DEPARTMENT OF ARCHITECTURE,SCHOOL OF ENVIRONMENTAL TECHNOLOGY,

FEDERAL UNIVERSITY OF TECHNOLOGY AKURE, ONDO STATE.

COURSE:APPLIED CLIMATOLOGY.

(ARC 810).

TOPIC:USE OF SOLAR HEATERS IN RESIDENTIAL BUILDINGS.

WRITTEN BY:OLAWORE, JOSEPH OLANREWAJU.

MATRIC NO.:ARC / 03 / 1943.

IN PARTIAL FULFILMENT OF THE REQUIREMENT FOR THE AWARD OF M.Tech ARCHITECTURE.

LECTURER:PROF. O. O. OGUNSOTE.

September, 2011.

TABLE OF CONTENTS

Abstract……………………………………………………………………………………....3

CHAPTER ONE……………………………………………………………………………..4

1.0. INTRODUCTION…………………………………………………….......…………4

CHAPTER TWO…………………………………………………………………………….6

2.0. SOLAR HEATING………………………………………………………….….……62.1. SOLAR RADIATION…………………………………………………..…...62.2. COLLECTOR ANGLE………………………………………………..…….8

CHAPTER THREE………………………………………………………………………….9

3.0. PASSIVE SOLAR HEATING……………………………………………..………..9

3.1.1. HOW PASSIVE SOLAR HEATING WORKS……………………………..9

3.1.2. PASSIVE SOLAR DESIGN PRINCIPLES………………...……………...10

3.1.3. PREVENTING HEAT LOSS…………………………………..…………..11

3.1.4. THERMAL MASS AND THERMAL LAG…………………..…………...11

3.2. ACTIVE SOLAR HEATING…………………………………………………..12

3.2.1. SOLAR LIQUID HEATING………………………..……………………...12

3.2.2. SOLAR AIR HEATING.......................................................................13

3.2.3. ECONOMIC BENEFIT OF ACTIVE SOLAR HEATING.......................14

CHAPTER FOUR…………………………………………………………………………..15

4.0 SOLAR HEATERS…………………………………………………………...……..15 4.1. SELECTING A SOLAR HEATER..........................................................15

4.2. INSTALLING AND MAINTAINING SOLAR HEATERS………..……..15

4.3 TYPES OF SOLAR HEATERS……………………………………………16

4.3. RULE OF THUMBS…………………………………...…………………..16

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4.4. BENEFITS OF SOLAR HEATERS………………………………….……17

5.0. PICTURE GALLERY OF SOLAR HEATERS ON ROOF TOP AND WALLS....18

6.0. CONCLUSION……………………………………………………………………..19

REFERENCES…………………………………………………………………………..…20

ABSTRACT

Conventional energy is finite and fast depleting. On the other hand, the demand for energy is

rising exponentially. Extensive use of solar energy is the only way to address this dichotomy. We

all know that more energy hits the earth from the sun in one hour than the whole world uses all

year. Yet only a fraction of it is harnessed. Now imagine if every household or institution sets up

its own power generating station to capture the infinite and abundant energy of the sun! Not only

would they be successful in meeting their own power requirements but they would actually have

excess power that they could 'sell' back to the grid. Not only will they be able to generate their

energy on their rooftops or backyards, they will actually be getting their power on-site at a

competitive rate. This study examines the types of solar heaters and its various uses as it relates

to man and its environment. Data used were collected from literatures and on the web. The study

thus recommends various options to efficiently control and manage the solar energy.

Keywords: Solar Heaters; Residential; Buildings.

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CHAPTER ONE

1.0. INTRODUCTION

Sunlight has influenced building design since the beginning of architectural history. Advanced

solar architecture and urban planning methods were first employed by the Greeks and Chinese,

who oriented their buildings toward the south to provide light and warmth.

The common features of passive solar architecture are orientation relative to the Sun, compact

proportion (a low surface area to volume ratio), selective shading (overhangs) and thermal mass.

When these features are tailored to the local climate and environment they can produce well-lit

spaces that stay in a comfortable temperature range. Socrates' Megaron House is a classic

example of passive solar design. The most recent approaches to solar design use computer

modeling tying together solar lighting, heating and ventilation systems in an integrated solar

design package. Active solar equipment such as pumps, fans and switchable windows can

complement passive design and improve system performance.

