Università IUAV di Venezia, Environmental Building Physics– Introduction to sustainability
Integrated Studio 1 – Master Degree in Architecture and Innovation
Sustainable Design
Sustainable Design is a more efficient process consisting in an integrated
approach to the definition of architectural form and able to:
•
Sustanible and
Climate Responsive Design:
Principles
minimize the impact on the environment;
• minimize energy consumption;
• optimize the quality of indoor environment;
• optimize the use of resources;
• optimize the long-term costs for operation
Fabio Peron
Università IUAV - Venezia
Sustainable Design: three level of action
3
Mechanical Systems
Passive systems
2
Daylight
Natural ventilation
solar heating
…………..
Basic design:
1
Envelope
Form
orientation
………………
and maintenance,
• decreasing the weight of HVAC systems
Building as an
environment moderator
A building’s primary function
is to provide shelter from
the elements, as a function
of CLIMATE.
To function as a moderator of
the environment and to
satisfy all other
requirements, a building
envelope must provide
control of:
1. heat flow
2. air flow
3. movement of water as
vapour and as liquid
4. solar and other radiation
Urban Ecology Centre, Milwaukee
Sustainable Design: energy efficiency
Climate Responsive Design: exposition
Sun is in different positions as a function of hour, latitude, season
Climate Responsive Design: exposition
Annual radiation on a surface facing South at 45°N
Climate Responsive Design: exposition
Annual radiation on a vertical surface at 45°N
Climate Responsive Design: exposition
Climate Responsive Design: exposition
With good orientation the need for heating
and cooling in the building is reduced.
The main orientation of the building should
be within 30° of south: high level of
radiation during winter, low level during
summer.
Houses orientated east of south will
benefit more from morning sun, while
those orientated west of south will catch
late afternoon sun delaying the evening
heating period.
For ideal solar access southeast to
southwest aspects of the building are left
open to the sun to allow for maximum
effects of passive solar heating and day
lighting
Climate Responsive Design: exposition
Climate Responsive Design: exposition
South Exposition
Winter: sun is low above the horizon, maximum solar
radiation, high level of energy income
Summer: sun has a high altitude angle, low level of
radiation low enery load expecially with little overhangs
30-40% glazed surface on South wall gives good level of
solar income during winter and limitated summer
overheating
Optimal distance between buildings
Position a new build or extension so it doesn’t block the
natural sunlight of surrounding buildings. Winter solistice
can be considered for analysis.
Optimal distance between buildings
South positioning of openings
Wind action
Sun access
Acoma pueblo – New Mexico
Different wind exposition conditions
Wind action
Wind action
Wind is useful for
ventilation however
Wind is useful for
shelter is important to
ventilation however shelter
avoid excessive wind
is important to avoid
speeds.
excessive wind speeds.
Shelter can be provided
Shelter can be provided by
by several means; other
several means; other
buildings, natural
buildings, natural vegetation
vegetation or wind
or wind breaks.
breaks.
Deciduous trees also provide
Deciduous trees also
shading from the sun in the
provide shading from
summer
the sun in the summer
and let light in when the
and let light in when
branches are bare in the
the branches are bare
winter.
in the winter.
Natural ventilation
Envelope modelling
The depth of a space
for natural ventilation
Plan form has a
significant role in the
design for energy
efficiency.
Deep plan forms result
in the building being
reliant on mechanical
cooling and artificial
lighting.
Considering solar radiation: wide
south facing surfaces for the
collection of winter radiation
Considering the wind: llimit north
facing surfaces exposed to winter
cold winds
The result modelling the surfaces
can be this
Envelope modelling
Envelope modelling
Modeling considering only winter
needs
Is also possible to differentiate the
envelope with various level of
insulation.
But arrives also the summer:
The protection of South surfaces is
needed; appears the Porch
Considering also the summer conditions
during the afternoon-evening are also
needed shelters facing west
Is possible to vary the form
Climate Responsive Design: form
Climate Responsive Design: volume-surface ratio
Compact forms
Climate Responsive Design: volume-surface ratio
Climate Responsive Design: volume-surface ratio
Different ways to aggregate
More compact - smaller losses:
Same volume with reduced
dispersion surface.
