Introduction to passive design
The definition of passive design is the design of a building taking into consideration all aspects of the climate and the environment to either heat up or cool down the occupants (to achieve thermal comfort)through natural means and not artificially to conserve energy used. The purpose of passive design is to minimize the energy consumption and to improve the thermal comfort. There are several principles that we should consider in order to produce a passive building design such as the orientation, materials, insulation, thermal mass, ventilation, and shading. To implement the passive design approach we should first understand the criteria of thermal comfort, analyse the local climate, and establish measurable energy performance targets.
What are the principles of passive design and how to apply it?
1) Location, orientation and layout
The location and orientation of the house can affect the ability to receive solar radiation and to encourage the interior air movement. In order to receive optimum solar radiation and sufficient interior air movement, the floor plan of a house for hot and humid climate usually provide spread-out floor plans and permeable internal organization.
2) Material and colour
In hot and humid climate, materials for building envelope and surrounding surfaces should help minimise heat gains into the building or a house. Survey shows that many traditional houses in hot and humid climates use lightweight materials such as wooden walls and woven bamboo flooring. It different with current situation in which modern materials is used such as plasterboard, and lightweight concrete blocks.
Insulation is a product that blocks the transfer of heat. It acts as a barrier to heat flow and help in keeping the house maintain comfortable for the interior spaces. Heat flows naturally from warmer to cooler space. Other than that, it also help to control any form of sound transmission. Usually insulation is needed in the ceiling, walls, and floor. The most appropriate time to install the insulation is during the construction.
4) Thermal mass
Thermal mass can be defined as a material that have the capacity to store thermal energy for an extended periods. Usually the properties of thermal mass materials are high in density, good thermal conductivity and low reflectivity. Materials used are usually concrete bricks, sandstones, water, and stones.
The ventilation should be designed to achieved sufficient air flow rates. The higher the temperature and the humidity,the more air is needed to achieve thermal comfort. When designing a natural ventilation system, the long facade of the building should be facing the prevailing wind direction, with doors and opening windows providing the ventilation openings. Adequate ventilation may ensure that the indoor temperature does not become higher than the outdoor.
The purpose of shading is to control intense direct sunlight to ensure a comfortable for the interior space and at the same time minimizing the mechanical cooling loads. Shading should be designed to take into account the sun's path during the day.
Why passive design is important in Islam?
1) “La darar wala dirar fil Islam”.
This Hadeeth is present in the 40 Ahadeeth of Imam Nawawi (RA), Hadeeth number 32 : On the authority of Saad bin Malik Al-Khudar (RA), that the messenger of Allah (Rasulullah saw) said : "There should be neither harming nor reciprocating harm." (Related by Ibn Majah, Al-Daraqutni and others) .
From this hadeeth, it shows that in Islam we are not allowed to create something that can harm the our surrounding. In other words, passive design is important to make sure that the built environment process does not harm the natural surroundings.
2) Surah al-Ahzab verse 72
“Indeed, we offered the Trust to the heavens and the earth and the mountains, and they declined to bear it and feared it; but man [undertook to] bear it. Indeed, he was unjust and ignorant.”
From this quranic verse it proves that Allah has offered human being ‘amanah’ to be a khalifah on earth. So that, it is human being responsibility of putting into application the divine laws on earth in order to keep the earth well balanced.
3) Surah Ibrahim verse 33-34
“And He subjected for you the sun and the moon, continuous [in orbit], and subjected for you the night and the day. And He gave you from all you asked of Him. And if you should count the favour of Allah , you could not enumerate them. Indeed, mankind is [generally] most unjust and ungrateful.”
It shows that, it is important to being grateful for the present of the earth means to take care of it, that is to use it in a sustainable manners.
4) Surah al-Rum verse 41
“Mischief has appeared on land and sea because of (the need) that the hand of men have earned, that (Allah) may give them a taste of some of their deeds: in order that may turn back (from evil).”
All things have been created in a due proportion and measure (carefully balanced). Once the balance is disturbed, we should expect the worst, such as global warming and other kind of environmental destructions.