Passive Solar HousingPassive solar systems are self-sufficient
buildings which rely on naturalprinciples insted of mechanical
systems to provide a non-pollutingsource of heating and
cooling.IntroductionPassive energy is more sustainable than active
energy systems because passivesystems use far fewer natural
resources to build and maintain. They do not rely soheavily upon
gas for heating or coolants for air conditioning. Passive systems
aredesigned so that they can take natural energy from the sun to
heat a building anduse specific design principles to cool a
building. Passive energy systems are also cheaper thanactive
systems because they are less susceptible to malfunction since they
rely completelyupon nature, rather than using mechanical equipment
to produce energy. In orderto create a home that will maximize the
effects of passive solar heating, a designermust take many
different variables into account. Two major ideas crucial to
creatingeffective passive solar housing are orientation and
materials. Passive solar buildingsshould be oriented to receive as
much southern sun as possible. In the summer,the hot sun can be
blocked by using overhangs or through landscaping like
largefoliated trees. In the winter, sun should help heat the house
because the sun angleis lower in the sky allowing more sun to hit
the glazing more directly. Thoughtshould also be given to the
specifications of the windows for maximum solar gainsand heat loss.
By using the right building materials such as masonry or concrete
andcombining them with effective insulation, solar energy can be
contained in thehouse allowing it to be comfortable year
round(Desbarats 1980, 232).Building OrientationBuilding orientation
is crucial to maximizing energy production in a passive solarhome.
Because passive solar homes rely on natural sunlight to power the
building'sutilities, the building should be oriented on the site in
a way that will allow it tomaximize the amount of sunlight. The
best way to achieve this is to orient the houseon the east-west
axis and concentrate most of the house's glazing on the southwall.
This allows the home to receive the most direct sunlight for the
longest periodof time(Hibshman 1983, 261). Heat travels through
windows very easily, however heatdoes not exit as easily. Once the
heat passes through the window, it breaks up and ittakes much
longer for that heat to exit(Button 1993, 129). This allows heat
that enters abuilding to stay in the building for a long time. This
is a helpful principal for heatinga building in the winter and is
the reason why windows should receive as much lightas possible in
the winter. However, in the summer, the hot sun can become
anuncomfortable problem. To alleviate some of this heat, passive
solar homes shouldbe designed with attic fans or some sort of
operable clerestory windows which canbe opened to release some of
the hot air when it rises. Glazing should be greatlyreduced on the
east and west walls and should be virtually eliminated on the
northside of the home because most cold winds in winter come from
the north andwest(Desbarats 1980, 56). Because the house needs as
much protection from thesewinds as possible, and glazing cannot
provide this protection, windows should beeliminated.(Desbarats
1980, 28).Glass The amount as well as type of glass windows used in
a house are very importantconsiderations in terms of thermal
comfort, cost and efficiency. There are manydifferent types of
windows available: single, double and triple paned(Button 1993,
164)A single pane is simply one pane of glass. These are generally
the worst types of windowsto use. Although they are the cheapest
windows available, they are not energy efficientand they allow more
heat gain in summer and heat loss in winter than either the
doubleor triple paned windows do. Double pane windows are much more
energy efficient.The reason is the cold winter air passes through
the first pane but then must passthrough a gap of either air or
Argon gas before it reaches the second pane. The reasonthis is
helpful is because air or Argon gas provide excellent insulation
and do not allowthe cold to penetrate nearly as much as it would if
there were only one pane. Triplepaned windows work on the same
principal as double paned but they are even moreenergy efficient
because there is even an additional layer of insulation(Button
1993, 166). It isalso possible to get windows with coatings such as
low emissivity coatings (low-E)which help to block the suns harmful
rays but still allow visible light to pass through(Button 1993,
173).(Hibshman 1983, 29) R-Values for Different Types of
GlassThermal Mass Thermal mass is another important concept to keep
in mind when dealing with energyefficient housing. It is important
for these types of homes to be built with materialsthat have a
large amount of thermal mass(Hibshman, 1983, p.48). Such materials
are brick,stone and concrete. These materials are ideal because
materials with a large thermal massabsorb much of the energy they
receive from the sun. These materials absorb and release
energycompletely, but slowly. Because it takes a long time for the
energy to be releasedafter it is absorbed, a phenomenon known as
lag, warm sunlight that is absorbedduring the day is finally
released over time at night. This is another natural
phenomenonwhich proves helpful because it provides warmth at night
when the house is the coldest andheat is necessary. Because all of
the heat is released at night the floor is then cool for thenext
day and consequently this helps to cool the rest of the house. It
is also important leavethe concrete floors on the south side of the
house exposed. If they are carpeted, they lose mostall of their
thermal mass properties. However, carpeting would be acceptable on
thenorth side of the house because there should be almost no
windows there anyway(Hibshman, 1983, p.32).(Hibshman, 1983, p.32)
How Thermal Mass WorksAffordability in Sustainability Using Passive
Solar HeatingCost is a very important factor for designing
sustainable architecture. Aside from creatingenviornmentally
friendly architecture, sustainable architecture allows lower
building andmaintenance costs. Affordability goes hand in hand with
sustainablity and is something whichwe, as designers, should
concentrate on when designing the housing in East St. Louis. One
wayto create affordable homes is by using everyday, affordable
materials to replace expensive andwasteful mechanical ones. One way
this can be achieved is by using 55-gallon drums filled withwater
to create thermal mass, a very necessary element for passive solar
heating. By placing thesedrums in direct sunlight, they will absorb
the sun's energy and, because lag also occurs in water,they will
have the same effect on the house that materials like concrete or
masonry would, butwithout the cost(Hibshman, 1983, p.50). Another,
affordable solution is to use these drumsfilled with water to
replace water heaters. They can be placed in the roof or any other
placewhere they will receive a lot of direct sunlight (see figure
on "Sustainable Design" page).The owner can then use that water
which has been naturally heated for bathing or cooking,replacing a
mechanical hot water heater and greatly reducing cost(Hibshman,
1983, p.53).Another way to create affordable yet sustainable
architecture is by using unconventionalbuilding techniques. One way
is to use post-and-beam units instead of conventional stickframing.
The posts are then anchored into the concrete. This creates a very
stable framingsystem and also reduces costs because no 2"x4" studs
are used and therefore, less wood isused. However, the most
important money saving factor in this construction is the use
ofprefabricated wall systems. These systems are cut into 4'x8'
sheets and can thenbe placed right in between the posts on the
construction site with no wated materials used(Hibshman, 1983,
p.71). This is also a faster method of construction so the labor
costswill also be reduced. While these are just a few ideas more
specific examples using thesetechniques can be found in the sited
material.Diagram showing good passive solar design(Hibshman, 1983,
p.71)Previous -Next
Passive solar building designFrom Wikipedia, the free
encyclopedia
Elements of passive solar design, shown in a direct gain
application
Activeand passive solar systems are used in theSolar Umbrella
houseto achieve nearly 100%energy neutrality.Inpassive solar
building design, windows, walls, and floors are made to collect,
store, and distributesolar energyin the form of heat in the winter
and reject solar heat in the summer. This is called passive solar
design or climatic design because, unlike activesolar
heatingsystems, it doesn't involve the use of mechanical and
electrical devices.[1]The key to designing a passive solar building
is to best take advantage of the localclimate. Elements to be
considered include window placement and glazing type,thermal
insulation,thermal mass, and shading. Passive solar design
techniques can be applied most easily to new buildings, but
existing buildings can be adapted or "retrofitted".Contents[hide]
1Passive energy gain 2As a science 3The solar path in passive
design 4Passive solar thermodynamic principles 4.1Convective heat
transfer 4.2Radiative heat transfer 5Site specific considerations
during design 6Design elements for residential buildings in
temperate climates 7Efficiency and economics of passive solar
heating 8Key passive solar building design concepts 8.1Direct solar
gain 8.2Indirect solar gain 8.3Isolated solar gain 8.4Heat storage
8.5Insulation 8.6Special glazing systems and window coverings
8.7Glazing selection 8.7.1Equator-facing glass 8.7.2Roof-angle
glass / Skylights 8.7.3Angle of incident radiation 8.8Operable
shading and insulation devices 8.9Exterior colors reflecting -
absorbing 9Landscaping and gardens 10Other passive solar principles
10.1Passive solar lighting 10.1.1Interior reflecting 10.2Passive
solar water heating 11Comparison to the Passive House standard in
Europe 12Design tools 13Levels of application 13.1Pragmatic
13.2Annualised 13.3Minimum machinery 13.4Zero Energy Building 14See
also 15References 16External linksPassive energy gain[edit]Passive
solartechnologies usesunlightwithout active mechanical systems (as
contrasted toactive solar). Such technologies convert sunlight into
usable heat (water, air, thermal mass), cause air-movement
forventilating, or future use, with little use of other energy
sources. A common example is asolariumon theequator-side of a
building.Passive coolingis the use of the same design principles to
reduce summer cooling requirements.Some passive systems use a small
amount of conventional energy to control dampers, shutters, night
insulation, and other devices that enhance solar energy collection,
storage, and use, and reduce undesirableheat transfer.Passive solar
technologies include direct and indirectsolar gainfor space
heating,solar water heatingsystems based on thethermosiphonorgeyser
pump, use ofthermal massandphase-change materialsfor slowing indoor
air temperature swings,solar cookers, thesolar chimneyfor enhancing
natural ventilation, andearth sheltering.More widely, passive solar
technologies include thesolar furnaceandsolar forge, but these
typically require some external energy for aligning their
concentrating mirrors or receivers, and historically have not
proven to be practical or cost effective for widespread use.
'Low-grade' energy needs, such as space and water heating, have
proven, over time, to be better applications for passive use of
solar energy.As a science[edit]Thescientificbasis forPassive Solar
Building Design[2]has been developed from a combination
ofclimatology,thermodynamics( particularlyheat transfer:conduction
(heat),convection, andelectromagnetic radiation),fluid
mechanics/natural convection(passive movement of air and water
without the use of electricity, fans or pumps), and humanthermal
comfortbased onheat index,psychrometricsandenthalpycontrol for
buildings to be inhabited by humans or animals,sunrooms, solariums,
andgreenhousesfor raising plants.Specific attention is divided
into: the site, location and solar orientation of the building,
localsun path, the prevailing level ofinsolation(latitude/ sunshine
/ clouds /precipitation (meteorology)), design and construction
quality / materials, placement / size / type of windows and walls,
and incorporation of solar-energy-storingthermal masswithheat
capacity.While these considerations may be directed toward any
building, achieving an ideal optimized cost / performance solution
requires careful,holistic,system integrationengineeringof these
scientific principles.Modern refinementsthrough computer modeling
(such as the comprehensive U.S. Department of Energy "Energy
Plus"[3]energy simulation software), and application of decades of
lessons learned (since the 1970s energy crisis) can achieve
significant energy savings and reduction of environmental damage,
without sacrificing functionality or aesthetics.[4]In fact,
passive-solar design features such as a greenhouse / sunroom /
solarium can greatly enhance the livability, daylight, views, and
value of a home, at a low cost per unit of space.Much has been
learned about passive solar building design since the 1970s energy
crisis. Many unscientific, intuition-based expensive construction
experiments have attempted and failed to achievezero energy- the
total elimination of heating-and-cooling energy bills.Passive solar
building construction may not be difficult or expensive (using
off-the-shelf existing materials and technology), but the
scientific passive solar building design is a non-trivial
engineering effort that requires significant study of previous
counter-intuitive lessons learned, and time to enter, evaluate, and
iteratively refine the computer simulation input and output.One of
the most useful post-construction evaluation tools has been the use
ofthermographyusing digitalthermal imaging camerasfor a formal
quantitative scientificenergy audit. Thermal imaging can be used to
document areas of poor thermal performance such as the negative
thermal impact of roof-angled glass or a skylight on a cold winter
night or hot summer day.The scientific lessons learned over the
last three decades have been captured in sophisticated
comprehensive energy simulation computer software systems (like
U.S. DOE Energy Plus,et al.).Scientific passive solar building
design with quantitativecost benefitproduct optimizationis not easy
for a novice. The level of complexity has resulted in ongoing
bad-architecture, and many intuition-based, unscientific
construction experiments that disappoint their designers and waste
a significant portion of their construction budget on inappropriate
ideas.The economic motivation for scientific design and engineering
is significant. If it had been applied comprehensively to new
building construction beginning in 1980 (based on 1970's lessons
learned), America could be saving over $250,000,000 per year on
expensive energy and related pollution today.[citation needed]Since
1979, Passive Solar Building Design has been a critical element of
achievingzero energyby educational institution experiments, and
governments around the world, including the U.S. Department of
Energy, and the energy research scientists that they have supported
for decades. Thecost effectiveproof of conceptwas established
decades ago, butcultural assimilationinto architecture,
construction trades, and building-ownerdecision makinghas been very
slow and difficult to change.[citation needed]The new terms
"Architectural Science" and "Architectural Technology" are being
added to some schools of Architecture, with a future goal of
teaching the above scientific and energy-engineering
principles.[citation needed]The solar path in passive
design[edit]
Solar altitude over a year; latitude based onNew York,New
YorkMain articles:Sun pathandPosition of the SunThe ability to
achieve these goals simultaneously is fundamentally dependent on
the seasonal variations in the sun's path throughout the day.This
occurs as a result of theinclinationof the Earth's axis of rotation
in relation to itsorbit. Thesun pathis unique for any given
latitude.In Northern Hemisphere non-tropical latitudes farther than
23.5 degrees from the equator: The sun will reach itshighest
pointtoward the South in the Northern Hemisphere and the North in
the Southern Hemisphere (in the direction of the equator) As
wintersolsticeapproaches, theangleat which the
sunrisesandsetsprogressively moves further toward the South and the
daylight hours will become shorter The opposite is noted in summer
where the sun will rise and set further toward the North and the
daylight hours will lengthen[5]The converse is observed in the
Southern Hemisphere, but the sun rises to the east and sets toward
the west regardless of which hemisphere you are in.In equatorial
regions at less than 23.5 degrees, the position of the sun atsolar
noonwill oscillate from north to south and back again during the
year.[6]In regions closer than 23.5 degrees from either
north-or-south pole, during summer the sun will trace a complete
circle in the sky without setting whilst it will never appear above
the horizon six months later, during the height of winter.[7]The
47-degree difference in the altitude of the sun atsolar noonbetween
winter and summer forms the basis of passive solar design. This
information is combined with local climatic data (degree day)
heating and cooling requirements to determine at what time of the
year solar gain will be beneficial forthermal comfort, and when it
should be blocked with shading. By strategic placement of items
such as glazing and shading devices, the percent of solar gain
entering a building can be controlled throughout the
year.Onepassive solarsun path design problem is that although the
sun is in the same relative position six weeks before, and six
weeks after, the solstice, due to "thermal lag" from thethermal
massof the Earth, the temperature and solar gain requirements are
quite different before and after the summer or winter solstice.
Movable shutters, shades, shade screens, or window quilts can
accommodate day-to-day and hour-to-hour solar gain and insulation
requirements.Careful arrangement of rooms completes the passive
solar design. A common recommendation for residential dwellings is
to place living areas facing solar noon and sleeping quarters on
the opposite side.[8]Aheliodonis a traditional movable light device
used by architects and designers to help model sun path effects. In
modern times, 3D computer graphics can visually simulate this data,
and calculate performance predictions.[4]Passive solar
thermodynamic principles[edit]Personalthermal comfortis a function
of personal health factors (medical, psychological, sociological
and situational), ambient air temperature,mean radiant temperature,
air movement (wind chill,turbulence) andrelative humidity(affecting
humanevaporativecooling).Heat transferin buildings occurs
throughconvection,conduction, andthermal radiationthrough roof,
walls, floor and windows.[9]Convective heat
transfer[edit]Convective heat transfercan be beneficial or
detrimental. Uncontrolled air infiltration from poorweatherization/
weatherstripping / draft-proofing can contribute up to 40% of heat
loss during winter;[10]however, strategic placement of operable
windows or vents can enhance convection, cross-ventilation, and
summer cooling when the outside air is of a comfortable temperature
andrelative humidity.[11]Filteredenergy recovery ventilationsystems
may be useful to eliminate undesirable humidity, dust, pollen, and
microorganisms in unfiltered ventilation air.Natural convection
causingrisingwarm air and falling cooler air can result in an
uneven stratification of heat. This may cause uncomfortable
variations in temperature in the upper and lower conditioned space,
serve as a method of venting hot air, or be designed in as a
natural-convection air-flow loop forpassive solarheat distribution
and temperature equalization. Natural human cooling
byperspirationandevaporationmay be facilitated through natural or
forced convective air movement by fans, but ceiling fans can
disturb the stratified insulating air layers at the top of a room,
and accelerate heat transfer from a hot attic, or through nearby
windows. In addition, highrelative humidityinhibits evaporative
cooling by humans.Radiative heat transfer[edit]The main source
ofheat transferisradiant energy, and the primary source is the sun.
Solar radiation occurs predominantly through the roof and windows
(but also through walls).Thermal radiationmoves from a warmer
surface to a cooler one. Roofs receive the majority of the solar
radiation delivered to a house. Acool roof, orgreen roofin addition
to aradiant barriercan help prevent your attic from becoming hotter
than the peak summer outdoor air
temperature[12](seealbedo,absorptivity,emissivity,
andreflectivity).Windows are a ready and predictable site
forthermal radiation.[13]Energy from radiation can move into a
window in the day time, and out of the same window at night.
Radiation usesphotonsto transmitelectromagnetic wavesthrough a
vacuum, or translucent medium. Solar heat gain can be significant
even on cold clear days. Solar heat gain through windows can be
reduced byinsulated glazing, shading, and orientation. Windows are
particularly difficult to insulate compared to roof and
walls.Convective heat transferthrough and aroundwindow
coveringsalso degrade its insulation properties.[13]When shading
windows, external shading is more effective at reducing heat gain
than internalwindow coverings.[13]Western and eastern sun can
provide warmth and lighting, but are vulnerable to overheating in
summer if not shaded. In contrast, the low midday sun readily
admits light and warmth during the winter, but can be easily shaded
with appropriate length overhangs or angled louvres during summer
and leaf bearing summer shade trees which shed their leaves in the
fall. The amount of radiant heat received is related to the
locationlatitude,altitude,cloud cover, and seasonal / hourlyangle
of incidence(seeSun pathandLambert's cosine law).Another passive
solar design principle is that thermal energy can bestoredin
certain building materials and released again when heat gain eases
to stabilizediurnal(day/night) temperature variations. The complex
interaction ofthermodynamicprinciples can becounterintuitivefor
first-time designers. Precisecomputer modelingcan help avoid costly
construction experiments.Site specific considerations during
design[edit] Latitude,sun path, andinsolation(sunshine) Seasonal
variations in solar gain e.g. cooling orheating degree days,
solarinsolation,humidity Diurnalvariations in temperature
Micro-climatedetails related to breezes, humidity, vegetation and
land contour Obstructions / Over-shadowing - to solar gain or local
cross-windsDesign elements for residential buildings in temperate
climates[edit] Placement of room-types, internal doors & walls,
& equipment in the house. Orienting the building to face the
equator (or a few degrees to the East to capture the morning
sun)[8] Extending the building dimension along the east/west axis
Adequately sizing windows to face the midday sun in the winter, and
be shaded in the summer. Minimising windows on other sides,
especially western windows[13] Erecting correctly sized,
latitude-specific roof overhangs,[14]or shading elements
(shrubbery, trees, trellises, fences, shutters, etc.)[15] Using the
appropriate amount and type ofinsulationincluding radiant barriers
and bulk insulation to minimise seasonal excessive heat gain or
loss Usingthermal massto store excess solar energy during the
winter day (which is then re-radiated during the night)[16]The
precise amount of equator-facing glass and thermal mass should be
based on careful consideration of latitude, altitude, climatic
conditions, and heating/coolingdegree dayrequirements.Factors that
can degrade thermal performance: Deviation from ideal orientation
and north/south/east/west aspect ratio Excessive glass area
('over-glazing') resulting in overheating (also resulting in glare
and fading of soft furnishings) and heat loss when ambient air
temperatures fall Installing glazing where solar gain during the
day and thermal losses during the night cannot be controlled easily
e.g. West-facing, angled glazing, skylights[17] Thermal losses
through non-insulated or unprotected glazing Lack of adequate
shading during seasonal periods of high solar gain (especially on
the West wall) Incorrect application ofthermal massto modulate
daily temperature variations Open staircases leading to unequal
distribution of warm air between upper and lower floors as warm air
rises High building surface area to volume - Too many corners
Inadequateweatherizationleading to high air infiltration Lack of,
or incorrectly installed,radiant barriersduring the hot season.
(See alsocool roofandgreen roof) Insulation materialsthat are not
matched to the main mode of heat transfer (e.g. undesirable
convective/conductive/radiantheat transfer)Efficiency and economics
of passive solar heating[edit]Technically, PSH is highly efficient.
Direct-gain systems can utilize (i.e. convert into "useful" heat)
65-70% of the energy of solar radiation that strikes the aperture
or collector.Passive solar fraction (PSF) is the percentage of the
required heat load met by PSH and hence represents potential
reduction in heating costs. RETScreen International has reported a
PSF of 20-50%. Within the field ofsustainability, energy
conservation even of the order of 15% is considered
substantial.Other sources report the following PSFs: 5-25% for
modest systems 40% for "highly optimized" systems Up to 75% for
"very intense" systemsIn favorable climates such as the southwest
United States, highly optimized systems can exceed 75% PSF.[18]For
more information seeSolar Air HeatKey passive solar building design
concepts[edit]There are six primary passive solar energy
configurations:[19] directsolar gain indirect solar gain isolated
solar gain heat storage insulation and glazing passive
coolingDirect solar gain[edit]Direct gain attempts to control the
amount of directsolar radiationreaching the living space. This
direct solar gain is a critical part of passive solar house
designation as it imparts to a direct gain.The cost effectiveness
of these configurations are currently being investigated in great
detail and are demonstrating promising results.[20]Indirect solar
gain[edit]Indirect gain attempts to control solar radiation
reaching an area adjacent but not part of the living space. Heat
enters the building through windows and is captured and stored
inthermal mass(e.g. water tank, masonry wall) and slowly
transmitted indirectly to the building
throughconductionandconvection. Efficiency can suffer from slow
response (thermal lag) and heat losses at night. Other issues
include the cost ofinsulated glazingand developing effective
systems to redistribute heat throughout the living area.Isolated
solar gain[edit]Isolated gain involves utilizing solar energy to
passively move heat from or to the living space using a fluid, such
as water or air by natural convection or forcedconvection. Heat
gain can occur through a sunspace,solariumor solar closet. These
areas may also be employed usefully as a greenhouse or drying
cabinet. An equator-side sun room may have its exterior windows
higher than the windows between the sun room and the interior
living space, to allow the low winter sun to penetrate to the cold
side of adjacent rooms. Glass placement and overhangs prevent solar
gain during the summer.Earth cooling tubesor otherpassive
coolingtechniques can keep a solarium cool in the summer.Measures
should be taken to reduce heat loss at night e.g. window coverings
or movable window insulationExamples: Thermosiphon Barra system
Double envelope house Thermal buffer zone[21] Solar space
heatingsystem Solar chimneyHeat storage[edit]The sun doesn't shine
all the time. Heat storage, orthermal mass, keeps the building warm
when the sun can't heat it.In diurnal solar houses, the storage is
designed for one or a few days. The usual method is a
custom-constructed thermal mass. This includes aTrombe wall, a
ventilated concrete floor, a cistern, water wall or roof pond. It
is also feasible to use the thermal mass of the earth itself,
either as-is or by incorporation into the structure by banking or
using rammed earth as a structural medium.[22]In subarctic areas,
or areas that have long terms without solar gain (e.g. weeks of
freezing fog), purpose-built thermal mass is very expensive. Don
Stephens pioneered an experimental technique to use the ground as
thermal mass large enough for annualized heat storage. His designs
run an isolated thermosiphon 3m under a house, and insulate the
ground with a 6m waterproof skirt.[23]Insulation[edit]Main
article:Building insulationThermal
insulationorsuperinsulation(type, placement and amount) reduces
unwanted leakage of heat.[9]Some passive buildings are
actuallyconstructed of insulation.Special glazing systems and
window coverings[edit]Main articles:Insulated glazingandWindow
coveringThe effectiveness of directsolar gainsystems is
significantly enhanced by insulative (e.g.double glazing),
spectrally selective glazing (low-e), or movable window insulation
(window quilts, bifold interior insulation shutters, shades,
etc.).[24]Generally, Equator-facing windows should not employ
glazing coatings that inhibit solar gain.There is extensive use of
super-insulated windows in theGermanPassive Housestandard.
Selection of different spectrally selective window coating depends
on the ratio of heating versus coolingdegree daysfor the design
location.Glazing selection[edit]Equator-facing glass[edit]The
requirement for vertical equator-facing glass is different from the
other three sides of a building.Reflective window coatingsand
multiple panes of glass can reduce useful solar gain. However,
direct-gain systems are more dependent ondouble or triple glazingto
reduce heat loss. Indirect-gain and isolated-gain configurations
may still be able to function effectively with only single-pane
glazing. Nevertheless, the optimal cost-effective solution is both
location and system dependent.Roof-angle glass /
Skylights[edit]Skylights admit harsh direct overhead sunlight and
glare[25]either horizontally (a flat roof) or pitched at the same
angle as the roof slope. In some cases, horizontal skylights are
used with reflectors to increase the intensity of solar radiation
(and harsh glare), depending on the roofangle of incidence. When
the winter sun is low on the horizon, most solar radiation reflects
off of roof angled glass ( theangle of incidenceis nearly parallel
to roof-angled glass morning and afternoon ). When the summer sun
is high, it is nearly perpendicular to roof-angled glass, which
maximizes solar gain at the wrong time of year, and acts like a
solar furnace. Skylights should be covered and well-insulated to
reducenatural convection( warm air rising ) heat loss on cold
winter nights, and intense solar heat gain during hot
spring/summer/fall days.The equator-facing side of a building is
south in the northern hemisphere, and north in the southern
hemisphere. Skylights on roofs that face away from the equator
provide mostly indirect illumination, except for summer days when
the sun rises on the non-equator side of the building (depending
onlatitude). Skylights on east-facing roofs provide maximum direct
light and solar heat gain in the summer morning. West-facing
skylights provide afternoon sunlight and heat gain during the
hottest part of the day.Some skylights have expensive glazing that
partially reduces summer solar heat gain, while still allowing some
visible light transmission. However, if visible light can pass
through it, so can some radiant heat gain (they are
bothelectromagnetic radiationwaves.You can partially reduce some of
the unwanted roof-angled-glazing summer solar heat gain by
installing a skylight in the shade ofdeciduous(leaf-shedding)
trees, or by adding a movable insulated opaque window covering on
the inside or outside of the skylight. This would eliminate the
daylight benefit in the summer. If tree limbs hang over a roof,
they will increase problems with leaves in rain gutters, possibly
cause roof-damaging ice dams, shorten roof life, and provide an
easier path for pests to enter your attic. Leaves and twigs on
skylights are unappealing, difficult to clean, and can increase the
glazing breakage risk in wind storms."Sawtooth roof glazing" with
vertical-glass-only can bring some of the passive solar building
design benefits into the core of a commercial or industrial
building, without the need for any roof-angled glass or
skylights.Skylights provide daylight. The only view they provide is
essentially straight up in most applications. Well-insulatedlight
tubescan bring daylight into northern rooms, without using a
skylight. A passive-solar greenhouse provides abundant daylight for
the equator-side of the building.Infraredthermographycolor thermal
imaging cameras ( used in formalenergy audits) can quickly document
the negative thermal impact of roof-angled glass or a skylight on a
cold winter night or hot summer day.The U.S. Department of Energy
states: "vertical glazing is the overall best option for
sunspaces."[26]Roof-angled glass and sidewall glass are not
recommended for passive solar sunspaces.The U.S. DOE explains
drawbacks to roof-angled glazing: Glass and plastic have little
structural strength. When installed vertically, glass (or plastic)
bears its own weight because only a small area (the top edge of the
glazing) is subject to gravity. As the glass tilts off the vertical
axis, however, an increased area (now the sloped cross-section) of
the glazing has to bear the force of gravity. Glass is also
brittle; it does not flex much before breaking. To counteract this,
you usually must increase the thickness of the glazing or increase
the number of structural supports to hold the glazing. Both
increase overall cost, and the latter will reduce the amount of
solar gain into the sunspace.Another common problem with sloped
glazing is its increased exposure to the weather. It is difficult
to maintain a good seal on roof-angled glass in intense sunlight.
Hail, sleet, snow, and wind may cause material failure. For
occupant safety, regulatory agencies usually require sloped glass
to be made of safety glass, laminated, or a combination thereof,
which reduce solar gain potential. Most of the roof-angled glass on
the Crowne Plaza Hotel Orlando Airport sunspace was destroyed in a
single windstorm. Roof-angled glass increases construction cost,
and can increase insurance premiums. Vertical glass is less
susceptible to weather damage than roof-angled glass.It is
difficult to control solar heat gain in a sunspace with sloped
glazing during the summer and even during the middle of a mild and
sunny winter day. Skylights are the antithesis ofzero energy
buildingPassive Solar Cooling in climates with an air conditioning
requirement.Angle of incident radiation[edit]The amount of solar
gain transmitted through glass is also affected by the angle of the
incidentsolar radiation.Sunlightstriking glass within 20 degrees
ofperpendicularis mostly transmitted through the glass, whereas
sunlight at more than 35 degrees from perpendicular is
mostlyreflected[27]All of these factors can be modeled more
precisely with a photographiclight meterand aheliodonoroptical
bench, which can quantify the ratio ofreflectivitytotransmissivity,
based onangle of incidence.Alternatively,passive solarcomputer
software can determine the impact ofsun path, and
cooling-and-heatingdegree daysonenergyperformance. Regional
climatic conditions are often available from local weather
services.Operable shading and insulation devices[edit]A design with
too much equator-facing glass can result in excessive winter,
spring, or fall day heating, uncomfortably bright living spaces at
certain times of the year, and excessive heat transfer on winter
nights and summer days.Although the sun is at the same altitude
6-weeks before and after the solstice, the heating and cooling
requirements before and after the solstice are significantly
different. Heat storage on the Earth's surface causes "thermal
lag." Variable cloud cover influences solar gain potential. This
means that latitude-specific fixed window overhangs, while
important, are not a complete seasonal solar gain control
solution.Control mechanisms (such as manual-or-motorized interior
insulated drapes, shutters, exterior roll-down shade screens, or
retractable awnings) can compensate for differences caused by
thermal lag or cloud cover, and help control daily / hourly solar
gain requirement variations.Home automationsystems that monitor
temperature, sunlight, time of day, and room occupancy can
precisely control motorized window-shading-and-insulation
devices.Exterior colors reflecting - absorbing[edit]Materials and
colors can be chosen to reflect or absorbsolar thermal energy.
Using information on aColorforelectromagnetic radiationto determine
itsthermal radiationproperties of reflection or absorption can
assist the choices.SeeLawrence Berkeley National Laboratory and Oak
Ridge National Laboratory:"Cool Colors"Landscaping and
gardens[edit]Main article:Energy-efficient
landscapingEnergy-efficient landscapingmaterials for careful
passive solar choices includehardscapebuilding material and
"softscape"plants. The use oflandscape designprinciples for
selection oftrees,hedges, andtrellis-pergolafeatures withvines; all
can be used to create summer shading. For winter solar gain it is
desirable to usedeciduousplants that drop their leaves in the
autumn gives year round passive solar benefits.
Non-deciduousevergreenshrubsand trees can bewindbreaks, at variable
heights and distances, to create protection and shelter from
winterwind chill.Xeriscapingwith 'mature size appropriate'native
speciesof-anddrought tolerant plants,drip irrigation, mulching,
andorganic gardeningpractices reduce or eliminate the need for
energy-and-water-intensiveirrigation, gas powered garden equipment,
and reduces the landfill waste footprint. Solar poweredlandscape
lightingand fountain pumps, and coveredswimming poolsandplunge
poolswithsolar water heaterscan reduce the impact of such
amenities. Sustainable gardening Sustainable landscaping
Sustainable landscape architectureOther passive solar
principles[edit]Passive solar lighting[edit]Main article:Passive
solar lightingPassive solar lightingtechniques enhance taking
advantage ofnaturalilluminationfor interiors, and so reduce
reliance on artificial lighting systems.This can be achieved by
careful building design, orientation, and placement of window
sections to collect light. Other creative solutions involve the use
of reflecting surfaces to admit daylight into the interior of a
building. Window sections should be adequately sized, and to
avoidover-illuminationcan be shielded with aBrise soleil,awnings,
well placed trees, glass coatings, and other passive and active
devices.[19]Another major issue for manywindowsystems is that they
can be potentially vulnerable sites of excessive thermal gain or
heat loss. Whilst high mountedclerestorywindow and
traditionalskylightscan introduce daylight in poorly oriented
sections of a building, unwanted heat transfer may be hard to
control.[28][29]Thus, energy that is saved by reducing artificial
lighting is often more than offset by the energy required for
operatingHVACsystems to maintainthermal comfort.Various methods can
be employed to address this including but not limited towindow
coverings,insulated glazingand novel materials such
asaerogelsemi-transparent insulation,optical fiberembedded in walls
or roof, orhybrid solar lighting at Oak Ridge National
Laboratory.Interior reflecting[edit]Reflecting elements, from
active andpassive daylightingcollectors, such aslight shelves,
lighter wall and floor colors,mirroredwall sections, interior walls
with upper glass panels, and clear or translucent glassed
hingeddoorsandsliding glass doorstake the captured light and
passively reflect it further inside. The light can be from passive
windows or skylights and solarlight tubesor fromactive
daylightingsources. In traditionalJapanese
architecturetheShjisliding panel doors, with
translucentWashiscreens, are an original precedent.International
style,ModernistandMid-century modernarchitecturewere earlier
innovators of this passive penetration and reflection in
industrial, commercial, and residential applications.Passive solar
water heating[edit]Main article:Solar hot waterThere are many ways
to usesolar thermal energyto heat water for domestic use. Different
active-and-passivesolar hot watertechnologies have different
location-specific economiccost benefit
analysisimplications.Fundamental passive solar hot water heating
involves no pumps or anything electrical. It is very cost effective
in climates that do not have lengthy sub-freezing, or very-cloudy,
weather conditions. Other active solar water heating technologies,
etc. may be more appropriate for some locations.It is possible to
have active solar hot water which is also capable of being "off
grid" and qualifies as sustainable. This is done by the use of a
photovoltaic cell which uses energy from the sun to power the
pumps.[citation needed]Comparison to the Passive House standard in
Europe[edit]Main article:Passive houseThere is growing momentum in
Europe for the approach espoused by thePassive House(Passivhausin
German) Institute in Germany. Rather than relying solely on
traditional passive solar design techniques, this approach seeks to
