1.
Single
sided ventilation can be effective for building widths up to twice the
floor-to-ceiling height.
2.
Well
designed windows are critical for minimum fresh air inflow in winter (trickle
ventilation to prevent cold draughts).
Horizontal pivoted and vertical sash windows have good ventilation
capacity, air enters at low level and leaves under buoyancy effects at high
level. Side or vertical pivoted windows are less effective.
3.
The capital cost of the mechanical services will be low
in buildings employing natural ventilation but considerably more may need to be
spent on the building fabric to achieve good thermal characteristics.
4.
A
naturally ventilated building has simple HVAC systems and as a consequence has
a low energy consumption. There is no
energy used for fans – air movement is achieved through well-designed opening
windows or more sophisticated ventilation stacks and flues which make use of
wind and buoyancy effects. The simplest of systems yields the lowest energy
consumption
5.
Windows and vents
which are to use for a single sided ventilation or cross flow system must be
considered in terms of embodies energy the embodied
energy contained within the materials.
A window frame which is made of aluminium and is specially transported
from Germany to Britain to be installed in a building would have a high
embodied energy that a window which was manufactured and installed within the
UK.
6.
Acoustic such as from outside the building very
difficult to control with single sided ventilation as a large amount of noise
will enter the building from opening a window.
Similarly the same noise may be able to enter through open vents. Depending on the size of vents and windows
noise may be generated from air moving through the opening. Noise reduction in single sided, cross flow
and stack ventilation can be achieved by good design of the system.
7.
Condensation can be a factor in natural and basic
mechanical ventilation systems when the air, being vented or forced into a
building, has a high humidity and the temperature of internal surfaces are cold
thus causing moisture to condense to water on the surface.
8.
Single sided ventilation is only appropriate in small
areas. Occupants
near the perimeter will have control for single-sided ventilation and will
often feel the full benefit of the system before occupants at the back or
centre of a room. This system is
sometime not effective in providing adequate thermal comfort.
9.
Cross
flow ventilation can be effective for building widths up to five times the
floor-to-ceiling height.
10. Spatial room layouts are required in order to maintain
crossflow of ventilation air. The
position of large objects in a room can negate the effects of moving air in a
crossflow pattern.
11.
Depending on the design of the system, cross flow
ventilation can maintain a reasonable level of thermal comfort for the
occupants. However, there is a problem
for people close to the points of fresh air intake. If the occupant is static
for any long periods they may suffer from draught effects, especially since a
reasonable flow of air is required to induce the flow of air across a large
area. The indoor air quality can suffer
by this system as contaminated air is drawn across occupants’ bodies. Air quality can be a problem in urban sites as
filtration is difficult.
12.
Stack Ventilation can be effective for buildings with overall heights up
to five times the floor-to-ceiling height, measured between the air inlet and
the stack.
13.
The
pressure generated by stack ventilation is too low for conventional air
filtration.
14.
Stack
ventilation can provide good thermal comfort and indoor air quality for
occupants. It achieves this by bringing
fresh air in at low level, cooling the
occupant, and as the warmed air rises (natural buoyancy) takes away any
contaminants in the air at high level. Air quality can be a problem in urban
sites as filtration is difficult.
15
More
building space is required to accommodate air handling plant and distribution
ductwork.
16.
Ducted distribution will permit ventilation
heat recovery, filtration and humidification
17.
Capital
costs are higher than for naturally ventilated systems due to the additional
expense of supply and extract fans, distribution ductwork and controls. The installation costs of the supply and
extract systems can be costly if there are long duct runs and complex
integration of systems into the building.
18.
With
a supply and extract system there is a demand for electrical energy to power
the fans. The electrical demand is
dependent on the size of the fans, the number of hours the fans run and speed
control on the fans to minimise the fan energy. There is an energy penalty for operating with high air flow rates
from the fans in the summer.
19.
Embodied
Energy – The embodied energy used in the manufacture of mechanical ventilation
systems is negligible to that of the energy consumed during the use phase
20.
Fan
energy can be significant, particularly if control of the operational hours is
poorly set-up. Design of a low energy
system will be effected in a negative way by fan operation has been poorly
controlled or there has been insufficient attention to the detail of the air
distribution pressure drops.
21.
The
design of the system is a very important factor in achieving good
acoustics. Where there are pressure
drops and large flow rates there can be noise associated with the supply and
extract system. This can be reduced
with acoustically insulated ducts and silencer baffles. However, it is primarily the designers responsibility
to ensure good acoustics from ventilation systems.
22.
Condensation can be a factor in basic mechanical
ventilation systems when the air, being vented or forced into a building, has a
high humidity and the temperature of internal surfaces are cold causing the
moisture to condense to water on the surface.
However, a
ducted supply and extract system can be used to supply winter humidification to
the space.
23.
A good filtration standard can be achieved with supply
and extract and hollow core ventilation, however, the penalty for higher air
cleanliness is capital cost for filters, maintenance costs and increased energy
required for fans. When compared to
natural ventilation solutions; supply and extract and hollow core can provide
more predictable performance giving improved environmental quality. In winter fans can operate with minimum
fresh air rates to control odour and stale air formation.
24.
Thermal mass can be used to cool or heat space and is
governed by the surface area which is available for heat exchange, the heat
transfer co-efficient between air and mass and the contact time. By moving air
through the structure itself, instead of just over it, has the potential to
improve all three factors and thus improve the effectiveness of available mass.
The system can be used throughout the year for thermal storage:
·
in summer, cooling is stored with night-time ventilation
of the mass, to be used the next day to cool the supply air before passing it
to the occupied space
·
in winter, waste heat from internal gains or heating can
be stored in the fabric to be re-used when the building has a heating demand.
25.
Hollow core ventilation systems have to be designed into
the building’s structure at an early stage as attempting to retrofit a
ventilation system capable of using a building’s thermal mass can be
impossible. The system requires
electrical energy to operate control systems and fan units. However, this system uses the natural
thermal storage ability of the building to heat or cool according to the
internal environment’s requirements and, hence, can reduce heating demand in
winter.
26.
It may be necessary to use condensation control on the
system to ensure the likelihood that moist supply air does not come into
contact with cold surfaces. This is
especially important in the design of this system as it uses surface energy to
cool or heat space.
