes some maters of hot & brand air in the lower thin layer of land for this reason they have improvised a high air vent with at most 8 wings, for their houses, which is called Badgir or wind- catcher.
Windcatcher is one of the other elements of hot & dry architecture which is used for cooling and ventilation of internal spaces.

32. Wind-catcher is as constant complex which acts both by sucking & pulling. The basis of action is that wind blowing is used to suck the cold air to the inside of building and the reaction of it is used for sending out the hot and pollutant air from inside the building.
Once the wind come in contact with walls of internal wings of wind-catcher inevitably it descends and enters the building space, on the other hand the holes or vents of wind-catcher on the opposite side of wind blowing to the sucking and give the hot &pollutant air of building to the wind.

34. Wooden screens
In form of composite shading devices were used in the regions where wood was available: To control and filter daylight, and to reduce indoor glare.

36. Walls Block and heavy construction materials were used
Being considered as an important element in regional house of hot & dry climate, the huge walls have approximately thickness of about one meter.
These walls lose the heat through transferring and radiation during night and its temperature remains in low and average degree during the day, thus, it provides enough comfort for residents.
During the hot season, walls of daytime living areas should be made of heat-storing materials; walls of rooms for nighttime use should have a light heat capacity. East and west walls should preferably be shaded. High reflective qualities are desirable for both thermal and solar radiation

37. In regions with a less extreme diurnal temperature range and where the night temperature does not fall below comfort zone, the internal walls and intermediate floors should have large thermal masses, whilst the outer walls and roof need a high resistive insulation and reflectivity Double walls with insulation in between are a suitable solution.
In regions with large diurnal temperature ranges and night temperatures below comfort level, inner and outer walls and - especially in the absence of a ceiling - roofs should possess a large thermal capacity with an appropriate time lag to balance temperature variations. To achieve this they must be constructed of heavy materials. The use of exterior or interior insulation has to be considered carefully and its suitability depends on the particular requirements and technical possibilities.

38. Planting Temperatures of differently-treated surfaces
In desert regions the rate of planting depends on water amount and way of accessing to it. In hot & dry region the herbal space lots of effects on the small surrounding regions for the following reasons:
1. Decrease of direct radiation of sunbeams andyard space.
2. Shading on ceiling, walls, windows, and yardspace.
3. Decrease of dust in the surrounding environment
of building.
4. Decrease of undesirable wind speed in building surroundings.
5. Concentration of wind blow and increase of its speed in a desired direction.
6. Increase of humidity in dry regions.
7. Decrease of temperature in building surroundings.
In most of the houses of hot-arid regions of Iran, wind catcher has a direct connection to parch and this space is used for diversity of functions from morning to noon and inhabitants use the underground in the afternoon and roofs at night, which have colder weather, for sleeping.
                                                                                                                            Temperatures of differently-treated surfaces

39. Thank you and wasalam