Architecture 418 Spring 2012 Designing with Natural Forces Peter ...

Architecture 418 Spring 2012
Designing with Natural Forces
Peter Simmonds
Course Title: Designing with Natural Forces 418
"Investigation of how natural forces can be harnessed to enhance Architecture and
Natural Ventilation of spaces to provide ventilation air and occupant comfort."
Course: ARCH 418
When: Thursdays 3pm-6pm
Where: Beckett Boardroom
Instructor: Peter Simmonds
Course Description:
Natural ventilation can be successfully used to condition and ventilate buildings and spaces and be
substantial component of many sustainable strategies. Natural Ventilation can also provide occupant
comfort. The phenomenon of natural ventilation is quite often misunderstood. It is not simply a way of
orientating the building in the correct direction or having openings in the façade that will facilitate air
movement through a space.
Both Buoyancy Driven and Wind Driven can be utilized to provide natural ventilation, but how are these
designed? This course will examine the physical factors in design through a series of lectures and design
Charrettes. In this process the students will learn the various ecological factors that can impact the
environment such as:
Topography and the site
Sun exposure
Wind dynamics
Aero Physics
Wind Driven Ventilation
Buoyancy Driven Ventilation
Stack Ventilation in High Rise Buildings
The course will be broken down into the following sections:
a. Introduction to terminologies and analytical tools through readings from reader
b. Introduction to available computer tools
c. Introduction to adaptive comfort for naturally ventilated spaces.
d. Analysis of wind driven ventilation
e. Analysis of buoyancy driven ventilation
f. Stack ventilation in High Rise Buildings
g. Discussions of practical applications
h. Midterm Exams (2x)
i. Homework
j. Final Exam
In
its
simplest
form,
natural
ventilation
is
as
simple
as
opening
a
window
or
door;
it
permits
some
form
of
air
exchange
with
the
outdoors.
At
the
other
end
of
the
spectrum,
natural
ventilation
implies
an
engineered
balance
of
driving
forces
and
pressure
losses
to
move
air
through
a
building
at
predictable
minimum
flow
rates,
to
provide
adequate
ventilation
for
air
quality,
for
thermal
comfort
and
to
manage
heat
loads.
Humans
have
a
long
history
with
natural
ventilation.
It
has
been
used
to
ventilate
all‐types
of
buildings
from
hospitals,
schools
and
homes,
to
electrical
sub‐stations
and
industrial
facilities.
Natural
ventilation
requires
the
management
of
the
two
principal
driving
forces:
the
buoyancy
force
associated
with
a
temperature
difference
and
the
kinetic
force
associated
with
wind
movement.
In
each
case,
pressure
differences
are
set
up
between
the
indoor
and
outdoor
environment,
which
drives
the
airflow.
The
restraint
on
natural
ventilation
is
associated
with
pressure
losses
as
air
moves
through
openings
(expansion
and
contraction
of
flow
area),
turns
corners
and
passes
through
screens
or
filters.
Some
buildings
are
difficult
to
ventilate
naturally
in
a
“managed”
way.
Very
tall
buildings
can
be
difficult
to
ventilate
naturally
because
the
combination
of
wind
and
stack
effect
pressures
can
lead
to
adverse
flow
directions
—
people
in
one
location
receiving
the
stale
air
from
those
in
another.
Wind
pressures
can
also
lead
to
uncomfortable
conditions.
It
is
possible
to
naturally
ventilate
super‐tall
buildings
but
this
feature
must
be
designed‐in
from
the
beginning.
Some
jurisdictions
(e.g.
Chicago)
Course Syllabus Page 1 of 3