27.
The system can be used throughout the year for thermal
storage:
·
in summer, cooling is stored with night-time ventilation
of the mass, to be used the next day to cool the supply air before passing it
to the occupied space
·
in winter, waste heat from internal gains or heating can
be stored in the fabric to be re-used when the building has a heating demand.
This system can optimise the thermal comfort
of the building.
28.
A
building can use a mixture of mechanical and natural ventilation, otherwise
known as mixed mode ventilation, to attain the best of both worlds. There are a number of design considerations
which could be used to optimise cooling of the building. The basic principle of this system is that
natural ventilation is used for Spring and Autumn with mechanical ventilation
used in the summer where necessary to augment the natural system. Mechanical ventilation can be used at night
to purge the building of heat build up from day use.
29.
A
special consideration for the system is to use exhaust air heat recovery.
30.
The
installation cost of this system can be minimised if natural ventilation is
designed to be used more predominantly than mechanical ventilation.
31.
With
a mixed mode system the requirement for fans can be reduced which means a
decrease on electrical demand. If heat
recovery is employed this can minimise the heating energy consumption.
32. The embodied
energy may be lower for a system such as this as the amount of mechanical ventilation
in the system is likely to be less for a building which uses purely mechanical
ventilation. The reason for this would be a reduction in ductwork and fans.
However, their may be an increase in the embodied energy associated with
controls in this system as it would require reasonably intelligent controls to
ensure effective changeover between systems.
33. The control of acoustics with this system may
be more difficult to control than the previous mechanical ventilation systems
described. As mixed mode systems employ
natural ventilation as a cooling strategy achieving good acoustics becomes more
complex. If opening windows or vents is
part of the natural ventilation strategy it is very difficult to control the
noise of airflow through the building.
34. Problems can be caused with opening windows if the occupants are
not clearly informed as to when the system changes over from mechanical to
natural ventilation, but there are psychological advantages in allowing
occupants control over window opening for at least part of the year. If the mixed mode system is designed
properly it will provide a comfortable internal environment for occupants with
good indoor air quality and thermal comfort.
35. Where daylight is present, the photocell sensors can interact with
the ballasts to fully utilise available natural light varying the luminance
continuously, with changes in natural lighting, to achieve a constant
illuminance on the working plane. The
benefits of this strategy vary from season to season.
36.
A high level of natural lighting must exist in the space in order for the
daylight sensing strategy to be
effective.
37. Daylight sensing
control is a very expensive lighting control strategy.
38.
It has been suggested that Daylight sensing control can save as much as 75% by whom of the running costs of fluorescent and
triphosphor lighting.
39. Daylight sensing offers relief to eyestrain. Eyestrain occurs when the muscle of the eye
continually adjusts to the brightness. However,
with daylight sensing it is the artificial lighting which continually adjusts
so that a constant illuminance is achieves for the occupant.
40. Occupancy sensors react to variables like heat or motion by turning
lights on or off. They turn lights on when the presence of people is detected;
then, after an adjustable predetermined period during which people are not
detected, turn them off. Because occupancy sensors prevent lights from being
left on when they are not in use, they conserve electricity. Occupancy Sensors
are most effective for those rooms or spaces which are not used for long
periods of the day. The benefits of occupancy sensors is that they are not
dependent upon users switching off lights which very often they forget to do.
PIR sensors are often effectively installed in toilets.
41. Occupancy sensors should not be installed in areas or spaces where
the health and safety of occupants are put at risk eg areas where there is
machinery operating. They are most
appropriate for controlling both incandescent and rapid star fluorescent lamps.
42. Passive Infrared
Sensors (PIR) are the most common type. They detect infrared heat energy
emitted by people. Triggering occurs when they detect a change in infrared
levels, as when a warm object moves in or out of view of one of the sensor's
"eyes." PIR sensors are passive: they detect radiation but do not
emit it. The cost of PIRs (not including installation) range from around £20 to
£70 depending on the type ie wall mounted or ceiling mounted.
43. Occupancy Sensors have the potential to significantly reduce
lighting energy consumption in proposed commercial and industrial
facilities. In a new building the
savings produced by occupancy sensors can be calculated by the amount of hours
the lights will be off according to occupancy against conventional lighting
systems on or off and reliant on human control.
44. It has been suggested that Daylight sensing control can
give potential energy savings up to 50% (Best Practice Programme) of the
running costs of fluorescent and triphosphor lighting.
45. High Frequency
(HF) electronic ballasts instead of conventional magnetic ballasts provide more
light output with less wattage and run much quieter and cooler. HF ballasts are most effective in reducing
energy consumption when used with energy efficient lamps.
46. The cost or an HF ballast is difficult to quantify for all
types of lighting. However, as a
guideline; three lamps, 4ft in size, fitted onto a triple HF ballast would cost
a maximum of £30 per triple ballast.
47. Fitted with HF ballasts, lamps would consume only 75% of the
energy they would consume with ordinary fittings.
48. HF ballasts produce
tens of thousands of pulses per second, causing phosphor to drop by 2%, and,
hence, light output to drop marginally from lamps. By comparison, traditional ballast produce 120 pulses per second
causing phosphor output to drop drastically resulting in lower illuminance
levels from lamps. With HF ballasts the
light flickers, which can sometimes be noticed by the naked eye in conventional
ballasts, does not occur.
49. Compact fluorescent (CF) lamps come in many shapes and sizes
and almost any fixture can be retrofitted which gives the building occupier
scope to change lamps design. They are
most effective and efficient where lights are on for long periods of time.
50. The ambient temperature can have a significant effect on
light output and lamp efficiency. The temperature of the coldest spot on the
surface of the lamp is where mercury vapour will condense to liquid form, and
this temperature (minimum lamp wall temperature) controls the vapour pressure
inside the lamp. The optimum lamp wall temperature for CF lamps is generally
38C. At temperatures below the optimum, mercury vapour will condense at the
cold spot, reducing the number of atoms available to emit UV radiation and,
hence, light output reduces.
51. A CF lamp has a life of around 8000 hours, hence reducing
the capital cost of changing the lamps against incandescent lamps. A CF Lamp is
a more expensive lamp than an incandescent lamp.