make use of all passive sources of heat, minimises energy usage,
and emphasises the need for high levels of insulation reinforced by
meticulous attention to detail in order to address thermal bridging
and cold air infiltration. Most of the buildings built to the
Passive House standard also incorporate an activeheat recovery
ventilationunit with or without a small (typically 1kW)
incorporated heating component.The energy design of Passive House
buildings is developed using a spreadsheet-based modeling tool
called the Passive House Planning Package (PHPP) which is updated
periodically. The current version is PHPP2007, where 2007 is the
year of issue. A building may be certified as a 'Passive House'
when it can be shown that it meets certain criteria, the most
important being that the annual specific heat demand for the house
should not exceed 15kWh/m2a.Design tools[edit]Traditionally
aheliodonwas used to simulate the altitude and azimuth of the sun
shining on a model building at any time of any day of the
year.[30]In modern times, computer programs can model this
phenomenon and integrate local climate data (including site impacts
such asovershadowingand physical obstructions) to predict the solar
gain potential for a particular building design over the course of
a year.GPS-basedsmartphoneapplications can now do this
inexpensively on a hand held device. These tools provide the
passive solar designer the ability to evaluate local conditions,
design elements and orientation prior to construction. Energy
performance optimization normally requires an iterative-refinement
design-and-evaluate process. There is no such thing as a
"one-size-fits-all" universal passive solar building design that
would work well in all locations.Levels of
application[edit]Pragmatic[edit]Many detached suburban houses can
achieve reductions in heating expense without obvious changes to
their appearance, comfort or usability.[31]This is done using good
siting and window positioning, small amounts of thermal mass, with
good-but-conventional insulation, weatherization, and an occasional
supplementary heat source, such as a central radiator connected to
a (solar) water heater. Sunrays may fall on a wall during the
daytime and raise the temperature of itsthermal mass. This will
thenradiateheat into the building in the evening. This can be a
problem in the summer, especially on western walls in areas with
high degree day cooling requirements. External shading, or a
radiant barrier plus air gap, may be used to reduce undesirable
summer solar gain.Annualised[edit]An extension of the "passive
solar" approach to seasonal solar capture and storage of heat and
cooling. These designs attempt to capture warm-season solar heat,
and convey it to aseasonal thermal storefor use months later during
the cold season ("annualised passive solar.") Increased storage is
achieved by employing large amounts of thermal mass orearth
coupling. Anecdotal reports suggest they can be effective but no
formal study has been conducted to demonstrate their superiority.
The approach also can move cooling into the warm season.Examples:
Passive Annual Heat Storage(PAHS) - by John Hait Annualized
Geothermal Solar(AGS) heating - by Don Stephen Earthed-roofMinimum
machinery[edit]A "purely passive" solar-heated house would have no
mechanical furnace unit, relying instead on energy captured from
sunshine, only supplemented by "incidental" heat energy given off
by lights, computers, and other task-specific appliances (such as
those for cooking, entertainment, etc.), showering, people and
pets. The use of natural convection air currents (rather than
mechanical devices such as fans) to circulate air is related,
though not strictly solar design.Passive solar building design
sometimes uses limited electrical and mechanical controls to
operate dampers, insulating shutters, shades, awnings, or
reflectors. Some systems enlist small fans or solar-heated chimneys
to improve convective air-flow. A reasonable way to analyse these
systems is by measuring theircoefficient of performance. A heat
pump might use 1 J for every 4 J it delivers giving a COP of 4. A
system that only uses a 30 W fan to more-evenly distribute 10kW of
solar heat through an entire house would have a COP of 300.Zero
Energy Building[edit]Passive solar building design is often a
foundational element of a cost-effectivezero energy
building.[32][33]Although a ZEB uses multiple passive solar
building design concepts, a ZEB is usually not purely passive,
having active mechanical renewable energy generation systems such
as:wind turbine,photovoltaics,micro hydro,geothermal, and other
emerging alternative energy sources.See also[edit]Renewable energy
portal
Energy portal
Sustainable development portal
Architecture 2030 Daylighting Energy plus house List of
low-energy building techniques List of pioneering solar buildings
Low energy building Low-energy house Earthship PlusEnergy Solar
architecture The 2010 ImperativeEnergy Rating systems House Energy
Rating(Aust.) Home energy rating(USA) EnerGuide(Canada) National
Home Energy Rating(UK)References[edit]1. Jump up^Doerr,
Thomas(2012).Passive Solar Simplified(1st ed.). Retrieved October
24, 2012.2. Jump up^"U.S. Department of Energy - Energy Efficiency
and Renewable Energy - Passive Solar Building Design". Retrieved
2011-03-27.3. Jump up^"U.S. Department of Energy - Energy
Efficiency and Renewable Energy - Energy Plus Energy Simulation
Software". Retrieved 2011-03-27.4. ^Jump up to:ab"Rating tools".
Archived fromthe originalon September 30, 2007. Retrieved
2011-11-03.5. Jump
up^http://www.srrb.noaa.gov/highlights/sunrise/fig5_40n.gif6. Jump
up^http://www.srrb.noaa.gov/highlights/sunrise/fig5_0n.gif7. Jump
up^http://www.srrb.noaa.gov/highlights/sunrise/fig5_90n.gif8. ^Jump
up to:abYour Home - Orientation9. ^Jump up to:abYour Home -
Insulation10. Jump up^"BERC - Airtightness". Ornl.gov. 2004-05-26.
Retrieved 2010-03-16.11. Jump up^Your Home - Passive Cooling12.
Jump up^"EERE Radiant Barriers". Eere.energy.gov. 2009-05-28.
Retrieved 2010-03-16.13. ^Jump up to:abcd"Glazing". Archived
fromthe originalon December 15, 2007. Retrieved 2011-11-03.14. Jump
up^Springer, John L. (December 1954)."The 'Big Piece' Way to
Build".Popular Science165(6): 157.15. Jump up^Your Home -
Shading16. Jump up^Your Home - Thermal Mass17. Jump
up^"Introductory Passive Solar Energy Technology Overview". U.S.
DOE - ORNL Passive Solar Workshop. Retrieved 2007-12-23.18. Jump
up^"Passive Solar Design". New Mexico Solar Association.19. ^Jump
up to:abChiras, D. The Solar House: Passive Heating and Cooling.
Chelsea Green Publishing Company; 2002.20. Jump up^"Zero Energy
Buildings". Fsec.ucf.edu. Retrieved 2010-03-16.21. Jump up^"Two
Small Delta Ts Are Better Than One Large Delta T". Zero Energy
Design. Retrieved 2007-12-23.22. Jump up^Earthships23. Jump
up^Annualized Geo-Solar Heating, Don Stephens- Accessed
2009-02-0524. Jump up^Shurcliff, William A..Thermal Shutters &
Shades - Over 100 Schemes for Reducing Heat Loss through Windows
1980.ISBN0-931790-14-X.25. Jump up^"Florida Solar Energy Center -
Skylights". Retrieved 2011-03-29.26. Jump up^"U.S. Department of
Energy - Energy Efficiency and Renewable Energy - Sunspace
Orientation and Glazing Angles". Retrieved 2011-03-28.27. Jump
up^"Solar Heat Gain Through Glass". Irc.nrc-cnrc.gc.ca. 2010-03-08.
