Energy resourcesFossil fuels

Coal

Oil

Gas

Nuclear energy

Petroleum39%

Gas24%

Coal22%

Nuclear7%

Image by MIT OCW.

Energy resources

Renewable energiesWind

Coal22%

Nuclear7%

Renewables8%

Petroleum39%

Gas24%

Image by MIT OCW.

Energy resources

Renewable energiesWind

Solar thermal

Coal22%

Nuclear7%

Renewables8%

Petroleum39%

Gas24%

LATITUDE

LATITUD

E

LATITUDE + 15o-15o

1 2 3

Image by MIT OCW.

Image by MIT OCW.

Energy resources

Renewable energiesWind

Solar thermal

Photovoltaic

Coal22%

Nuclear7%

Renewables8%

Petroleum39%

Gas24%

Image by MIT OCW.

Energy resources

Renewable energies storage issueWind

Solar thermal

Photovoltaic

Hydroelectric (& Tidal)

Coal22%

Nuclear7%

Renewables8%

Petroleum39%

Gas24%

Image by MIT OCW.

Energy resources

Energy conversion ElectricityElectric heating only half as efficient as direct fuel combustion

Coolwater in

Warmwater out

Waterway

CondensatePump

Fuel

Generator

SteamTurbineBoiler

Electrical Energy

Condensor

Conversion Device Efficiency, η

0.300.60

0.700.700.75

0.05-0.200.18-0.40

0.20-0.28

0.32-0.38

0.30-0.35

0.970.92

0.98

0.75

0.99

Open fireplaceCoal fired boiler, manual feed

Coal fired boiler, automaticOil fired boilerGas fired boiler

Steam piston enginesSteam turbines

Petrol engines

Diesel engines

Gas turbines

AC generatorAC motor

TransformerLead-acid battery

(input-output)

Electric heating

Chemical-to-heat

Heat-to-mechanical

Chemical-to-mechanical

Electrical

Image by MIT OCW.Image by MIT OCW.

Active controls: HVAC

Two parameters to be knowncapacity­ depends on building’s heat losses

­ depends on ΔT between comfort °T and worst outside °T

heating requirements­ depends on time of the year

Active controls: HVAC

Local heatingOil heater

Stove (solid fuel)

Gas heater

Electric heaterInfrared lamps

Incandescent radiators

Medium temperature (tube or panel) radiators

Low temperature panels (oil filled)

Convectors

Fan-convectors

Storage (block) heaters

Floor warming

Ceiling warming

TypeHeat emission (%)

Radiant Convective

100

100

80

80

80

60

6040

40

20

20

10

20

3070

90

Image by MIT OCW.

Active controls: HVACLocal heating

Oil heater

Stove (solid fuel)

Gas heater

Electric heater­ Heat pump

20

15

10

5

0-10 10 20 300

(Cold) Source temperature (oC)

(Warm) Sink (room) temperature (oC) 20304050

CO

P

CompressorHigh pressure

vapour

High pressure liquid Low pressure liquid

Low pressurevapour

Sink Source

Con

dens

er

Evap

orat

or

Choke (Pressure release valve)

Image by MIT OCW.

Image by MIT OCW.

Active controls: HVAC

Central heatingAir based

Water based

Ret

urn

duct

Supplyducts

Burneroiltank

FanDust filter

Oil Tank

0,33 0,33 for

Control valveConvector

Air vent

Returnfitting Pump

Comtank

Boiler

h/m 3Kh/m 3K

pression

1161 kWh/m3K

kW

Air duct for

Water

1161 kWh/m3K

kW

Air duct

pipe

for

Images by MIT OCW.

Active controls: HVACVentilation and air-conditioning

Mechanical ventilation

Air-conditioning­ Conventional room conditioner­ Open-cycle cooling

Radiating surfaces

Outdoor air

Room air

CD

C M E

Sump with float valve for make-up water

Fibrous material pade.g. wood shavingsin cheese cloth

Perforated drip pipe

Pump MotorFan

Images by MIT OCW.

Active controls: HVAC

Integration and occupants’ comfortFloor warming slow but comfortable

Convectors quick but not for massive/badly insulated spaces

Local radiative heating towards people for large spaces

Passive and active heating combinationHeating system coherent with solar gains

stops when gains overcome needs

requires temperature or solar radiation sensor (separation N/S)

NS

SAF

AF

VMVM

VF

AF

VF

VM

Image by MIT OCW.

Passive and active heating combinationHeating system coherent with solar gains

stops when gains overcome needs

requires temperature or solar radiation sensor (separation N/S)

requires low inertia of heating system

[h]

Air

[h]

Radiator

[h]

Floor

0 2 4 6 8 10 12 14 16 0 2 4 6 8 10 12 14 16

0 2 4 6 8 10 12 14 16

Image by MIT OCW.

Passive and active heating combination

Heating system coherent with solar gainsstops when gains overcome needs

requires temperature or solar radiation sensor (separation N/S)

requires low inertia of heating system

autoregulation difficult with high temperature heating systems

Active Heating and Cooling

Reading assignment from Textbook:“Introduction to Architectural Science” by Szokolay: § 1.6 + § 4.1 - 4.2

Additional readings relevant to lecture topics:"How Buildings Work" by Allen: pp. 77 - 88 in Chap 10 + Chap 15

"Heating Cooling Lighting" by Lechner: Chaps 2 + 8 + 16

“The Technology of Ecological Building“ by Daniels: Chaps 10 – 12

More detailed information about renewable energy"Sustainability at the cutting edge – Emerging technologies for low energy buildings" by Smith