Climate and Comfort: Bioclimatic Chart Comfort: energy budget

Comfort: energy budget
Università IUAV di Venezia, Environmental Building Physics– Introduction to sustainability
Integrated Studio 1 – Master Degree in Architecture and Innovation
∑Q
Climate and Comfort:
Bioclimatic Chart
Fabio Peron
Università IUAV - Venezia
Comfort
= Q
K
+ Q
C
+ Q
R
Qcond - conduction between body and
envelope surfaces;
Qconv - convection between body and air;
QR
- radiation between body and
envelope surfaces;;
– sensible heat associated with
Qsi
breathing;
QLi
- latent heat associated with
breathing;
ED
- sensible heat associated with
transpiration;
- latent heat associated with
ES
transpiration
.
Comfort
•
•
•
•
•
•
Clothing, Icl
Activity, Met
Air temerature, ta
Air velocity, va
Air humidity, URa
Mean radiant temperature, tmr
There is not a single condition of comfort , but the comfort conditions
are defined by the endless combinations of the six variables
The feeling is subjective and the same environmental conditions on
differnt persons can lead to different sensations.
+ Q
Fanger DTU Lyngby (DK)
PMV = f (Icl, M, ta, va,URa, tmr)
PPD = g (PMV)
Sr
+ Q
Lr
+ Q
Ed
+ Q
Es
Adaptation
Proportion of subjects comfortable
Adaptation
Comfort is achieved
by the occupants
adapting to the
building
Occupant
Building
Or by the occupants
adapting the building
to suit them
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Little discomfort
12 14 16 18 20 22 24 26 28 30 32 34 36 38
Mean indoor temperature oC
All this in a specific social, economic and cultural context
Comfort level with various indoor temperature. Investigation in offices in Pakistan
Nicol, Raja, Allauddin & Jamy (1999) Energy and Buildings 30
Adaptation
Adaptation
35
Neutral or comfort temperature oC
Comfort temperature
AC buildings, line B
30
25
20
34
Free-running buildings, line A
32
30
28
A
26
B
24
22
20
18
16
Tn = To
14
12
15
-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0
10
15
20
25
30
35
40
2
4
6
8 10 12 14 16 18 20 22 24 26 28 30 32 34
o
Monthly mean outdoor temperature C
Mean temperature experienced
Comfort and mean external temperature in Pakistan
Nicol, Raja, Allauddin & Jamy (1999) Energy and Buildings 30
Humphrey in1978 from field studies. Each point represents a research campaign.
In free-running building expectations are less stringent.
Adaptation
50 F
59 F
68 F
77 F
86 F
95 F
86.0
24
22
BANGKOK
PALERMO
TOKYO
PERTH
TORINO
STOCKOLM
AMSTERDAM
26
FRANKFURT
28
NEW DELHI
30
o
indoor operative temperature ( C )
32
SINGAPORE
Adaptation
82.4
78.8
75.2
71.6
90% acceptability limits
20
68.0
18
80% acceptability limits
64.4
16
60.8
14
5
10
15
20
25
30
35
o
mean monthly outdoor air temperature ( C)
ASRAE 55-2004
Adaptive comfort and Fanger model
Climate and comfort: Olgyay chart
This famous
illustration is taken
from “Design with
Climate”, by Victor
Olgyay, published in
1963.
This is the finite
point of expected
comfort for
100% mechanical
heating and
cooling.
Green area is the
comfort area: we
can use different
conditions
Climate and comfort: Olgyay chart
Climate and comfort: Olgyay chart
You can actually identify
two areas of comfort, a
summer and a winter one
(upper and lower), relating
to an scantily dressed (Clo =
0.8), in sedentary activity
(Met 1) and in the shade (no
solar radiation) .
The part below the comfort
zone describes conditions
undercooling, the above
overheating.