Retrieved 2010-03-16.28. Jump up^"[ARCHIVED CONTENT] Insulating and
heating your home efficiently: Directgov - Environment and greener
living". Direct.gov.uk. Retrieved 2010-03-16.29. Jump up^"Reduce
Your Heating Bills This Winter - Overlooked Sources of Heat Loss in
the Home". Allwoodwork.com. 2003-02-14. Retrieved 2010-03-16.30.
Jump up^[1][dead link]31. Jump up^"Industrial Technologies Program:
Industrial Distributed Energy". Eere.energy.gov. Retrieved
2010-03-16.32. Jump up^"Cold-Climate Case Study for Affordable Zero
Energy Homes: Preprint"(PDF). Retrieved 2010-03-16.33. Jump
up^"Zero Energy Homes: A Brief Primer"(PDF). Retrieved
2010-03-16.External links[edit] www.solarbuildings.ca- Canadian
Solar Buildings Research Network www.eere.energy.gov- US Department
of Energy (DOE) Guidelines www.climatechange.gov.au- Australian
Dept of Climate Change and Energy Efficiency www.ornl.gov- Oak
Ridge National Laboratory (ORNL) Building Technology
www.FSEC.UCF.edu- Florida Solar Energy Center
www.ZeroEnergyDesign.com- 28 Years of Passive Solar Building Design
[2]- Prefabricated Passive Solar Home Kits Passive Solar Design
Guidelines http://www.solaroof.org/wiki
www.PassiveSolarEnergy.info- Passive Solar Energy Technology
Overview www.yourhome.gov.au/technical/index.html- Your Home
Technical Manual developed by the Commonwealth of Australia to
provide information about how to design, build and live in
environmentally sustainable homes.
amergin.tippinst.ie/downloadsEnergyArchhtml.html- Energy in
Architecture, The European Passive Solar Handbook, Goulding J.R,
Owen Lewis J, Steemers Theo C, Sponsored by the European
Commission, published by Batsford 1986, reprinted 1993[show]Error:
Page does not existDesign
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Home Site Analysis Site Use Passive Design Controlling
temperature with passive design: an introduction Location,
orientation and layout Insulation Thermal mass Shading Ventilation
Daylighting Glazing and glazing units Controlling indoor air
quality Controlling noise Climate change Water Material Use Energy
Wet Areas Health and Safety Other Resources
Passive DesignDesigning the building and the spaces within it to
benefit from natural light, ventilation and even temperatures.
Passive DesignPassive design is the key to sustainable building.It
responds to local climate and site conditions to maximise building
users comfort and health while minimising energy use.It achieves
this by using free, renewable sources of energy such as sun and
wind to provide household heating, cooling, ventilation and
lighting, thereby reducing or removing the need for mechanical
heating or cooling. Using passive design can reduce temperature
fluctuations, improve indoor air quality and make a home drier and
more enjoyable to live in.It can also reduce energy use and
environmental impacts such as greenhouse gas emissions.Interest in
passive design has grown, particularly in the last decade or so, as
part of a movement towards more comfortable and resource-efficient
buildings.Key features of passive designThe key elements of passive
design are: building location and orientation on the site; building
layout; window design; insulation (including window insulation);
thermal mass; shading; and ventilation. Each of these elements
works with others to achieve comfortable temperatures and good
indoor air quality.The first step is to achieve the right amount of
solar access enough to provide warmth during cooler months but
prevent overheating in summer. This is done through a combination
of location and orientation, room layout, window design and
shading.Insulation and thermal mass help to maintain even
temperatures, while ventilation provides passive cooling as well as
improving indoor air quality.All of these elements work alongside
each other and therefore should be considered holistically. For
example, large windows that admit high levels of natural light
might also result in excessive heat gain, especially if they cast
light on an area of thermal mass. Similarly, opening windows that
provide ventilation will also let in noise.Alongside passive design
features, designers should also consider other factors such as
views, covenants and local authority restrictions, and building
owners preferences.Passive design in new and existing buildingsIt
costs little or nothing to incorporate passive design into a new
building. The benefits are greatest when passive design principles
are incorporated into the entire design and build process, from
site selection onwards.Once a building is completed, some passive
design features can be incorporated during later upgrades for
example, insulation can be improved, and it may be possible to
alter room layout to improve orientation and solar access.But it
may be difficult to achieve the full benefits. For example, it will
not be practical to turn a completed house around on the site to
take better advantage of sun or cooling breezes. Controlling
temperature with passive design: an introduction Location,
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Supplies5. Acoustical Properties of Building MaterialsAcoustical
Properties of Building MaterialsBy Jagg Xaxx, eHow Contributor
Share Print this articleWood is a building material that absorbs
sound.It's common to consider the durability, cost and aesthetic
appeal of building materials when building a new home, but builders
and homeowners often neglect acoustics. A beautiful home can become
a headache if sound carries through it too easily, or if every
sound has an echo. You can control the acoustics of your new home
to some extent by considering what materials to use during the
design process. Have a question? Get an answer from a Handyman
now!Other People Are Reading Acoustic Properties of Materials List
of Acoustic Materials1. Principles Vibrations in the air and in
materials carry sound through a room. When these vibrations hit a
flat, hard surface, they rebound into the room, causing an echo.
When sound waves hit a surface that is susceptible to vibration,
the material in the wall transfers the sound into the next room
rather than stopping or reflecting it. Thus, a solid concrete room
will be prone to echoes while a room framed with wood and sheathed
with drywall will not be soundproof. Providing an absorbent,
roughly textured surface such as a wall full of books decreases
both sound transfer and echoes.Materials Concrete is very effective
at reducing sound transfer from one room to another, but will
create echoes within a room if left in its natural state. Wood
reduces both sound transfer and echoing, unless it is installed in
large, flat walls with nothing breaking it up. You can make a
hardwood floor more acoustically pleasing by placing a thick wool
carpet in the middle to absorb ambient sound. Wool and other
carpets, soft and upholstered furniture and textile wall hangings
all contribute to an aurally pleasing environment. Echoes Most
people have had the experience of walking through a brand new house
with nothing in it and listening to the strange echoes. In a
lived-in house, the shapes, materials and surfaces break up sound
waves and create an environment in which vibrations can't bounce
back and forth, which is why you don't hear echoes in your home. If
you have large rooms that feature concrete walls, concrete floors
and concrete ceiling surfaces and very few possessions, then you
may notice echoes.Soundproofing Some types of wall insulation are
made specifically for soundproofing. These acoustic batts are
installed inside of framed walls in the same way as heat
insulation, but are designed to dampen sound vibrations. You can
further soundproof walls by sheathing them with plywood and
screwing drywall over the plywood. This greatly reduces the
vibrational characteristics of the drywall and eliminates sound
passing from one room to another. For a truly soundproofed room,
build a double row of studs with insulation in between them. Most
sound that passes between rooms is carried through the wall
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HOME NEWS NOTES OLD QUESTIONS QUESTION SOLUTIONS
ARTICLESAcoustical properties of building materialsAPRIL 03,
2013SAJANNO COMMENTSAcoustical properties of building
materialsSound it is anything that can be heard. In other words, it
is the sensation caused by a vibrating medium acting on the air.