Q= U A (ti-te)
More compact smaller losses:
Sustainable design: compactness, S/V ratio
Climate Responsive Design: volume-surface ratio
Climate Responsive Design: volume-surface ratio
Climate
Responsive Design:
functions distribution
Casbah di Algeri
Casbah di Algeri
The most frequently used rooms
should be placed on the south
side of the dwelling ( e.g. living
room) Rooms used less often or
those that do not benefit from
sunlight should be placed to the
north of the building ( e.g.
hallways, bathrooms, utility
rooms, stores). Also they should
Tunisi
have smaller windows to
minimize heat loss.
Climate Responsive Design: functions distribution
Climate Responsive Design: functions distribution
Casbah di Algeri
Casbah di Algeri
Tunisi
Potential design response to vertical zoning of building (Stein)
Climate Responsive Design:
absorptivity and emissivity
Absorptivity is a material property that
determines the fraction of radiation
that is absorbed by a surface
Bagdad, seasonal migration in the family house
Climate Responsive Design:
absorptivity and emissivity
short waves
Emisivity is a similar property that
determines the radiation that is
emitted by a surface
As solar radiation is at a higher
temperature (5,777 K) than can be
attained by a surface on earth, the
wavelength will be different (usually
infra-red) and thus the values will be
different
St. Thomas University, Houston
St. Thomas University, Houston
long waves
Climate Responsive Design:
absorptivity and emissivity
Climate Responsive Design:
absorption and emissivity
St. Thomas University, Houston
Climate Responsive Design:
absorption and emissivity
St. Thomas University, Houston
Climate Responsive Design:
absorption and emissivity
Infra Red exchange with
sky vault (-40°C, -50°C)
Traditional buildings in Mediterranean area (Greece)
Climate Responsive Design: absorption, emissivity
Climate Responsive Design: around the building
Cupole e volte aumentano la superficie di scambio con la volta celeste e la velocità
del vento per effetto venturi.
Falling leafs plantation
Borujerdi-ha khashan – Iran
Oasi del Fayyun – Egitto
Pergola
with falling leafs
Qa’a – Iran
Climate Responsive Design: heat storage
Climate Responsive Design:
heat capacity, thermal mass
Specific heat
• the amount of energy required
for a unit temperature increase
in a unit mass of material
• Unit: W h kg-2k-1
A comparison between materials for reaching a storage capacity of 5700 kJ with a temperature
increase of 10 K
Thermal mass works by storing heat and releasing it several hours later. This has
advantage in warm periods because the internal air temperature does not rise
as fast, maintaining thermal comfort. Instead the heat is stored in the fabric of
the building. At night when the outside temperature is lower, it vents the heat
stored in the building so the building is cooled and ready to store heat again the
next day. Thermal mass is simply dense material. It is achieved by providing the
building will high levels of insulation and/or dense materials. Thermal mass can
be used in winter or summer to either heat or ventilate a space
Heat capacity
• The amount of heat energy
required for a unit temperature
increase in unit area
• Denoted by Q
• Unit: W h m-2K-1
• Thickness x specific mass x
specific heat
The heat capacity is connected to the time lag and decrement factor of an
envelope element
Climate Responsive Design: around the building
Climate Responsive Design:
heat capacity, thermal mass
Specific heat
•
the amount of energy required for
a unit temperature increase in a
unit mass of material
•
Unit: W h kg-2k-1
Heat capacity
•
The amount of heat energy
required for a unit temperature
increase in unit area
•
Denoted by Q
•
Unit: W h m-2K-1
•
Thickness x specific mass x specific
heat
Materials can absorb or reflect the solar radiation
Evergreen on West, falling leafs on South
Climate Responsive Design:
heat capacity, thermal mass
St. Thomas University, Houston
The heat capacity is connected to the time lag and decrement factor of an envelope
element
Climate Responsive Design:
heat capacity, thermal mass
polistirene espanso
35
1210
sughero
120
1800
42,35
216
lana di legno
400
2000
800
gomma
1200
1400
1680
legno-quercia
750
2500
1875
legno-pino
550
2720
1496
intonaco sabbia-gesso
1600
1000
1600
intonaco sabbia-cemento
1800
1000
1800
intonaco sabbia-calce
1600
1000
1600
mattoni
1850
850
1572,5
terreno
1600
1900
3040
vetro
2500
750
1875
calcestruzzo
2300
1000
2300
arenaria
2600
793
2061,8
basalto
2850
1000
2850
pietra calcarea
2200
1000
2200
terra cruda - adobe
1020
1200
1224
acqua-liquida
1000
4186
4186
paraffina
St. Thomas University, Houston
900
2890
2601
Thermal regulation: green roof
•
•
•
•
Diminution of paved surfaces
Production of oxigen and consumption of carbon dioxide
Absorption of dust
Reduction of day-night temerature variation
Thermal regulation: green roof
Thermal regulation: green roof
• Reduction of humidity variations
• Acoustic insulation
• Limitation of surface washing
Thermal
greenparete
wall verde
Involucroregulation:
termoregolato:
Superfici vetrate
Glazings
On North, East and West glazing
surface would be sized to
guarantee good level of daylight.