Architecture 418 Spring 2012
Designing with Natural Forces
Peter Simmonds
require
that
all
residences
have
operable
windows,
even
though
in
some
cases,
these
windows
are
not
useful
to
the
occupant.
In
general,
natural
ventilation
works
best
when
the
outside
air
temperatures
are
just
below
what
would
generally
be
considered
comfortable
indoor
conditions.
However,
the
outdoor
temperature
that
will
lead
to
acceptable
indoor
temperatures
depends
greatly
on
the
internal
heat
loads
(from
human
occupants,
equipment,
lights,
solar
gain,
etc.)
and
the
flow
rate
that
can
be
achieved.
The
American
Society
of
Heating,
Ventilating
and
Air
Conditioning
Engineers
(ASHRAE)
Standard
55
(2010)
has
a
discussion
on
thermal
comfort
that
includes
a
chart
highlighting
the
acceptable
indoor
temperatures
in
naturally
ventilated
buildings.
The
key
is
that
occupants
must
be
given
some
measure
of
control
over
their
environment.
Design
of
natural
ventilation
in
a
complex
building,
or
where
natural
ventilation
is
the
only
form
of
ventilation,
can
involve
intuitive
experience
as
well
as
hard
science.
In
each
case,
the
form
of
the
building
will
be
important
and
various
features
of
the
building’s
architecture
can
enhance
natural
ventilation
or
work
against
it.
Designing
natural
ventilation
is
the
art
of
balancing
driving
forces
and
pressure
losses
to
achieve
a
desired
minimum
air
flow
rate.
The
required
minimum
flow
rate
need
not
be
constant.
In
general
there
are
three
different
criteria
for
identifying
the
minimum
flow
rate:
(1)
The
human
biological
requirement
established
in
codes
and
by
organizations
(e.g.
ASHRAE,
NBCC,
CIBSE)
and
sometimes
simply
referred
to
as
20
cfm/person
(10
L/s/person);
(2)
The
flow
required
to
maintain
human
or
equipment
temperature
limits.
ASHRAE
55
suggests
that
acceptable
temperatures
range
from
17º
to
31º
C
depending
on
the
outdoor
temperature;
(3)
The
flow
to
maintain
contaminants
(e.g.
carbon
dioxide
concentrations)
at
a
maximum
allowable
limit.
Various
tools
are
available
to
assess
natural
ventilation
and
the
use
of
one
tool
over
another
depends
on
the
driving
forces
and
critical
nature
of
the
flow.
Stack effect
Stack
effect
is
a
phenomenon
present
in
all
vertical
shafts
that
are
at
different
temperatures
from
outdoors.
This
includes
chimneys
and
buildings.
A
building’s
shafts
include
the
vertical
HVAC
risers,
elevator
and
stairwell
shafts.
The
temperature
difference
sets
up
a
scenario
where
there
is
a
density
difference
indoors
to
out.
This
pressure
difference
provides
a
driving
force
for
air
movement.
If
there
are
openings
in
the
building
façade
(even
if
they
are
very
small
cracks)
then
there
will
be
air
flow
in
at
the
bottom
and
out
at
the
top
for
a
heating‐climate
scenario.
Stack
effect
flows
in
shorter
buildings
and
chimneys
(e.g.
5
story’s)
are
a
few
Pascal’s
(PSI),
compared
to
wind
pressures
which
can
be
measured
in
10s
of
Pascal’s
(PSI).
Hence
it
is
possible
for
a
slight
wind
to
overwhelm
the
natural
stack
effect.
A
robust
design
of
natural
ventilation
in
a
building
that
uses
stack
effect
as
a
driving
force
will
be
configured
so
that
at
worst
the
wind
effects
will
be
benign
and
if
possible
they
will
assist.
It
is
important
that
all
wind
conditions
and
directions
be
considered
because
the
“prevailing”
wind
is
not
always
one
that
exists
more
than
50%
of
the
time.
You will be graded on attendance and participation in the following three areas:
Classroom Discussion /Team presentation 10%
Design Charrettes 20%
Midterm Papers (2x) 40%
Final exam & Quizzes 30%
Total 100%
Required reading:
Mechanical and Electrical Systems, by Grondzik, Kwok, Stein and Reynolds,
CIBSE, Natural Ventilation Design Guide.
Course Syllabus Page 2 of 3

Architecture 418 Spring 2012
Designing with Natural Forces
Peter Simmonds
AIVC Design Guide
References:
[1]
J.W.
Axley,
S.J.
Emmerich,
A
method
to
assess
the
suitability
of
a
climate
for
natural
ventilation
of
commercial
buildings,
in:
Proceedings
of
the
Indoor
Air,
2002.
[2]
J.W.
Axley,
Application
of
Natural
Ventilation
for
U.S.
Commercial
Buildings
–
Climate
Suitability,
Design
Strategies
&
Methods,
and
Modeling
Studies.
GCR‐
01‐820,
National
Institute
of
Standards
and
Technology,
2001.
[3]
S.J.
Emmerich,
W.S.
Dols,
J.W.
Axley,
Natural
Ventilation
Review
and
Plan
for
Design
and
Analysis
Tools.
NISTIR
6781,
National
Institute
of
Standards
and
Technology,
2001.
[4]
ASHRAE
Standard
55‐2004,
Thermal
Environmental
Conditions
for
Human
Occupancy,
Am.
Soc.
of
Heating
Refrigerating
and
Air‐conditioning
Engineers,
2004.
[5]
ASHRAE,
ASHRAE
Handbook
–
Fundamentals,
ASHRAE,
2009.
[6]
R.J.
de
Dear,
G.S.
Brager,
Developing
an
adaptive
model
of
thermal
comfort
and
preference,
ASHRAE
Transactions
104
(Part
1A)
(1998).
[7]
G.J.
Levermore,
A.M.
Jones,
A.J.
Wright,
Simulation
of
a
naturally
ventilated
building
at
different
locations,
ASHRAE
Transactions
106
(Part
2)
(2000).
[8]
ASHRAE,
Standard
62.1‐2010,
Ventilation
for
Acceptable
Indoor
Air
Quality,
ASHRAE,
2010.
[9]
ASHRAE,
Indoor
Air
Quality
Guide
–
Best
Practices
for
Design,
Construction,
and
Commissioning,
ASHRAE,
2009.
[10]
J.
Axley,
S.J.
Emmerich,
G.
Walton,
W.S.
Dols,
An
Approach
to
the
Design
of
Natural
and
Hybrid
Ventilation
Systems
for
Cooling
Buildings
(2002)
Indoor
Air
Proceedings,
in:
9th
International
Conference
on
Indoor
Air
Quality
and
Climate,
2002.
[11]
G.S.
Brager,
R.J.
de
Dear,
Thermal
adaptation
in
the
built
environment:
a
literature
review,
Energy
and
Buildings
27
(1)
(1998)
83–96.
[12]
J.F.
Nicol,
M.A.
Humphreys,
Adaptive
thermal
comfort
and
sustainable
thermal
standards
for
buildings,
Energy
and
Buildings
34
(6)
(2002)
563–572.
[13]
J.F.
Nicol,
M.A.
Humphreys,
Derivation
of
the
adaptive
equations
for
thermal
comfort
in
freerunning
buildings
in
European
Standard
EN15251,
Energy
and
Buildings
45
(1)
(2010)
11–17.
Course Syllabus Page 3 of 3