52. CF lamps typically reduce electrical use by around 25% on
incandescent lamp (conventional lamps with tungsten filament) use. CF lamps have a luminous efficacy (uses less
power in to provide light) of 70 lumens per watt.
53. For reasons of lumen maintenance, rare earth phosphors are
required in CF lamps.
54. Compact fluorescent lamps provide a colour-rendering factor
of 82 out of 100. They have a cool operating temperature so they do not enhance
heat gains in an area and thus do not impact on thermal comfort in an area.
55. Compact fluorescent lamps provide a
colour-rendering factor of 82 out of 100.
They have a cool operating temperature so they do not enhance heat gains
in an area.
56. A triphosphor lamp
has a life of between 12,000 and 18,000 hours, hence, reducing the capital cost
against continually changing the lamps against shorter life-span lamps. A
triphosphor lamp is more expensive than a CF lamp.
57. Triphosphor Lamps use 10% less electricity than a CF
lamps. The Triphosphor Lamp has a
luminous efficiency of 100 lumens per watt.
58. A higher content of rare earth phosphor is required in
triphosphor lamps than that of CF lamps. As the colour rendering index of
various types of triphosphor lamps increases so to does the phosphor
content. This inevitably has an adverse
effect on the embodied energy of this type of lamp.
59. The colour rendering index (reflects how accurate the colour
of an object can be determined under a given light source) for T8 Triphosphor
lamps is 85 out of 100.
60. T8 Triphosphor
lamps colour rendering index (reflects how accurate the colour of an object can
be determined under a given light source) of 85 out of 100.
61. Prismatic Panels
Prismatic Panels
are a shading systems using diffuse skylight.
Prismatic panels can be attached to vertical windows and skylights. The illustration above shows that prismatic
panels prevents direct solar radiation from entering the building whilst
accepting diffuse skylight. Prismatic
panels most effective use is in providing glare protection.
62.
The view to the outside environment can be restricted if the prismatic panels
cover the entire façade. Prismatic Panels are effective in all climates.
63.
Result in reduced solar heat gain and, hence, cooling and reduction in amount
of artificial lighting.
64.
With its ability to prevent direct solar radiation the prismatic panels provide
good daylighting whilst maintaining good thermaL
comfort
and glare resistance for occupants
65.
Anidolic Openings
There
are three main types of anidolic openings:
·
The zenithal opening,
(the first illustration from left to right), can be attached to skylights to
provide homogeneous illumination and glare protection.
·
The integrated
system, (the second illustration from left to right), can be attached to
vertical windows to provide lightguiding into the depth of a room and
homogeneous illumination.
·
The Anidolic Ceiling,
(the third illustration from left to right), can be attached to a vertical
façade above a viewing window to provide lightguiding into the depth of a room
and homogeneous illumination.
66. Anidolic Openings
are effective in reducing the amount of artificial lighting in localised
rooms or areas, resulting in reduced
electrical loads.
67.
Reduction in amount of artificial lighting.
68. Anidolic Openings are products still in the testing
stage.
69. With anidolic openings still at the testing stage it is
uncertain whether they can provide adequate human comfort. It seems however, that they will offer
good daylighting to localised areas
whilst rejecting
heat gain.
70.
Louvres and Blinds
Louvres and blinds are shading
systems from direct sunlight and can be attached to vertical windows. The illustration above shows that louvres and
blinds prevent direct solar radiation from entering the building whilst
allowing a proportion of diffuse skylight into an area. Louvres and blinds are most effective in
providing glare protection.
71. Louvres
and blinds can be used in all climates.
72. Louvres
and blinds will reduce the need for artificial lighting. However, through heat absorption, from
direct sunlight through the blinds, it may increase the need for cooling.
73. Louvres
and blinds absorb some of the solar radiation and transmit the heat into the
area causing discomfort for occupants in a room.
Lightshelf
A lightshelf is used to redirect direct
sunlight into a room by attaching it to a window, as is shown in the above
diagram. The lightshelf can provide homogeneous illumination and lightguiding
into the depth of a room.
74. Lightshelfs
are most effective in temperate climates with cloudy skies.
75. Reduces
the need for artificial lighting in deep set rooms.
76. Provides a very effective source of daylighting.
77. Light
Guiding Glass
Light
guiding glass can be effective in all climates.
78. A special
consideration for light guiding glass is that it can reduce the need for
artificial lighting in deep-set
rooms.
79. Provides an effective
source of daylighting which can reduce the need for artificial lighting
and, hence, the electrical load.
80. N/A.
81. Timbers - Wood is a complex organic
polymer, when used as a building material it may need to be protected against
termites (subterranean), wood destroying fungi, marine borers, wood boring
insects, the weather and fire. This is especially true in hot and humid
climates, or whenever timber comes into contact with the ground or moisture.
For timber that is not naturally durable, a preservative treatment might be
considered to extend its service life. Treatment can be viewed as a means of
conserving a natural resource and extending the overall life expectancy of a
timber. However, preservative chemicals in treated timber are often perceived
to be hazardous to handle and to the environment. The use of treated timber can
be minimised through proper design, and species selection. Interior timber does
not need chemical treatment if appropriate termite barriers and dry conditions
are provided. It is possible to determine whether or not treated or untreated
timber is required. The decision must be based on professional judgement that
considers many factors, some of which are, the presence of a hazard (moisture,
insect, decay, chemical, etc); the degree of structural reliability required
(loadsharing or non-loadsharing, the cost of failure and if failure occurs the
potential for death or injury); the desired or expected service life of the
structure; the natural durability of the timber (resistance to decay or insect
attack); the type or design of the building or component; the presence of
sapwood (only sapwood can be effectively treated unless the timber is
mechanically incised). Many structures can be designed so that treatment is not
needed. This can be achieved by protecting the elements behind cladding that
can be replaced easily.
Hardwoods:
Mahogany/Oak: Tend only to be used for finishing’s, suitable for window
frames, doors, door frames, flooring in domestic and commercial environments,
High quality flooring finish and because of the subsequent expense and is
normally used in Museums, Concert Halls, Function Rooms, Castle and upmarket
residences and Hotels etc.
Softwoods:
Pine/Spruce: Suitable for commercial applications - roofs and trusses,
engineered multi storey projects, domestic applications - boundary and
retaining walls, decking and structural skeleton.
Bamboo: Suitable
for flooring, walls, roofs, exterior/siding, framings doors.
82. Installation is inexpensive.
83. No effect-electrically.
84. When the source of timber is close, and the
number of links in the supply chain are few, it is easier to directly assess the
environmental impacts and take responsibility of the use of the timber in
question; buyers are generally in a better position to influence the practices
of the supplier, less energy and resources are consumed in transport,
packaging, shipping and other processes. Bamboo is a fast growing grass that
can be harvested in three to five years. Cork is a natural flooring material
that is obtained from the outer bank of the cork oak tree that is regenerated
every 10 years and is therefore Carbon Neutral. Using rapidly renewable floor
substitutes reduces pressure on hardwood forests.
Hardwoods:
Mahogany/Oak: Available in UK.
Softwoods: Pine: Available
in UK.
Bamboo/Cork: Available
in countries such as China, USA and Australia, would then require to be
imported to the UK so would involve high amounts of embodied energy.
85. Materials
are Sound Absorbent.
86.
If required
materials can be treated to protect against condensation effects, see section
81.
87. Materials will
increase thermal comfort in the winter also in the summer if adequate
ventilation systems are installed.
88. Concrete- Suitable for use
in domestic and commercial buildings, can be used in walls, flooring; for
flooring applications use is especially appropriate in a commercial environment
where floors are required to support heavy structural loads such as plant.
89. Standard
building material, installation is inexpensive.
90. The materials
themselves have no effect on thermal comfort, if insulation is high quality
will increase thermal comfort
91 The water, sand and gravel
or crushed stone used in concrete production is abundant. A Typical residential
use concrete mix is in the proportions of Portland cement 12 per cent, sand 34
per cent crushed stone aggregate 48 per cent and water 6 per cent. With all
these raw materials, the distance and quality of the sources have a big impact
on transportation energy use, water use for washing.
As such a
large amount of embodied energy is used in the manufacture of concrete measures
may be incorporated elsewhere in building design in an attempt to reduce
embodied energy such as, using exposed concrete as a flooring material
consequently eliminating the need to use other flooring materials. In other
words using additional flooring materials may needlessly increase embodied
energy.
92. Concrete floors and walls can cause moisture problems,
particularly in humid and wetter climates and leads to mould and mildew growth
which can cause significant health problems. Good drainage around a structure,
the use of damp proofing or waterproofing, effective ventilation and the use of
insulation can alleviate these problems.
93. Little effect on aesthetic
comfort, no effect on lighting comfort, will improve thermal comfort provided
there is a good standard of ventilation, waterproofing and insulation.
94. Aerated Concrete floors and walls can cause moisture problems,
particularly in humid and Wetter climates, and lead to mould and mildew growth
which can cause significant health problems in certain individuals. Good
drainage around a structure, the use of damp proofing or waterproofing,
effective ventilation and the use of insulation can alleviate these problems.
95. Marginally more expensive than standard concrete.
96. The thermal properties inherent in Aerated Concrete can lead to
lower heating demands.
The thermal qualities of
Aerated Concrete.
Insulation quality can be improved using Aerated
Concrete blocks. Their inherent thermal qualities can provide an effective
barrier against the penetration of moisture and frost, the Figure 0.0.
Illustrates this. If used below the ground, Aerated Concrete blocks can reduce
heat loss by up to 25% compared to other forms of construction.
97. The water,
sand and gravel or crushed stone used in any concrete production is abundant. A
typical residential use concrete mix is in the proportions of Portland cement 12
per cent, sand 34 per cent, crushed stone aggregate 48 per cent and water 6 per
cent.
With all these raw materials, the distance and quality of the sources have a
big impact on transportation energy use, water use for washing. As such a
large amount of embodied energy is used in the manufacture of concrete measures
may be incorporated elsewhere in building design in an attempt to reduce
embodied energy such as, using exposed concrete as a flooring material
consequently eliminating the need to use other flooring materials. In other
words using additional flooring materials may needlessly increase embodied
energy.
98.
Lightweight concrete is commonly used for internal,
load-bearing walls where thermal and sound insulation are important.
considerations.
99. Use
of Aerated Concrete floors and walls can cause moisture problems, this is most common
in humid and wetter climates, and lead to mould and mildew growth which may
cause significant health problems in certain individuals. To alleviate these
problems good drainage around a structure, the use of damp proofing or
waterproofing, effective ventilation and the use of insulation is paramount.
100. No impact on visual
and aesthetic comfort, creates a good impact on thermal comfort with provision
of good ventilation system.
101. Metals-
Copper and Zinc can be used in electrical wiring, plumbing and heating applications,
Zinc can be used for guttering, Aluminium can be used for internal finishing’s,
roofing - If roof is pitched then Aluminium a suitable material to use, on a
flat roof a poly-membrane or asphalt covered roof is recommended.
102. Commonly used materials, installation is
inexpensive.
103. No
effect-electrically. Depending on the level of sunlight the material is going
to receive it may be coloured light or dark, the rule of thumb is when using in
hot countries it should be light to reflect the sun and dark in cooler
countries to absorb heat, this aids reducing heating loads.
104. The manufacturing processes involve large amounts of
embodied energy.
ALIMINIUM - Although Aluminium is relatively
easy to recycle and efficient recycling will permit the embodied energy in the
metal to be used again and again. Aluminium may well last the lifetime of the
building and may require smell levels of maintainance. It does not require
painting, or special treatments to prevent dry rot, fungus attack and rust.
Aluminium does not suffer from the effects of termite attack and therefore does
not require application of insecticides to the building or its surrounds.
The manufacture of aluminium involves
high-energy use, though this can be offset to some extent by utilising its
special characteristics to reduce the amount of metal used or to extend the
durability of structures or items it is to incorporate. The heat involved in
manufacture could also be conserved. Providing the design or construction
approach does not make it impossible to recover the material in a reasonably
unadulterated form, the potential for recycling aluminium is considerable.
Recycled aluminium requires about 5 per cent of the energy required to
manufacture primary metal and therefore recycling is a significant factor to be
considered in any life cycle approach to material selection.
The thermal energy required at
most stages of the production process and the large quantity of electrical
energy for electrolysis make aluminium one of the most energy intensive
materials. Over 125MJ of energy is required for each kilogram of primary
aluminium. The energy required to produce semi-fabricated aluminium products,
such as sheet or extrusions, is about 15 per cent that required producing the
primary metal ingots. Further processing, coating, fabrication and transport
results in a PER of 170 MJ/kg for aluminium building products.
ZINC - The raw materials used to manufacture lead
zinc include: lead and zinc ores, usually sulphides, coke, lead anode and
aluminium cathode materials for electrolytic zinc production.
Lead and zinc ores often occur
together and in association with metals such as copper and silver. The common
ores are sulphides and the production processes have some similarity to those
for copper, liberating SO2 and producing a concentrate for
subsequent production of the metal. Sulphuric acid is formed from the SO2
and is a useful by-product.
COPPER - The raw materials used to
manufacture copper include: copper ores, usually sulphides, froth flotation
reagents, siliceous fluxes, alloying metals such as tin, zinc and smaller
quantities of manganese and lead. Processes in the production of copper
include, copper ores are usually crushed, ground and concentrated at the mine
site by a froth flotation process. This stage is energy intensive and may
consume 100 MJ for each tonne of ore; concentrate, (containing 27-60 per cent
copper, 25-35 per cent sulphur, 25 per cent iron and 10 per cent water) is
transported to the smelter;
concentrate is mixed with
siliceous flux and roasted to about 650úC, liberating most of the sulphur as SO2;
and calcined material is mixed with additional siliceous flux and smelted in a
coal fired reverberatory or electric furnace to produce copper matte containing
about 45 per cent copper and slag. Flash furnaces combine the operations of
roasting and smelting and are more energy efficient but also liberate gases
with higher quantities of SO2. Depending on the technology employed,
the smelting state consumes 7-20 MJ/kg of copper (Biswas and Davenport 1980,
p.344).
Smelting involves the following
processes, slag from smelting is treated in an electric slag cleaning furnace
to recover the copper, or it is dumped; molten copper matte is converted to
blister copper (98.5-99.5 per cent pure) by mixing with siliceous flux and
scrap copper and blowing oxygen through the mix, liberating the remaining SO2;
fire refining at about 1100oC or electrolytic refining further purifies the
copper to 99.95-99.97 per cent pure (refining requires about 3 mj/kg of
copper); and fabrication of copper products.
105. If well insulated can
increase thermal comfort. No effect on aesthetic comfort though this is a
subjective view. When placing aluminium’s care should be taken they are not
badly placed which will routinely result in sunlight being reflected into
peoples eyes causing visual discomfort.
106. Poly-Membranes.
Generally used as a covering material on flat or pitched roofs. A Problem that
can occur in large flat commercial roofing applications such as a sports Hall
is that Large amounts of water may gather, which can be damaging to structural
strength of the roof, well-designed roofs should be specially designed to run
this water off.
107. Inexpensive.
108. No
effect-electrically. Colour of the material is important if the material is to
be used in a hot country it should be light coloured to reflect sunlight and
keep the building cool, in cooler countries it should be dark to absorb heat
which will aid in reducing heating loads.
109. The manufacturing
processes involve large amounts of embodied energy; the effects on
CO2 emissions
are highly negative due to the manufacturing processes.
110. The
chemical composition of the material if high quality protects against
condensation.
111.
If well insulated little or no effect on thermal comfort, no
effect on visual comfort, though is aesthetically acceptable, again a
subjective view.
112.
Cellulose
insulation is formed primarily from recycled paper products, such as used
newspapers. It can be applied to both
new buildings and retrofit projects as the material is applied by loose spray,
such that a jet gently fires it into place.
It is suitable for use in loft spaces as well as for wall insulation.
113.
Application
of cellulose insulation to retrofit wall applications would be difficult
without completely dismantling the wall for access. During its application the insulation causes a dust hazard but
mixing the material with some water prior to spraying can reduce this.
114.
The
installation cost is low as not only is the recycled material relatively cheap,
but the loose spray method of application is simple.
115.
Cellulose
insulation has very high insulative properties as it can be applied with
varying density. It can also greatly
reduce air leakage from the building envelope.
Consequently, the heat losses from a building and thus the heat demand
are greatly reduced.
116.
Cellulose
insulation has a very low embodied energy with the energy used in its
production quoted to be well over an order of magnitude less than for other
insulation materials. The material is
all recycled paper, which, once used, could again be recycled or allowed to
biodegrade. Resources of recyclable
paper are widely available so can be sourced locally to the project, minimising
the need to transport. There are no
CFCs or VOCs used in production thus eliminating emissions. However, the insulation material must be
treated with inorganic salts to protect against any fire hazard and also make
the material resistant to fungal attack.
These salts are boron salts, which are in limited supply and must be
mined. Additionally, the only mines of
boron are in the US and Turkey so the boron is transported over very long
distances.
117.
Cellulose
insulation is already commercially widely available, although not on the same
scale as fibreglass. Reliable
information on its performance is scarce, particularly for wall insulation.
118.
The
properties of insulation are such that sound is insulated against as well as
heat. The effectiveness of materials to
insulate against sound follows the same trend as their ability to insulate
against heat, such that cellulose has the greatest effect, followed closely by
fibreglass and then plastic foams. The
credentials of Air Krete are not well documented, but if it lives up to claims
then it should provide a high level of insulation towards sound. Transparent insulation, reportedly, also
performs well as an insulator to sound.
119.
Water
vapour in the air can be carried into insulation by air leakage through
walls. To prevent this problem air
leaks need to be sealed. This is often
done by applying a layer, which is impermeable to water, to the warm side of
the insulation, such as a polyethylene film or oil based paints.
120.
Insulation
improves the thermal comfort of a room, whilst helping to keep out unwanted
noise. Indoor air quality may be
negatively affected when air passage is prevented to too great an extent. A good ventilation system would of course
solve this problem. The limited amount
of research has not shown there to be any harmful gaseous releases, even from
the fire retardants.
121.
Fibreglass
is the most common type of loose fill insulation used. It is supplied in blanket form and is rolled
out into place. Consequently,
fibreglass can be used in lofts and walls and for both new build and retrofit
applications.
122.
Fibreglass
is widely available and the cheapest insulation material, both to buy and
install. .
123.
Insulation
properties are high, although quoted as lower than cellulose. However, heat demands will be significantly
reduced.
124.
The
embodied energy of fibreglass is quoted as being an order of magnitude greater
than that of cellulose. It is produced
from molten glass, which is spun into long fibres and bound together. This is quite an energy intensive
process. Fibreglass insulation can
include a proportion of recycled glass.
No CFCs are used during manufacture.
Resources are widespread so can be sourced near to the project location,
minimising the transportation required.
125.
Fibreglass
is seen as a standard insulation material with no known defects, thus
uncertainties associated with its use are minimal
126.
It
has been suggested that fibres that may be released from fibreglass are
carcinogenic, although research is conflicting, as some research states that
indoor air quality is not significantly affected by the fibres. The thermal comfort of building occupants
will of course benefit.
127.
Plastic
foams such as polystyrene, polyurethane and polyisocyanurate are widely used as
insulation materials. The insulation is
in the form of a blanket which can be laid out in loft spaces or installed in
walls.
128.
Plastic
foams are a widely available and reasonably cheap material, both to buy and
install. Having been on the market for
a long period of time, the price of this insulation compares favourably with
other types available.
129.
Plastic
foams have an embodied energy that is greater than cellulose by an order of
magnitude and higher than that of fibreglass also. Plastic foams are produced from valuable fossil fuel resources
and large amounts of energy are required in processing. The recycled content varies between foam
types but is never a significant percentage.
The location of material source should also be as close as possible to
minimise transportation. CFCs have been
used in manufacture up until recently.
130.
VOCs
are released from the plastic foams during their use affecting the indoor air
quality of a building.
131.
Air
Krete is an inorganic foam of magnesium oxide, which is derived from
seawater. Air Krete is foamed in place
behind the wall. The material is lightweight
but rigid and friable.
132.
Since
it is relatively new to the market, the cost of Air Krete is quite high.
133.
Insulative
properties of Air Krete are quoted to be very high, thus heat demands should be
significantly reduced but there is a lack of information to back up claims.
134.
The
embodied energy is lower than that for plastic foams but still higher than for
cellulose. No CFCs are used and VOC
emissions are low. The material comes
from the readily available source that is seawater.
135.
Information
on its recommended use and properties is not readily available, thus
uncertainties associated with its use are high.
136.
Transparent
Insulation differs from other insulation materials in that it must prevent the
passage of heat whilst still allowing solar energy to pass through. Applications include the insulation of solar
collectors, use in Trombe walls and as a form of advanced glazing.
137.
Installation
costs are relatively high, mainly due to the complex applications of
transparent insulation, but also because the technology is still relatively
new.
138.
The
use of transparent insulation, for example, in Trombe walls reduces heating
loads. Solar radiation, that is short
wavelength radiation, is able to pass through the insulation, whilst long
wavelength radiation is reflected back into a room.
139.
Transparent
insulation is made from plastics.
Consequently it uses valuable fossil fuel resources and the amount of
energy required in processing is high.
It would be possible to include some recycled plastics. Again the location of such material has a
significant impact on the embodied energy.
140.
The
applications of transparent insulation are relatively new, thus not used widely
on a commercial scale. Although there
is some theoretical information on transparent insulation, its practical
application is neither proven nor well documented.
141.
Transparent
insulation releases heat into a room and prevents its escape, keeping
temperatures steady, thus the thermal comfort is improved. Visually it is useful as its insulative
properties can be utilised while still allowing natural light to enter a room,
to the benefit of visual comfort.
Trombe
Wall 
142.
Trombe
walls are a form of solar heating, forming part of the building facade. Sunlight is absorbed by an external dark surface
and stored in the thermal mass of the wall.
Several variations are available, fitted with insulation, different
absorbing materials and storage materials with a larger heat capacity, such as
water.
143.
Trombe
walls are often difficult to implement in design as they conflict with building
requirements for view and access. The
wall should be south facing to gain the most sunlight but shading devices are
fitted to prevent overheating in summer.
Even with these shading devices, heat gain is difficult to control,
resulting in instances of overheating.
The construction of Trombe walls is such that high levels of maintenance
are required. Mechanical failure is a
persistent problem
144.
Installation
costs are high in comparison to that of standard structures. Trombe walls do not have a standard
construction procedure.
145.
The
use of trombe walls for heating in winter and cooling in summer will have a
marked effect on the electrical and heating requirements of a building. The heat from solar radiation is stored in
the wall for long periods and transmitted to the room several hours later, i.e.
at night. In summer, the wall can be
used to draw cool air through the room and in the winter, it provides space
heating.
146.
A
trombe wall uses a large number of materials, such as glazing and plastics,
which have a high-embodied energy. An
analysis of energy payback time would be required to justify their use. Materials which can be sourced locally would
be a better choice.
147.
Trombe
walls are not widely used commercially.
The theory behind them is well established, however, there are few
documented practical examples to verify its effectiveness.
148.
Thermal
comfort of occupants will be improved and air circulation will be improved.
149.
Breathable
walls allow high moisture permeability.
Thus higher amounts of moisture are able to migrate from the inside
structure to the outside structure.
There is no moisture barrier, such as the polyethylene film, which is
applied with standard insulation.
150.
The
materials used in a breathable wall are carefully selected to provide the
correct resistance to vapour flow thus enabling moisture to diffuse naturally
through the material. The inside
sheathing of the insulation material must have a greater resistance to flow
than the outside material so that moisture flows outwards and not inwards.
151.
Installation
costs are comparable with standard walls as the structure is fairly similar.
152.
Good
insulation properties will reduce heating duties. Greater airflow through the wall than that for standard structures
will remove heat from the building such that heating loads are not reduced to
quite the same extent.
153.
Breathing
walls often use cellulose insulation, thus the embodied energy can be lower
than for standard walls. (See section 116)
154.
Moisture
is allowed to pass through the wall in a regulated manner, so condensation
should not be a problem.
155.
As
with all insulation, the thermal comfort of occupants should be enhanced. Additionally, indoor air quality is enhanced
by the high level of diffusion of vapour and air through the wall.
156.
Phase
Change Materials with a melting point slightly above room temperature are used
in construction. They can be
incorporated into both interior and exterior walls, coupled with other
insulating materials or even combined with under-floor heating.
157.
PCMs
are also undergoing investigation into their use as a high-density storage
medium for energy gained, for example, from solar collectors. As with water storage tanks, adequate space
must be provided in which to situate the tank.
The inclusion of phase change materials within walls must be considered
from the outset so that safe loads upon the wall can be determined.
158. PCMs are only produced by a handful of companies and are still
undergoing a great deal of research.
Consequently, their cost is still high.
159.
PCMs
absorb and release heat as the temperature of the room rises and falls and thus
reduce fluctuations in room temperature and consequently reduce heating and
cooling loads. During warm hours of the
day, a PCM with the correct melting temperature will melt thus removing heat
from a room. This heat remains stored
in the material until the temperature of the room cools, upon which time the
PCM solidifies releasing heat back to the room. Here we can see that PCMs can be used to keep the temperature of
a room reasonably constant. Electrical
demands for daytime cooling will be reduced as will heating demands. PCMs combined with under floor heating are
used to release heat to a room steadily thus controlling both the temperature
of the room and reducing the amount of heating required. Hydrated salt PCMs have a higher energy
storage density than paraffins thus have a greater impact on heating and
electrical demands.
160.
Paraffins
have a higher embodied energy than hydrated salts. They are also produced from valuable fossil fuel resources. Both materials will involve high amounts of
energy in transportation as their manufacture is not widespread.
161.
The stability of PCMs is still variable and the benefits of
using either hydrated salts or paraffins and is still in debate. Consequently, there is still a high level of
uncertainty involved in the use of PCMs.
162.
The
temperature of a building can be kept at a more constant temperature thus
improving the thermal comfort of occupants.
Research has not shown any gaseous releases from phase change materials,
thus indoor air quality should not be affected. However, it should be remembered that paraffin PCMs are both
toxic and flammable, whilst hydrated salts are not.
163.
Low
emissivity glazing is applied where maximum lighting is desired but a greater
control over thermal gains is required, such that short-wavelength radiation
(visible light) passes through the glazing but longer wavelength (heat)
radiation is reflected back into the room or prevented from entering, depending
on requirements.
164.
Glazing
has a huge effect on the thermal gains and electrical demands of a
building. Particularly in modern
design, large areas of building facades are comprised of glazing for aesthetics
reasons. Glazing affects the light
available to the interior. This is
important when considering the use of daylighting. Orientation of glazed facades will affect their impact, that is
southerly facing facades will receive high amounts of solar radiation compared
with other orientations. The presence
of other buildings in the vicinity may affect the optimum use and placing of
glazing.
Of course, the more complex the
glazing, the greater its effect on building performance. Increasing the level of glazing to triple glazing
will restrict the passage of long and short wave radiation through it. The addition of a low-e coating will, in
particular, restrict heat gains and losses, as will an inert gas. The optimum solution may be to install
dynamic glazing hence enabling levels of lighting and heat gain/loss to be
adjusted to a user's need at a given time.
The choice of glazing depends very
much on the siting and in particular the orientation of the glazing. The choice
of frame must also be carefully considered in order to avoid thermal bridging.
165.
Installation
costs for conventional glazing are now becoming standard, and lowering as
competition between companies increases.
Triple glazing is often available from standard glazing companies but an
increase in cost reflects the increased complexity. Low-e coatings and gas-filled glazings are not widely
commercially available and thus costs immediately increase. Very often, it is not the material that is
expensive, rather from where it is sourced and its sophisticated installation. As a guide, the cost of low-e glazing is
estimated to be around 10-15% higher than that of conventional glazing with
costs increasing further with greater glazing complexity.
166.
As
already mentioned, the use of glazing can have enormous effects, both positive
and negative, on heating and electrical demands for a building. To begin with the negative problems; solar
radiation transmitted to a room will increase room temperature and increase the
need for cooling and as such increase electrical demands. Applying shading to these windows would
lower cooling duties but increase electrical demands for artificial
lighting. Standard glazing presents
these problems, however, as already stated advanced glazings begin to solve
these problems. Low-e glazings will of
course reduce solar gains to a room whilst still allowing light to enter. Consequently, cooling loads are reduced and
the windows can be used as sources of daylighting. Gas-filled glazing will provide a decrease in thermal losses or
gains to a building by reducing conduction through the glazing, thus heating
demands will be reduced in winter and cooling demands reduced in summer. Dynamic glazing, once again, would be ideal
as it can vary according to the outside conditions, thus reducing heating, cooling
and electrical demands at otherwise peak times.
167.
The
manufacture of glazing has an inherently high embodied energy. However, the amount of embodied energy will
increase depending on the complexity of the technology. The lowest embodied energy is found in
single glazing with wooden frames. The
embodied energy increases with the number of panes of glass along with the
choice of frame. The manufacture of
plastic and metal frames uses much greater quantities of energy than wooden
frames. Specialised glazings give rise
to a huge leap in embodied energy, as the processes to produce, for example,
low-e coatings are very energy intensive.
Specialised glazings are often transported over larger distances as
their manufacture is not widespread.
This will once again lead to increased embodied energy.
From a first look it would seem
sensible to use to simplest glazing possible in order to reduce embodied
energy. However, to compare the
glazings fairly, energy payback time must also be taken into consideration. The amount of energy saved by increasing the
level of glazing from single to double-glazing produces a very short energy
payback time. This energy payback time begins to increase somewhat as low-e
coatings are added, however they are still within reasonable levels. It is when we reach very complex glazing
strategies, in particular dynamic glazing, that energy payback times become
longer than the lifetime of the glazing, according to literature. It is then that the question must be asked
whether minimum energy use during the use phase out ways the vast amounts of
energy involved in manufacture.
168. Obviously, the use of more sophisticated
glazing increases the risk posed by the project. Dynamic glazings, also feasible in principle, are far from commercial
use. Their cost and the risk involved,
in technology more prone to problems, limits their use to demonstration
projects at present.
169. It is well known that increased glazing
will provide insulation against sound as well as heat. The greater the number of panes, the better
the insulation, thus triple glazing is better than double glazing. Use of inert gases, as in gas filled
glazing, will also result in a reduction in the transmission of sound across the
glazing compared with air-filled glazing, whilst low-e coatings will not have
any marked effect.
