18-01-2013, 03:06 PM
INTELLIGENT BUILDINGS: THE GLOBAL FRAMEWORK
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Sustainability is a term that has become an integral part of our vocabulary. By this word
we understand the protection of the ecosystem through protection of its resources. The
economic sustainability of buildings can be divided into two parts: the investment, which
in the case of buildings and buildings stocks should be considered as long term resource
productivity problem, and the running costs. Instead of minimizing the investment cost
through low cost highly customized solutions, it is preferable to find for a given
investment the solution which has the highest durability and reusability. Solutions which
can be repaired and used in several ways have the highest long term potential. On the
other hand, solutions with low energy consumption, easy to clean, to operate and easy to
maintain have generally low running costs (and a feasibly low environmental impact at
the same time).
The social and cultural aspects of sustainability include comfort, wellbeing and safety of
the building occupants. Human health protection, which is often wrongly associated with
protection of the ecosystem, is in fact much more closely related to comfort problems
(indoor air quality, etc.). The protection of cultural resources, above all building stocks
and historic urban systems, protected biotopes and man-made landscapes gives a
common framework for architecture, city planning, regional planning and landscape
architecture. Environments which have a high cultural and social quality do not become
obsolete.
During its life cycle, which can vary from some months to hundreds of years, a building
consumes resources from nature, produces large quantities of emissions and affects the
ecosystem in many different ways. In addition to the general objective of maximizing the
quality of a building, the design process should also aim at minimizing the resource
consumption and the emissions due to the construction, operation, maintenance,
refurbishment and disposal process. One of the possible actions is to maximize the
closed loops, i.e. the reuse or recycling of building elements and materials, heat recovery
and the multiple use of water. To reduce the environmental impact means to reduce the
mass and energy flows and raise at the same time the overall quality of a building. It does
not mean to reduce the comfort level or the indoor quality.
The most important factor that threatens the sustainability of the planetary ecosystem as
we know it, is the accumulation in the atmosphere of the 'greenhouse gases'. This is
causing the planet to warm, and is producing climate changes that may be irreversible.
These climate changes are already occurring at a rate, which exceeds the adaptive capacity
of some of the earth's bio systems [1].
The most important greenhouse gas is carbon dioxide, and the increase in its
concentration is mainly because of the quantities which are being discharged into the
atmosphere due to the burning of fossil fuels.
INTRODUCTION TO INTELLIGENT BUILDINGS 8
The mechanism of the global warming effect is described briefly (see Figure 1.1.). Carbon
dioxide produced when fossil fuels are burned, but also methane, nitrous oxide, ozone,
and chlorofluorocarbons, has created what scientists call a greenhouse effect in the
atmosphere. While the solar radiation reaches the earth, one third of it is reflected back
into space and the remainder is absorbed by the earth and the atmosphere. Some of the
long-wave infrared radiation emitted back from the earth is returned to the earth by the
greenhouse gases. Like the glass in a greenhouse, greenhouse gases let in the sun's rays,
but trap heat radiated back by the earth. This causes warming of the planet. The solar
energy absorbed by natural features is balanced by the energy re-radiated from the earth
and atmosphere. Without this greenhouse canopy, the earth would be up to 30 C cooler.
Figure 1.1. The Greenhouse Mechanism
Atmospheric carbon dioxide levels were never rising above 280 parts per million until the
recent decades. Today, carbon dioxide levels are 25-28 percent higher than they were
before the Industrial Revolution, and still rising. Atmospheric CO2 levels are 365 parts
per million, and projected to double in the coming decades. Man-made sources of carbon
dioxide (fossil fuel emissions and the clearing of forests) are responsible for this increase.
Roughly five billion tons of carbon in the form of CO2 (one ton per human being) is
released into the air every year by the burning of oil, gas, and coal.
The Inter-governmental Panel on Climate Change (IPCC) reported a prediction of the
global temperature rise due to greenhouse gas emissions. According to IPCC report a
doubling of the concentration of carbon dioxide in the atmosphere compared to preindustrial
levels would lead to an average global temperature rise of as much as 4.5 °C.
Predictions regarding the impact of global warming are bound to be fuzzy. Nevertheless,
certain outcomes, the most critical being the rise in sea level due to the melting of land
based ice and the thermal expansion of sea water are certain.
The fossil fuels, namely petroleum, natural gas and coal are the energy sources on which
the European energy infrastructure is based. The energy use can be divided into three
end use segments:
Transportation
Residential and commercial buildings
Industry
Each of these sectors consumes about one-third of the total energy use. More specifically
the total final energy consumption in the EU in 1997 was about 930 Mtoe. A simplified
INTRODUCTION TO INTELLIGENT BUILDINGS 9
breakdown of this demand shows the importance of buildings in this context: 40.7% of
total energy demand is used in the residential and tertiary sectors, most of it for buildingrelated
energy services. It should also be pointed out that approximately 10% of the
consumed energy in buildings comes from renewable energy sources (RES). Space
heating is by far the largest energy end-use of households in Member States (57%),
followed by water heating (25%). Electrical appliances and lighting make up 11% of the
sector’s total energy consumption (Figure 1.2.). For the tertiary sector (Figure 1.3) the
importance of space heating is somewhat lower (52% of total consumption of the
sector), while energy consumption for lighting and "other" (which is mainly office
equipment) are 14% and 16%, respectively.
On the other hand, there is increasing international concern with climate change, and the
targets agreed by the European Union under the Kyoto Protocol to reduce emissions of
greenhouse gases in 2010 by 8% compared to 1990 levels represent a real challenge. In
the Green Paper three major points emerged concerning the European Union and its
energy strategic issues [4]: