Passive controls
Passive solar heating
ƒ Direct gain and control of heat flow
­ control of sunlight penetration
­ good thermal quality of window (thermal insulation, thermal bridges)
­ proper orientation
­ other factors
Low-E
placement for
warm climates
Low-E
placement for
cold climates
Passive controls
Passive solar heating
ƒ Direct gain and control of heat flow
ƒ Heat storage wall (transparent insulation)
­ stores heat in wall mass
­ adds to direct gain
Image by MIT OCW.
Passive controls
Passive solar heating
ƒ Direct gain and control of heat flow
ƒ Heat storage wall
­ stores heat in wall mass
­ adds to direct gain
SUMMER
WINTER
MASONARY
BLACK
GLASS
Trombe wall
Image by MIT OCW.
Passive controls
Passive solar heating
ƒ Direct gain and control of heat flow
Winter
ƒ Heat storage wall
ƒ Greenhouse
­ heat collection during the day
­ buffer during the night
Summer
Image by MIT OCW.
Passive controls
Passive solar heating
ƒ Direct gain and control of heat flow
ƒ Heat storage wall
ƒ Greenhouse
­ heat collection during the day
­ buffer during the night
­ design constraints
­ draw-backs
Passive controls
Passive solar heating
ƒ Control Potential Zone
­ limit temperature(s) achievable with passive control:
Dv x A x η = q x (Ti – To)
30
%
40
%
­ report on psychrometric chart and determine CPZ
15
2
ET 40
0%
·
SET
Image by MIT OCW.
0
SET 3
20
5
·
ET 25
ET 20
·
·
30
22.3 24.8 27.3°C
40
10
8.5
g/kg
35
·
%
10
11.5
50
0
Passive controls
Passive solar heating
Thermal mass
Passive controls
Jacobs House II in Wisconsin (Frank Lloyd Wright)
Photographs and floor plans removed due to
copyright restrictions.
Passive controls
Theuer House in Phoenix AZ (William Bruder)
Photograph and floor plan removed due to copyright
restrictions.
Passive controls
Passive solar heating
Thermal mass
ƒ mass distribution
ƒ continuous occupation
ƒ cold or hot-dry climates
35
ƒ night ventilation
Temperature (oC)
ƒ specific mass
Day Ventilation
30
25
Night Ventilation
20
15
Image by MIT OCW.
2
3
4
5
Date in August
6
7
Outside oT
Passive controls
Passive solar heating
Thermal mass
Boundaries of the Control Potential Zone
30
Solid: with 1 m/s velocity
Dotted: with 1.5 m/s
25
20
15
Air movement
10
ƒ heat dissipation
ƒ cross-ventilation or fans
ƒ apparent cooling effect:
5
-10oC
0
Image by MIT OCW.
10
20
Cross-ventilation
Two openings
dT = 6v - 1.6v2
Stationary
warm air
One opening
30
40
50
0g/kg
Chimney
Passive controls
Passive solar heating
Thermal mass
Air movement
Fibrous material pad
e.g. wood shavings
in cheese cloth
Evaporative cooling
Perforated drip pipe
Pump
Motor
Fan
Image by MIT OCW.
Sump with float valve for make-up water
Thermal balance
Equilibrium of heat gains and losses
Qi + Qc + Qs + Qv + Qe = 0
Thermal balance
Qi + Qc + Qs + Qv + Qe = 0
ƒ Qi = internal gain (±)
Internal Gains
Heat Balance: QF + QV + QS + QI + QE
Image by MIT OCW.
Thermal balance
Qi + Qc + Qs + Qv + Qe = 0
ƒ Qi = internal gain (±)
ƒ Qc = conduction gain (±)
Summer Sun
Approx.
Outside Air
O
Temp 30
Fabric Gains
Heat Balance: QF + QV + QS + QI + QE
Image by MIT OCW.
Thermal balance
Qi + Qc + Qs + Qv + Qe = 0
ƒ Qi = internal gain (±)
ƒ Qc = conduction gain (±)
Winter Sun
ƒ Qs = solar gain (+)
Approx.
Outside Air
O
Temp 12
Solar Gains
Heat Balance: QF + QV + QS + QI + QE
Image by MIT OCW.
Thermal balance
Qi + Qc + Qs + Qv + Qe = 0
ƒ Qi = internal gain (±)
ƒ Qc = conduction gain (±)
ƒ Qs = solar gain (+)
ƒ Qv = ventilation gain (±)
Ventilation Gains
Heat Balance: QF + QV + QS + QI + QE
Image by MIT OCW.
Thermal balance
Qi + Qc + Qs + Qv + Qe = 0
ƒ Qi = internal gain (±)
ƒ Qc = conduction gain (±)
ƒ Qs = solar gain (+)
ƒ Qv = ventilation gain (±)
ƒ Qe = evaporative loss (-)
Evaporative Gains
Heat Balance: QF + QV + QS + QI + QE
Image by MIT OCW.
Thermal balance
Qi + Qc + Qs + Qv + Qe = 0 for design project
ƒ Qi = internal gain (+) = secondary heat sources + primary heating
ƒ Qc = conduction gain (-)
ƒ Qs = solar gain (+)
ƒ Qv = ventilation gain (-)
Passive gains/losses
(for early March)
ƒ Qe = evaporative loss (-) ≈ 0
determine active ("primary") heating component in Qi
Integrated approach: new classroom at MIT
Criteria and risks for
ƒ site
ƒ envelope
ƒ materials
ƒ …
Passive controls, Thermal Balance
Reading assignment from Textbook:
ƒ “Introduction to Architectural Science” by Szokolay: § 1.4 (Intro) +
§ 1.5.1 - 1.5.2
Additional readings relevant to lecture topics:
ƒ "How Buildings Work" by Allen: Chap 9 + pp. 73 - 77 in Chap 10
ƒ "Heating Cooling Lighting" by Lechner: Chaps 7 + 10