Our wood, coal, gas and oil resources were created using solar energy. A leaf is actually a solar

collector; it converts solar energy into chemical energy. Solar energy in the red and blue

spectrums powers the conversion of carbon dioxide and water into hydrocarbons. When we burn

these hydrocarbons, we get the solar energy back again. When we burn our fossil fuels, we are

consuming the product of millions of years worth of solar energy savings. Even hydro and wind

power are essentially solar energy in a different form. The sun evaporates water from the oceans

and raises it aloft. When it falls back as rain, it can power our hydroelectric turbines. Wind is the

result of uneven heating of the earth by the sun. Without the sun, we could not exist at all and the

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earth would be a dark and lifeless place. It is really an oxymoron to speak about solar energy and

the environment. Solar energy, in all of its forms, is the environment.

In the average residential building, most of the energy that is consumed is used to meet very

simple thermal needs. The energy for meeting these needs, such as for making domestic hot

water, or for space heat, or for drying clothes can be provided by a number of ways. You can use

oil, gas, wood, coal, electricity, nuclear energy, etc. But you can also use the suns energy directly

to meet these needs. Solar energy is free and egalitarian. It can be controlled by no one. Enough

solar energy shines upon the typical house to meet its energy needs many times over. It makes

little sense to pump oil out of the ground in some unstable and unfriendly country, and then

spend more energy to transport it half way around the earth, and then spend more energy to

refine it, and then use it for something that we could have used the sun directly for.

There is no sense in using fossil fuels that are the product of millions of years of solar energy

savings for simple tasks that we could use the sun directly for. If we will think a little about what

we are doing, we can live more sensibly without giving up our way of life. We can even save

money in the process. We can reduce consumption to a small percentage of what we would use,

with techniques that are here right now.

Existing structures can be retrofitted with high efficiency heating and cooling systems and under-

floor radiant heat. Solar can be added where possible. These measures can often reduce fossil

fuel consumption by 80%. When this solar energy comes into contact with matter, one of three

things will happen to it:

1. It may be reflected off of the matter, or

2. It may be transmitted through the matter, or

3. It may be absorbed by the matter and turned into heat.

These three phenomena have much to do with the design and use of solar collectors. There are

three main types of thermal solar collectors, low temperature, medium temperature, and high

temperature.

The low temperature solar collector has nothing to lose to the outside air environment

because it operates at or below the outside air temperature. They are the simplest and

most efficient collectors available, but they are limited to low temperatures. Heat is

transferred (and in this case lost) by Conduction, Convection and Radiation.

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The medium temperature need a construction of a heat trap; something that will let the

sun’s energy in, but not let it out. The heat can thus be trapped through Conduction,

Convection and Radiation.

The high temperature solar collector operate at high temperature when there is

conservation of more of the energy that comes into the collector through addition of

thicker insulation, additional cover sheet, evacuating air from the solar collector.

CHAPTER TWO

2.0. SOLAR HEATING

Solar space heating with air solar collectors is more popular in developed countries like USA and

Canada than heating with solar water collectors since most buildings already have a ventilation

system for heating and cooling. The solar heating process can either be passive or active.

2.1. SOLAR RADIATION

For a workable solar energy system, you should understand how the sun’s energy reaches the

earth and how this energy varies according to the time of year. The optimum climatic conditions

for solar heating are based on bright sunshine on the coldest days of the year. A solar collector is

then able to gather plenty of energy when it’s needed most.

Solar radiation reaches solar panels in three ways: as direct, diffuse, and reflected radiation. The

three types of radiation are illustrated in figure 1.

Direct radiation consists of parallel rays coming straight from the sun. This type of radiation

casts shadows on clear days. Diffuse radiation is scattered, nonparallel energy rays. This type of

radiation makes the sky blue on clear days and grey on hazy days.

Reflected radiation is solar energy received by collectors-from adjacent surfaces of the building

or ground. It depends a lot on the shape, color,

and texture of the surrounding surfaces.

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Figure 1. Three types of solar radiation: direct, diffuse & reflected

A nearly constant amount of solar radiation strikes the exterior of the earth’s atmosphere 1,350

W/m2 (429 Btu/h.ft2 ) However, a large amount of this energy is lost in the earth’s atmosphere

by absorption and reflection as it travels towards the earth’s surface. The purity of the

atmosphere, vapor, dust, and smoke content all have an effect on radiation, as does the angle of

the sun. The relative amount of radiation received on earth is diminished when the sun is lower

in the sky.