Source of sound is most often vibrating solid body. The medium
conveying sound to ear can be gas, liquid or solid. It is
transmitted as the longitudinal wave motion. i.e. successive
compression- rarefaction of molecules. In solid body, the
transmission is by lateral motion. Wave length determines pitch of
sound. Higher the frequency, higher would be pitch. Frequency is
the waves per unit time. Sound is the product of frequency and wave
length. Loudness depends on distance from vibrating body.Ranges of
hearing frequency are 20 Hz to 20 kHz.1. Infra sound frequency less
than 20 Hz2. Audible sound frequency ranges between 20 Hz t-
20kHz3. Ultra sound frequency greater than 20 kHz Reactions produce
by sound1. Reflections from walls, floors, ceiling etc.2.
Absorption by floors, by ceiling, by furniture etc.3. Transmission
to adjacent room Sound classification1. Air borne sound sound
through air to air.2. Impact of structure borne sound sound through
direct contact, such as footsteps, hammering or vibration etc. it
is very sharp and troublesome.AcousticsAcoustic is the science of
soundIt assures the optimum conditions for producing and listening
to speech and musicThe panning of acoustical design has to provide
for dissipation of noise and insulation against soundNoise and its
effect1. Annoyance- irritation2. Disturbance of sleep3. Interface
of disturbing conversation4. Damage of earMeasurement of annoyance
is subjective attitude and depends upon with mental and physical
well being of listeners with their experience Magnitude of noise
levelTypes of soundsNoise level (dB)Effects
Light road trafficMedium road trafficsHeavy road trafficsRail
trafficsAir traffics60-7070-8080-9090-100>130 Physiological
effect (annoyance) Physiological effect (annoyance) Prolonged
exposure causes permanent hearing loss Prolonged exposure causes
damage to auditory organ Causes pain Instantaneous loss of
hearing
Defects due to reflected sound1. Echoes2. ReverberationEcho is
the reflected sound and heard just after the produced as a
repetitionReverberation is the continuous reflection of produced
sound waves (reflection, inter-reflection etc) until they are
gradually faded outCertain amount of reverberation is necessary to
enhance the sound, but excessive is damaging to clarity.
Reverberation timeIt is the time taken for sound energy to decay by
below annoyance level (60dB) after the sound source has stopped. It
depends on, volume of room, absorption in walls roofs and floors
etc. it has to be minimized using sound absorbing materials. Sound
insulation1. Sound absorption (prevention of reflection)2. Sound
insulation (prevention of transmission) Sound absorbents1. Porous
materials2. Resonant panel3. Cavity resonators4. Composite typesIn
porous materials, the sound waves on striking its surface enter to
the pores, vibrate inside and die-out there. Normally these
materials are soft and have large pores with interconnected
channels.Resonant panels are semi-hard in the form of porous fiber
boards that acts as sound absorbent. These boards are fixed on
timber frame with air gap between and also with wall backing. In
the resonant panels, the sound pressure waves cause vibration and
this vibration is absorbed by air gap (space) called damping.
Porous materials may also be put in the gap between boards. It is
suitable for low frequency waves.Cavity resonators are the chambers
with the narrow openings. The absorption of sound takes place in
the case by the resonance of air.Composite types are the perforated
panels fixed with air space containing porous absorbents. The
panels may be of metal, plywood, hard board, plaster board etc. the
perforation should be at least 10 percent of area high frequency
sounds are absorbed in this perforated panel.
Acoustic insulation materialsIncoming search terms: Porous
absorbents in buildings sound properties of building materials
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HOME NEWS NOTES OLD QUESTIONS QUESTION SOLUTIONS ARTICLESNoise
control and constructional precautions to reduce noiseAPRIL 05,
2013SAJANNO COMMENTSThe Noise control and constructional
precautions to reduce noise are as follows :- General
consideration1. Isolate sound source2. Proper orientation of
building , i.e. no opening towards noise3. Properly planned rooms
in building4. Furnishing materials in room helps sound absorption5.
Partitions Ridge and Movable6. Control of impact sound i.e. sue of
resilient materials as carpets in floor7. Discontinuing the path of
vibration by using sound absorbing materials8. Use of headphones
and air plugs in case of high sound. Construction materials1. Wall
partitionsAbsorbents in the Wall partitions act as the barriers to
air borne sound transmissionTypes Rigid and homogeneous
partitionsInsulation in this case depends on the weight of the
partition per unit area and increases with thickness.Following
table illustrates the insulation properties for different walls.S.
No.Types of wallApprox. wt. of wall kg/mAverage sound reduction
dB
1.One brick wall plastered in both side49050
2.One and half brick wall plastered in both side71053
3.Cavity (50mm) with half brick in both leaves49050-53
4.Half brick or concrete with plaster both side17045
5.200 mm concrete wall18545
6.Gypsum board partition on timber frame7045
7.75mm hollow clay block with plaster both side36
Hard reflecting surface outside partition increases insulation
Partition of porous materialInsulation increase to 10% or
higherMaterial may be rigid or flexible Hollow and composite
partitionCavity is betterFilling of cavity with resilient material
is preferred2.Floors/CeilingsThere is the horizontal barrier to
noiseThey act as barrier to airborne an impact sound, but offer
poor insulation for structure borne or impact sounds or insulation
in floor, resilient surface materials, and floating floors.
Resilient surface materials on floorsCotton, wooden, carpets,
asphaltmastics,PVCcarpets, corks, etc.Softer the material used
greater would be the insulation value Floating floor
constructionProvides insulation from any other parts of structureIt
is made to rest on float over existing floor by means of resilient
materials such as, glass, wool, quilt, hair felt, cork rubber,
etc.Impact sound do not transmits.On concrete floor, partition is
constructed off the structural floor and it is independentTypes of
floating floors Concrete floor with floating concrete screed: it is
the PCC of 1:1-5:3 on resilient materials above concrete floor.
Concrete floor with floating wooden raft: it is wooden nailed to
battens forming raft on resilient quilt (20mm) Heavy concrete floor
with soft floor (resilient) finish or covering Wooden floorsIt has
the problem of impact sound3.Windows and doorsIt should be- Air
tight- Double glazed- Thickness of glass to be increased- Increase
weight of shutter4.Insulating sanitary fitting- WC be insulated,
pan to rest upon thin pad of felt, cork, rubber, etc.- Cisterns not
on wall of bed rooms, brackets be fixed with insulating materials
(clips)5.Machine mounting and insulation of machineryMachine
resting on resilient materials as steel spring, rubber, corks,
etc.Brush holders is a spring is typically used with the brush, to
maintain constant contact with the commutator. As the brush and
commutator wear down, the spring steadily pushes the brush
downwards towards the commutator. Eventually the brush wears small
and thin enough that steady contact is no longer possible or it is
no longer securely held in the brush holder, and so the brush must
be replaced.
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center! Just as much notes as you need!!! Hope you enjoy studing
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Comments TagsDECEMBER 2013
SMTWTFS
Jul
1234567
891011121314
15161718192021
22232425262728
293031
RECENT POSTS Radial and Transverse component Curvilinear Motion
of Particle Rectilinear Motion of Particle Nichol Prism Letter
Proposal Brewsters Law of Polarization of Light Diffraction through
double slit Diffraction through single slit Diffraction And Its
Types Jesus Christ 2013PADANTE. All Rights Reserved.Powered
byMandala Technologies Pvt. Ltd.