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PASSIVE AND ACTIVE HEATING AND COOLING M.
Santamouris Group Building Environmental Studies,
University of Athens, Athens, Greece
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BUILDING SUSTAINABILITY AN OXYMORON OR A
PERSPECTIVE
Buildings are systems that import energy and
resources and produce degraded energy and matter
that has to be assimilated by the surrounded
area. Thus, is hard to consider buildings as
sustainable systems . Urban Buildings present
important advantages and should not be considered
as places that only generate environmental cost.
It may provide high quality living conditions
with lower levels of energy use, waste, pollution
and in general low environmental impact, than the
wealthy rural or suburban areas. .
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BUILDING SUSTAINABILITY AN OXYMORON OR A
PERSPECTIVE
There are two basic criteria for ecological
sustainability of buildings -         To
consumption renewable and replenishable energy
and resources that should not exceed their
production in nature, and  -         The
production of degraded energy and matter by the
buildings must not exceed the assimilative
capacity of local ecosystems or the ecosphere
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BUILDING SUSTAINABILITY AN OXYMORON OR A
PERSPECTIVE
Building Environment has to satisfy five broad
categories of environmental goals   To
provide the environmental conditions that can
ensure health of citizens and reduces
vulnerability of the population. This includes
basic infrastructures and services like adequate
provision of water, sanitation, garbage
collection and drainage for all the urban area
and citizens. To reduce the risk of chemical
and physical hazards in the every day life To
provide citizens with a high quality urban
environment that protect the natural and cultural
heritage, provide comfort and the necessary urban
spaces for the well being of citizens To reduce
as much as possible the shift of the
environmental load and cost generated by the
cities to the inhabitants and ecosystems
surrounding the city To ensure that the
consumption of resources and goods and the
corresponding generation of matter and degraded
energy are compatible with the limits of the
natural capital and do not transfer environmental
load and cost to future generations or to other
human groups
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Main priorities are Improve the Urban
Microclimate, fight heat island and reduce the
energy needs for cooling. Use of sustainable
energy supply systems for buildings based on the
use of renewable sources like solar and biomass
district heating and cooling. Use of demand side
management techniques to control and regulate the
energy consumption of big consumers. Integration
of passive and active solar systems in the
envelope of new and existing buildings, and use
of high energy performance supply and management
equipment Application of appropriate city
planning techniques when new settlements are
designed.
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A series of institutional, economic and
regulatory actions are foreseen as important.
The development of a new more efficient
legislative frame on the energy performance of
buildings. Integration of the environmental
cost in the price of goods and services
Adoption of green consumption principle by the
urban citizens Adoption of the principle of
fair trade by the citizens and their
institution in order to reduce exploitation of
people mainly in less developed countries.
Application of new principles on the production
and management of energy related systems and
components, like the principle of natural
capitalism. Strength the involvement of local
authorities on the production, maintenance and
management of the energy systems on the city
level
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Improvement of the ambient microclimate in the
urban environment involving the use of more
appropriate materials, increased use of green
areas, use of cool sinks for heat dissipation,
appropriate layout of urban canopies, etc., to
counterbalance the effects of temperature
increase, is among the more efficient
measures. Such a strategy, adopted by the
Sacramento Municipal Utility District, (SMUD),
has proved to be very effective and economically
profitable. It has been calculated that a
megawatt of capacity is actually eight times more
expensive to produce than to save it. This
because energy saving measures has low capital
and no running cost, while construction of new
power plants involves high capital and running
costs
IMPROVING THE URBAN MICROCLIMATE
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Simple materials used in buildings are
characterized by various albedo values, that
determine the albedo of a city. Increase of the
albedo has a direct impact on the energy balance
of a building. Large scale changes on urban
albedo may have important indirect effects on the
city scale Computer simulations show that white
roofs and shade trees in Los Angeles, would lower
the need for A/C by 18 percent or 1.04 billion
killowatt-hours, equivalent to a financial gain
close 100 million per year.
IMPROVING THE URBAN MICROCLIMATE
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Trees and green spaces contribute to cool our
cities and save energy. Trees can provide solar
protection to individual houses during the summer
period while evapotranspiration from trees can
reduce urban temperatures. Trees also help
mitigate the greenhouse effect, filter
pollutants, mask noise, prevent erosion and calm
their human observers The American Forestry
Association, estimated that the value of an urban
tree is close to 57000 for a 50 years old
mature specimen.This includes a mean annual value
of 73 for air conditioning, 75 for soil
benefits and erosion control, 50 for air
pollution control and 75 for wildlife
habitats. The impact of trees on the energy
consumption of buildings is very important. As
reported by the National Academy of Sciences of
United States, the plantation of 100 million
trees combined with the implementation of light
surfacing programs could reduce electricity use
by 50 billion kWh per year, which is equivalent
to the 2 per cent of the annual electricity use
in the US and reduce the amount of CO2 dumped in
the atmosphere by as much as 35 millions of tons
per year.
IMPROVING THE URBAN MICROCLIMATE
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Sustainable energy supply systems and mainly the
use of district heating and cooling systems based
on the use of renewable energies like solar and
biomass or the use of waste heat, is the major
tool to introduce clean and sustainable energy in
cities. Produced energy may supply the
residential sector, industry, urban agriculture,
and any other sector requiring hot or cold water.
