HEAT

Definition of Heat?

Definition

• Heat is the amount of energy (thermal energy) that every body or object is radiating, resulting in molecule movement due to temperature gradients. The term heat in general can be defined as the movement of energy from one system to the environment deriving as a sole consequence of the temperature difference between them.

Units of Measurement • Calorie (cal) and Kilo-calorie (kcal) was the unit of

measurement that was initially applied for heat measurement. One Kcal is defined as the amount of energy that a liter of water requires in order to increase its temperature by one degree Celcius under normal conditions of pressure.

• Unit of Measurement in SI is joule. BTU is used in cooling (air conditioning)kcal is used in heating (Burner)

• 1 BTU = 1.055 Joule 1.000 Joule = 0,947 BTU• 1 kWh = 3.600.000 Joule 10.000.000 Joule = 2,777 kWh• 1 kcal = 4.186,8 Joule 10.000 Joule = 2,388 kcal• 1.000 BTU = 0,293 kWh 1 kWh = 3.412 BTU• 1.000 kcal = 1,163 kWh 1 kWh = 859 kcal

HEAT TRANSFER1. CONDUCTION OR DIFFUSION

The transfer of energy between objects that are in physical contact so that an equilibrium is achieved (e.g. when body temperature is measured).

2. CONVECTIONThe transfer of energy between an object and its environment, due to fluid motion.

3. RADIATIONThe transfer of energy to or from a body by emission or absorption of electromagnetic radiation. Heat is transferred by radiation either through matter or through vacuum of space. The most prominent example of heat radiation is the heat transfer from the Sun to Earth. Thermal radiation is a direct result of the random movements of atoms and molecules in matter. Since these atoms and molecules are composed of charged particles (protons and electrons), their movement results in the emission of electromagnetic radiation, which carries energy away from the surface. Thermal radiation emission is achieved due to electromagnetic waves,

ΚΕΝΑΚ IS A TOOL ADDRESSING:1. THE WAY NEW BUILDINGS SHOULD BE BUILD 2. THE CERTIFICATION OF EXISTING BUILDINGS FOR

THEIR ENERGY EFFICIENCY LEVEL

BUILDING ENERGY EFFICIECNY LEGISLATION (Κ.ΕΝ.Α.Κ)

LAW 3661/2008

FOUNDING EQUATION IN HEAT TRANSFER

Q = A * U * ΔΤ

Q: Heat Flow (kWh/h)A: Surface (m2)ΔΤ: Temperature Gradient (Κ)U: Heat Conductance Co-efficient (W/m2K)

Heat Circulation Summer Winter

Climatic Zones in GreeceClimatic Zones in Greece

Building Categories Building Use

Housing House, Block of apartments (building of more than one independed apartments) ,

Temporary Housing Hotels, Hostel, Boarding, Dormitory.

Public Gathering place Convection center, exhibition center, museum, concert hall, theater, cinema, court, fitness center (closed), closed swimming pool, restaurant, patisserie, coffee shop, bank, multiplexes..

Education Kindergarten, Elementary School, High School and Senior High School, Higher Education, teaching rooms etc

Health and Social Welfare Hospital, Clinic, Rural surgery, Surgery, Health Center, Doctor’s Office, Psychiatric Clinic, Special Needs Therapy Center, nursery, etc.

Reformation Centers Prison, rehabilitation center

Commerce Shop, Commercial Center (shopping mall) , hypermarket, chemist shop, hairdresser’s shop etc.

Office Office, Library

Storage Storing warehouse, shop storage, museum storage.

ESSENTIAL POINTS DURING THE ENERGY CERTIFICATION PROCESS

1. BUILDING ENVELOPE External Building Surface, Openings, Floors, Ceilings, Orientation, Shading, Ventilation

2. REFERENCE BUILDING3. HEATING SYSTEM (Boiler), COOLING SYSTEM (Air Conditioning),

HOT WATER SYSTEM (Solar or Electric)

Building Envelope in the 4 Climatic Zones in GreeceBuilding Envelope in the 4 Climatic Zones in Greece

Energy Efficiency in various Building Categories

Category Category Limit Category Limit

Α+ ΕΡ ≤ 0,33RR T ≤ 0,33

Α 0,33RR < ΕΡ ≤ 0,50RR 0,33 < T ≤ 0,50

Β+ 0,50RR < ΕΡ ≤ 0,75RR 0,50 < T ≤ 0,75

Β 0,75RR < ΕΡ ≤1,00RR 0,75 < T ≤ 1,00

Γ 1,00RR < ΕΡ ≤ 1,41RR 1,00 < T ≤ 1,41

Δ 1,41RR < ΕΡ ≤ 1,82RR 1,41 < T ≤ 1,82

Ε 1,82RR < ΕΡ ≤ 2,27RR 1,82 < T ≤ 2,27

Ζ 2,27RR < ΕΡ ≤ 2,73RR 2,27 < T ≤ 2,73

Η 2,73RR < ΕΡ 2,73 < T

EXAMPLE OF A HOME ENERGY CERTIFICATE

EXERCISE FOR GROUPS A,B,C

  HEAT (Wh/h)

EXTERNAL SURFACE GROUP Α GROUP Β GROUP C

EASTERN 1.392,12 428,90 765,00

SOUTH 1.597,32 423,14 739,80

WEST 1.451,52 480,38 864,00

NORTHERN 1.441,80 288,36 480,60

FLOOR 1.986,48 768,96 1.986,48

CEILING 4.613,76 576,72 1.153,44

TOTAL 12.483,00 2.966,47 5.989,32

RESULT COMPARISON

RATIO OF CONSUMPTION /

REFERENCE BUILDING

GROUP Β 2.966,47 Wh/h 2.966,47/2.966,47 1,00

GROUP Α 12.483,00 Wh/h 12.483,00/2.966,47 4,21

GROUP C 5.989,32 Wh/h 5.989,32/2.966,47 2,02

GROUP’S Β BUILDING BELONGS TO

Β ENERGY CLASSIFICATION SCALE

GROUP’S Α BUILDING BELONGS TO

Η ENERGY CLASSIFICATION SCALE

GROUP’S C BUILDING BELONGS TO

Ε ENERGY CLASSIFICATION SCALE

E-SOURCES FOR LITERAURE REVIEW

• http://el.wikipedia.org