170. The use of advanced glazings can
dramatically increase human comfort within a building. Thermal comfort will be increased by reduced
heat gains and losses; visual comfort will be increased by greater use of
daylighting and reduced glare. Dynamic
glazing would have the greatest impact as glazing can respond to changes in
climate and also changes in user demand, in the case of active systems.
171. Gas-filled glazings are suitable in
applications where a decrease in heat losses from a building is of great
importance, for example in colder climates, where solar gains are not a
problem, if not desirable.
172. Triple glazing offers increased levels of
thermal insulation in comparison to standard double glazing and would be
applicable in colder climates where a tight building envelope with minimum heat
and air losses are desirable. Low-e
coatings and inert gases can be applied to triple glazing to improve its
properties.
173. Dynamic glazing is seen as a versatile
glazing for the future. Active glazing
enables building occupants to have total control over their environment and
passive glazing can adapt to the surroundings it is presented with. Consequently, these glazings could be
applicable to any situation.
174 Plasterboard is used for internal,
non-load-bearing walls, as well as for cladding of load-bearing walls.
175 Plasterboard is a standard building
material, used in most construction processes, thus costs are relatively low
and dependent on competition between companies.
176 Plasterboard cladding adds to the
insulation of external walls thus lowering heat demands. Partitioning with plasterboard also gives
smaller areas for space heating.
177. Plasterboard is produced from gypsum with
its production giving a moderate embodied energy. The gypsum may be mined, which is very energy intensive, or taken
as the by-product from chemical manufacturing, such as hydrogen fluoride
manufacture. This use of a by-product
would be less energy intensive as otherwise wasted materials are utilised, but
the gypsum would require purification, which requires energy. Before gypsum can be used as Plaster of
Paris in plasterboard manufacture, water must be driven off, once again
requiring the input of energy. Never
the less, the embodied energy of plasterboard is seen as being lower than for
bricks even when the use of insulation increases embodied energy levels.
178. Plasterboard is not well known for
insulating against sound, as is shown in many modern buildings. This could be improved by the addition of an
insulating material.
179. The main benefit to human comfort to be
had from plasterboard is increased thermal comfort from added insulation to
external walls. There is no known
release of toxins from the materials which could affect indoor air quality.
180. Bricks are the most widely used building
material, as they are versatile and can be built to withstand variable loads.
181. Bricks are available in a wide range of
sizes, shapes and colours to blend with surrounding buildings and
features. They combine well with other
building materials used in construction.
182. Bricks are a commonly used and reliable
building material, thus costs are low and vary due to competition between
suppliers.
183. Bricks have reasonably good insulation
properties due to air trapped inside.
Used in well constructed cavity walls, bricks help to provide a tight
building envelope so that heat demands are minimised.
184. The manufacture of bricks is an energy
intensive process, which involves the extraction of the clay and vast amounts
of energy to fire the kilns.
Additionally, bricks are transported in vast quantities over sometimes
large distances. The embodied energy of
bricks, together with their environmental impact is of concern, thus measures
have been taken to reduce these. The
extraction of clay is attempted in a sensitive manner so as not to have as high
an impact on the landscape. Kilns used
for brick firing are being developed to improve their efficiency. The recycling of bricks is being promoted
and brick deliveries are being synchronised to reduce the number of journeys
made by lorries.
185. Bricks provide a reasonable amount of
insulation against sound and, coupled with insulation materials, provide good acoustic
properties.
186. If the temperature of the bricks drops to
the dew point of water, the water will condense thus creating a moisture
problem within the wall. This can be
prevented by good quality wall construction, in which the internal face of the
wall insulation is protected by a moisture barrier, such a polyethylene film,
and the internal temperature of the wall is maintained above the moisture dew
point. For breathing walls, good
airflow through the wall should prevent condensation.
187. Bricks,
and more specifically, the structure of external walls will affect the thermal
comfort and indoor air quality of a building.
A highly insulated wall will of course aid in maintaining the
temperature of a building. The level to
which the building is air tight will affect the indoor air quality of the
building. Adequate ventilation must be designed for cases of a tightly sealed
envelope. Visually, bricks can be an
attractive external or internal feature.
188. Adobe Bricks are capable of withstanding heavy
loads, when thick walls are constructed, thus can be used in load bearing and
non-load bearing applications. Their
strength is not as great as that of conventional bricks, but their use is still
possible with steel and timber frames in building structures several stories
high.
189. The appearance of the Adobe bricks will
reflect their source as colours of clay and sand vary a great deal with
location. The use of the bricks in
their native area will produce buildings that blend well with the surroundings.
190.
The
cost of the Adobe bricks is relatively low but affected by intensity of labour
required in their production. Some
production on a commercial scale has lead to expensive products for this very
reason.
191. Adobe bricks have a high thermal mass but
are not great insulators as not much air is trapped in the structure. When required, linings can be applied to
increase levels of insulation. In the
warm climates where use of Adobe bricks is common, insulation is perhaps not of
great importance and the mud bricks actually help to keep a building cool, thus
lowering electrical demands for cooling.
192.
Clay
and sand used in producing Adobe bricks is sourced locally and of course the
energy used to dry the bricks comes directly from the sun so embodied energy is
low. The use of fossil fuels is
minimal, although large amounts of water are needed.
193. Although the use of Adobe bricks is not
widespread, it is now established, particularly in warmer climates. Consequently their performance has been
proven so uncertainties are low.
194. Adobe bricks have very high sound
insulation properties.
195. Adobe bricks require protection from
moisture, particularly from extreme weather conditions. The structural properties of otherwise
sturdy bricks can be affected by weathering or seepage of water.
196. Adobe bricks are essentially breathable
walls such that indoor air quality should be high. In some cases additional ingredients are added to the bricks to
protect them, such as bitumen. This can
cause emissions of hydrocarbons, which will of course have a negative effect on
the air quality. Although not good
insulators, the bricks provide good thermal comfort by keeping buildings cool
in warm climates.
RENEWABLE TECHNOLOGY SELECTION TOOL
PROBLEMS DEVELOPING THE HIGH LEVEL TOOL