On North facing glazings is
important have a good level of
insulation and limit window
dimensions.
Buildings in Brasilia
VITRUVIO, DE ARCHITECTURA, LIBRO VI:
“ORA BENE, SE É UN DATO DI FATTO CHE I PAESI DIFFERISCONO TRA LORO E HANNO
CLIMI DIVERSI, DI TAL FORMA CHE PERSINO GLI UOMINI NATI IN QUEI LUOGHI
DIFFERISCONO TRA LORO IN MANIERA NATURALE NELLA PROPRIA CONFORMAZIONE
FISICA E MENTALE, NON POSSIAMO ESITARE NEL FARE LE NOSTRE CASE ADATTATE A LE
PARTICOLARITÁ DI NAZIONI E RAZZE, PERCHÉ É LA STESSA NATURA AD INDICARLO”.
Glazings
Glazing Type
• Use clear or low-e gas-filled insulating glazing
• Use higher Solar Heat Gain Coefficient (SHGC) on south-facing glazing, or use
clear south-facing glazing
• Use lower SHGC on east, west & north-facing glazing
• Avoid un-shaded overhead glazing
• Use high clerestory or transom windows, instead of skylights, to increase daylight
penetration & facilitate shading
• Minimize large expanses of west-facing windows and glazing
Glazing Area
•
•
•
•
•
•
Allocate 50% of the overall glazing to walls within 30 degrees of south
Allocate 50% or less of window area to the north, east and west faces
Provide 10-15% of floor area in south-facing glazing
Less glazing if building constructed of lightweight materials
More glazing if building constructed of heavier materials
Limit east or west-facing glazing to less than 5% of floor area
On south facing walls dimensions have to
gurant ee the inlet of solar radiation during
winter but with shading systems
Daylight:
obstructons
Daylight
• If a window is to be provided with adequate daylight
then obstructions should be no higher than 25
degrees above the horizon (see diagram).
• A room has a daylit appearance if the area of glazing
is at least 1/25th of the total room area.
• Areas of a room where there is no direct view of the
sky are likely to have a low level of daylight.
Glazing ratio and Window orientation
Windows allow for daylight and solar penetration, which
reduces the need for artificial light and heating
requirements. However having too many windows can
cause overheating.
•
•
•
The optimum glazing ratio is 30-50% for vertical
surfaces and 20% for rooflights.
South facing windows get the most amount of day
lighting.
West facing windows cause problems because they
let light in the space in the evening when the room
may already be warm through convection of heat
from other rooms.
In parts of the building where natural light from
windows cannot be reached, consider installing light
steals such as roof lights, light tubes and wells.
Availability of natural day light within a building reduces
the amount of energy required to provide electric
lighting during daylight hours.
Shading
Shading
Preventing the sun’s rays from entering the building.
To prevent rooms from overheating it is important to shade
windows from direct sunlight in the summer months.
External blinds are more effective than internal blinds as
they prevent the sun’s heat entering the room.
The basic idea is to insulate the outside from the inside,
and to prevent direct sunlight from entering the space.
Roof overhangs and brisesoleil (louvers) can be used to
allow daylight to enter without the direct rays from sun.
References
Fathy: http://www.unu.edu/unupress/unupbooks/80a01e/80A01E00.htm
Gaut: http://collections.infocollections.org/ukedu/en/d/Jsk02ce/