Climate and Architecture Dr. Abdelrahman Elbakheit References العناصر المناخية و التصميم المعمارى, د. سعيد عبد الرحيم سعيد بن عوف .1 2. العمارة و المناخ , د. هاشم عبود الموسوى 3. Climate considerations in buildings and urban Design. Baruch Givoni

Thermal Characteristics for Building materials: -Thermal performance of building materials differs according to its thermal physical properties. -Studying and analyzing these thermal properties is important to: Selection of the right materials for the right utilization. To know how it respond to climate elements. -Therefore it is important for an Architect to know to the reaction of building materials for the climate. - One of the main reactions of the materials to the climate are principles of heat transfer for building materials. Heat transfers from hot areas to cold areas. Main processes of heat transfer : Thermal Conduction. Thermal Radiation. Thermal convection.

How to measure heat flow ? 1.Rate of heat flow: Is mount of heat passing through a unit area or volume in a unit time. Generally measured in Joule/ second = Watt 2.Heat Flux intensity: Is the amount of heat passing through an unit area or volume. Generally measured as Watts/m2. Thermal conduction: Is the heat transfer through the external building materials. How it is done? - Through moving molecules of building materials. More heat = more motion of building materials. For e.g. in roofs of concrete the outside of the slab gets heated first, this heat is manifested in more motion to molecules on that part. This motion affects nearby molecules so their motion is increased as well. By this heat transfer from on side to the other.

Heat transfer rate in one material depends on: Temperature difference between both sides of the material. Thermal conductivity of the material. Heat capacity of the material. Thermal conductivity: Is the amount of heat transferring through a unit area in a unit time. Or Is the rate of heat transfer in a unit area, with one unit temperature difference between the sides of the of a material having a unit thickness. Thermal Conductivity depends on: Density/ porosity. Moisture content. (linear) Absolute temperature of the material. Thermal Resistance: Is a measure to the resistance of one material or group of materials to heat transfer by conduction.

Thermal Resistance: Is a measure to the resistance of one material or group of materials to heat transfer by conduction. It can be regarded as the time taken to transfer I unit of heat through I unit of area in a material with I unit of thickness OR It can be regarded as temperature difference between two surfaces having - I unit of Thickness transferring - I unit of heat in. I unit of time. Thermal resistance is proportional to material thickness Thermal Conductance: Is the rate of heat transfer through a material or groups of materials connected together. Or it is the amount of heat transferred from one side of a material to the other with - I unit Thickness. - I unit temperature difference. _ I unit time and - I unit area.

-What happens in conducing heat transfer through a wall construction? Units of thermal conductivity : In imperial units it is : British Thermal unit (BTU)/ h. foot square - Degree fahranheight. (K) = Conductivity , 1/K = (R) Resistively. In international units: Kilo Calorie's. meter square – degree centigrade. (λ) =conductivity, 1/λ = (R) Resistively.

R = d1/λ1 + d2/λ2 + d3/λ3 …….+ dn/λn The U- Value: -Is the rate of heat transfer from the free outside air to the inside air and vice versa. -So we can compare different constructions ability to stop heat transfer by conduction by its U-value. -The only difference between thermal conductivity and the U-value is that the U-value contains the total resistance form each construction layer and both the inside and outside air layers. U= 1/R R = d1/λ1 + d2/λ2 + d3/λ3 …….+ dn/λn U=1/ 1/h +1/h0 + d1/λ1 + d2/λ2 + d3/λ3 …….+ dn/λn U= WATT/m2 -degree Celsius