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close this book National design handbook prototype on passive solar heating and natural cooling of buildings
View the document Foreword
Open this folder and view contents Introduction
Open this folder and view contents I. Principles of passive solar architecture
Open this folder and view contents II. The Australian climates and people
Open this folder and view contents III. Fundamentals of heat flow
Open this folder and view contents IV. Thermal comfort
Open this folder and view contents V. Basic design principles and strategies
Open this folder and view contents VI. Bio-climatic analysis and comfort strategies
Open this folder and view contents VII. Detail design
Open this folder and view contents VIII. Final design evaluation
View the document Annex I: Relevant Australian standards
View the document Annex II: Glossary of terms
View the document Annex III: Metric units of measurements
View the document Annex IV: Typical internal heat loads for appliances
View the document Annex V: Minimum additional thermal resistance requirements
View the document Annex VI: Climate data for Sydney region - mean daily insolation for Sydney
View the document Annex VII: Selected thermal properties of various building material
View the document Annex VIII: Selected u-values and r-values
View the document Annex IX: Heating degree day data - new south Wales
View the document Annex X: Glass-mass performance graphs
View the document Annex XI: Appraisal graphs for the 5-star design rating system
View the document Annex XII: Sun position charts for Australian capital cities
View the document Annex XIII: Bibliography and suggested reading

Annex III: Metric units of measurements

When studying thermal design of buildings, thermal comfort, solar energy and other related areas a number of units of measurement will be repeatedly encountered. Some will be familiar whilst others may not. To help clarify these the following information is provided.

Preferred multiples and submultiples

Prefix

Symbol

Factor

Magnitude

tera

T

1012

1000000000000

giga

G

109

1000 000 000

mega

M

106

1000 000

kilo

k

103

1000

milli

m

10-3

0.001

micro

µ

10-6

0.000.001

nano

n

10-9

0.000000001

pico

p

10-12

0.000000001

Reference: Metric Handbook (SAA-MHI)

Temperature is measured in degrees Celsius (°C); this unit replaces degrees Farenheit (°F) the conversion being:




In scientific work one may often encounter the Kelvin scale (°K). This scale has the same interval as °C but the starting point, known as absolute zero is equal to -273.15°C. i.e. 0°C = 273.15°K and a temperature difference of 5 deg C is the same as a temperature difference of 5 deg.K.

Note: The temperature of an object is written "°C" whilst the difference in temperature of two objects is written "deg.C".

The following are commonly used terms:

T = temperature difference (delta T)

Ta= ambient temperature (usually the air temperature surrounding the object concerned).

T = outside air temperature (usually dry-bulb temperature)

Ti = inside air temperature

Tei = environmental temperature

Work, heat and energy are measured in units called Joules (j)

1 joule = 1 watt for 1 second = rate of energy flow x time = a quantity

The unit of heat flow, energy flow or power Is the watt (W) as shown above.

Generally quantities of energy or heat in relation to buildings will be given in Mj, Gj or kWh. Heat or energy flow rates will be W or kW.

1 kWh=3.6MJ

(1000W x 3600 sec = 3 600 000 J = 3.6 MJ)

Many large single bar electric radiators give out heat at a rate of 1000W. Such a radiator would therefore consume 1 kWh of energy in one hour.

It is preferable to refer to quantities of heat or energy in Joules rather than watt-hours to avoid confusion with the watt.

Density of heat flow rate

If the total rate of heat flow from an identifiable unit is to be measured (such as heat loss from a given building or the radiation received from the sun) the unit of measurement is the watt (W or kW). The density of that flow rate (or intensity) is measured per unit area. Therefore the density or intensity of heat flow or solar radiation is measured in W/m².