SUSTAINABLE ENERGY SUPPLY SYSTEMS
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District heating and cooling installations using
renewable energies are constantly increasing in
Europe. Annual energy growth of the renewables
contribution is close to 10-15 . Renewables
contribute almost the 9.5 of the primary
energy, while waste heat offer almost 12 . In
many European countries the potential for use of
renewables for district heating systems is very
high, while the number of settlements supplied by
district heating networks is continuously
increasing. In Sweden more than 50 of the
energy is delivered by waste heat and renewable
energy sources,
SUSTAINABLE ENERGY SUPPLY SYSTEMS
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District cooling systems present a number of very
important advantages. These have to do with the
dramatic decrease of peak electricity load. As
buildings served by the district cooling network
do not present peak cooling demand at the same
time, the peak load line of district cooling
systems is much smoother and thus there is no
need to over design the cooling capacity of the
network. This results in substantial reductions
of the capital and operational cost. In parallel,
room and central air conditioning systems are
designed to meet the peak cooling conditions.
Thus, for more than 90 of the operation period
perform out of the nominal conditions, and for
sure their efficiency is quite reduced.
SUSTAINABLE ENERGY SUPPLY SYSTEMS
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SUSTAINABLE ENERGY SUPPLY SYSTEMS
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Demand side management techniques may be the more
appropriate tools to reduce the peak and total
energy demand, in cities. During the recent
years, some forms of demand side management
techniques have been extensively used by the
European utilities . Apart of the use of
sustainable district heating and cooling systems,
five types of demand side management actions can
be identified DSM1. Use of more energy
efficient air conditioners and heating devices
that implies better performance and better design
and integration to the building. DSM2.
Application of advanced control systems like
inverters, fuzzy logic in order to take into
account the operational profiles of urban
buildings, like the highly intermittent
occupation of residential and commercial
buildings in urban areas .
DEMAND SIDE MANAGEMENT
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DSM3. Direct load control like remote cycling, by
the utilities on the cooling usage as on other
usage. This techniques is widely applied during
peak periods on a few millions of appliances room
air conditioners in the US. By limiting the
available duty cycle during peak periods,
utilities can reduce significantly the peak
demand. Attention has to be given on consumers
comfort. DSM4. Improvements on the building
design to decrease their heating and cooling
load. This may involve actions on heat and solar
protection, heat modulation and dissipation of
excess heat in a lower temperature environmental
sink. DSM5. Use of cogeneration techniques. This
type of distributed generation of electricity
possibly cold/hot water or steam can reduce peak
transportation costs and use of fuel.
DEMAND SIDE MANAGEMENT
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The adaptation of urban buildings to the specific
environmental conditions of cities in order to
efficiently incorporate solar and energy saving
measures and counterbalance the radical changes
and transformations of the radiative, thermal,
moisture and aerodynamic characteristics of the
urban environment is a major priority. This
incorporates appropriate sizing and placing of
the building openings, to promote solar energy
utilization, enhance air flow and natural
ventilation and improve daylight availability,
integration of photovoltaics as well as use of
passive cooling techniques to decrease cooling
energy consumption and improve thermal
comfort. Passive solar heating, cooling and
lighting techniques have reached a high degree of
technical maturity. Large scale applications,
especially in new settlements, have shown that
very high energy gains can be achieved while the
thermal and visual comfort as well as indoor air
quality are very satisfactory
PASSIVE AND ACTIVE SOLAR SYSTEMS FOR BUILDINGS
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Retrofitting of buildings is the major mechanism
to improve the energy and environmental quality
of existing buildings. In most European
countries, retrofitting and refurbishment of
buildings consist a major economic activity in
comparison to new constructions. In particular,
retrofitting of houses and offices of the pre and
immediate post - war offices and residences is a
very important market presenting extremely high
potential for energy conservation.
PASSIVE AND ACTIVE SOLAR SYSTEMS FOR BUILDINGS
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PASSIVE AND ACTIVE SOLAR SYSTEMS FOR BUILDINGS
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PASSIVE AND ACTIVE SOLAR SYSTEMS FOR BUILDINGS
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PASSIVE AND ACTIVE SOLAR SYSTEMS FOR BUILDINGS
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PASSIVE AND ACTIVE SOLAR SYSTEMS FOR BUILDINGS
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PASSIVE AND ACTIVE SOLAR SYSTEMS FOR BUILDINGS
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New Designs have decreased the heating demand as
low as 15 to 30 kWh/m2/yc
PASSIVE AND ACTIVE SOLAR SYSTEMS FOR BUILDINGS
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New Designs have decreased the cooling demand as
low as 5 to 10 kWh/m2/y
PASSIVE AND ACTIVE SOLAR SYSTEMS FOR BUILDINGS
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• An economy wherein consumers obtain energy
  services and flows by leasing and renting goods
  and systems than buying them, offers many
  opportunities.
• Higher efficiencies as systems are better
  maintained
• Avoidance of oversizing of the systems
• Less wastes
• Less use of primary materials
• Increased employment
• Many companies like Carrier, Agfa Gaevert have
  already applied such ideas and have increased
  their profits

NEW TRADE AND COMMERCIAL MECHANISMS
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CONCLUSIONS
The energy consumption of the building's sector
is considerably high and is expected to further
increase because of the improving standards of
life and increase of the world population.
Satisfying the increased energy needs,
particularly in developed countries, without to
compromise the atmospheric environment, clean and
low cost systems and techniques have to be
employed. Passive and active solar techniques
combined with advanced conservation technologies
seem to be the more appropriate and efficient
solution to this problem.
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CONCLUSIONS
Appropriate future planning should consider that
the built environment is not just a collection of
buildings, but it is in fact the physical result
of various economic, social and environmental
processes strongly related to the society
standards and needs. Economic pressures related
to property and labour market, investment and
equity, household income and the production and
distribution of goods, in combination with social
aspects related to culture, security, identity,
accessibility and basic needs, and finally, in
association with environmental influences related
to the use of land, energy and materials, define
and determine the built environment we live in,
and will determine the future of solar
technologies as well
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