Olgyay Chart
Olgyay Chart
Punto B
Temperatura a bulbo secco
aria: 75 °F ≅ 23,9 °C
Point A
Air temperature:
75 °F ≅ 23,9 °C
Air Relative Humidity: 50%
A
condition:
Summer COMFORT
Winter COMFORT (limit)
No intervention:
It falls into the comfort zone
Umidità relativa: 70%
B
condizione: non COMFORT
accorgimento necessario:
Moto aria: 120 fpm ≅0,61 m/s
Olgyay Chart
Olgyay Chart
Punto D
Temperatura a bulbo secco
aria: 87 °F ≅ 30,6 °C
Punto C
Temperatura a bulbo secco
aria: 50 °F ≅ 10 °C
Umidità relativa: 56%
D
condizione: non COMFORT
condizione: non COMFORT
C
oppure
vapore d’acqua:
8 grains/pound ≅ 1,14 g/kgas
Olgyay Chart
Punto E
Temperatura a bulbo secco
aria: 95 °F ≅ 35 °C
E
accorgimenti necessari:
vento: 300 fpm ≅ 1,52 m/s
accorgimento necessario:
radiazione: 250 Btu/(h ft2)
≅ 788 W/m2
Olgyay Chart
Umidità relativa: 30%
Umidità relativa: 20%
condizione: non COMFORT
accorgimenti necessari:
vento: 700 fpm ≅ 1,52 m/s
in più vapore d’acqua:
8 grains/pound ≅ 1,14 g/kgas
Oppure vapore d’acqua:
22 grains/pound ≅ 3,14 g/kgas
Some modifications to the
original Olgyay chart:
Substitution of sun
radiation (typical of
external environment)
with mean radiant
temperature Tmr (typical
of internal environment).
Added different clothing
resistence levels
reaching comfort
Olgyay Chart
Climate and comfort: Olgyay chart
In the diagram, you can
report the climatic
conditions of the site
considered, highlighting
the " climate criticities" in
relation to the comfort .
In the chart some others
lines related to specific
conditions:
•
•
•
•
•
•
•
•
•
colpo di sole
colpo di calore
congelamento delle dita
limite di congelamento
limite di sopravvivenza
limite per certe attività
limiti per vestiario
condizioni di troppo secco
condizioni di troppo
umido
Olgyay chart: considerations
The Olgyay Bioclimatic Chart is usefull for buildings design when air
temperature inside the building is next to the outside: it happens in the
summer at mid and low latitudes for humid climates , and is especially true
as more buildings are light and naturally ventilated by opening doors and
Venice climate is humid
with cold winter.
Warm periods with high
humidity (scirocco wind,
summer sultriness).
Givoni chart
To get around the problem that can arise from the direct use of external climatic data in
the chart, Baruc Givoni in 1969 proposed a new bioclimatic chart “Building Bio-Climatic
Chart” based on ASHRAE humid air diagram and integrating the building factor..
windows .
In Olgyay chart it does not consider the presence of the building
The plot is not very effective for massive buildings in hot, dry climates:
here the indoor air temperature is always very different from the outside,
without any HVAC System.
CE
In these cases the signs of Olgyay lead to overestimation of the
interventions to ensure comfortable conditions .
CI
Givoni chart
Givoni chart
Givoni vs Olgyay Charts
Brown Chart
Differenze del diagramma di Givoni rispetto a quello di Olgyay:
•
•
Si considera la presenza dell’edificio
La zona di comfort invernale è molto più vasta di quella estiva (si presuppone
vestiario più pesante e attività più intensa )
•
Si riportano zone in cui le condizioni di temperatura e umidità esterna possono
garantire il comfort interno utilizzando sistemi passivi (senza il ricorso
all’impianto). Si considerano quattro principali sistemi:
a) ventilazione diurna
b) elevata massa (inerzia termica)
c) ventilazione notturna (anche in aggiunta alla massa elevata)
d) raffrescamento evaporativo diretto
e) raffrescamento evaporativo indiretto
•
I confini delle zona di comfort nel BBCC sono determinati dalle temperature
interne previste nell’edificio senza impianto e bioclimaticamente progettato.
Brown, De Kay 2001
Brown Chart
Brown Chart
Madison (Wisconsin):
Natural ventilation can be sufficient for cooling needs
Sun radiation isn’t sufficient for the heating needs (very cold climate).
Brown, De Kay 2001
Brown, De Kay 2001
Climatic needs
Brown Chart
Charleston (South Carolina):
Natural ventilation can be sufficient for cooling needs
Sun radiation can be sufficient for the heating needs
Brown, De Kay 2001
Climatic needs
Bioclimatic Chart and design evaluations
Bioclimatic Chart and design evaluations