Clouds and particles in the atmosphere not only reflect and absorb solar energy, but they also

scatter it in many directions. Thus, part of the solar radiation may be diffused. Diffuse radiation,

as opposed to direct radiation, is greater on hazy days than clear ones. Diffuse radiation can

account for 50 percent of the total annual radiation for a wall facing south.

Reflected radiation from adjacent surfaces amounts to about 20 percent of the direct and diffuse

solar radiation. However, with a bright snow-covered surface in front of a solar collector, the

reflected radiation can increase to over 50 percent. Reflected radiation from adjacent surfaces,

can be a very important factor in collector sizing and placement.

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Figure 2. Sun angle for latitude of 40 N

The sun’s path at the start of summer (June 21) is at its highest position in the sky and the sun is

at its lowest position in the sky at the start of winter (December 21).

2.2. COLLECTOR ANGLE

Solar designers have traditionally recommended that collectors used for space heating

applications be sloped at the degree of latitude, plus 10° to 15°. By having the collectors at this

slope, the incident radiation is maximized during the months in which there is a space heating

requirement, however, there are other factors to consider. Unless the collectors can be supported

on a sloped roof of this angle, a collector support rack must be built.

Figure 3. Solar Radiation monthly comparison for collector slopes

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Figure 3 graphs the incident radiation on a horizontal, vertical and a 60° sloped surface in Ottawa

and illustrates that a vertical collector performs close to that of a sloped collector without any

ground reflectance. When ground reflectance is included, a vertical wall will produce from 15%

to 30% more heat than a collector at a 60 degree angle. For heating of buildings in northern

latitudes, a vertical wall is therefore the preferred surface for mounting solar collectors. There are

other advantages to vertically mounted collectors versus sloped collectors.

Incident radiation during the summer months is greatly reduced on a vertical surface, thus

reducing heat gain during these no-load periods.

The structural costs for wall-mounted systems are low.

Duct losses for wall-mounted fans are non existent.

Installation costs are lower.

CHAPTER THREE

3.0. PASSIVE SOLAR HEATING

Passive solar heating is about keeping the summer sun out and letting the winter sun in. It is the

least expensive way to heat your home. Passive solar heating is the least expensive way to heat

your home. It is also free when designed into a new home or addition, appropriate for all

climates where winter heating is required, achievable when building or renovating on any site

with solar access – often with little effort. Achievable when buying a project home, with correct

orientation and slight floor plan changes, achievable when choosing an existing house, villa or

apartment. Look for good orientation and shading, and also achievable using all types of

Australian construction systems. Passive solar heating requires careful application of the

following passive design principles:

Northerly orientation of daytime living areas.

Appropriate areas of glass on northern facades.

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Passive shading of glass.

Thermal mass for storing heat.

Floor plan zoning based on heating needs.

This will maximise winter heat gain, minimise winter heat loss and concentrate heating where it

is most needed.

3.1.1. HOW PASSIVE SOLAR HEATING WORKS

Solar radiation is trapped by the greenhouse action of correctly oriented (north facing) windows

exposed to full sun. Window frames and glazing type have a significant effect on the efficiency

of this process. Trapped heat is absorbed and stored by materials with high thermal mass (usually

masonry) inside the house. It is re-released at night when it is needed to offset heat losses to

lower outdoor temperatures.

Passive shading allows maximum winter solar gain and prevents summer overheating. This is

most simply achieved with northerly orientation of appropriate areas of glass and well designed

eaves overhangs.

Heat is re-radiated and distributed to where it is needed. Direct re-radiation is the most effective

means. Design floor plans to ensure that the most important rooms (usually day-use living areas)

face north for the best solar access. Heat is also conducted through building materials and

distributed by air movement.

Heat loss is minimised with appropriate window treatments and well insulated walls, ceilings and

exposed floors. Thermal mass must be insulated to be effective. Slab-on-ground (SOG) edges

need to be insulated if located in climate zone 8, or when in-slab heating or cooling is installed

within the slab. Air infiltration is minimised with airlocks, draught sealing, airtight construction

detailing and quality windows and doors.

Appropriate house shape and room layout is important to minimise heat loss, which occurs

mostly through the roof and then through external walls. In cool and cold climates, compact 10

shapes that minimise roof and external wall area are more efficient. As the climate gets warmer

more external wall area is appropriate.

3.1.2. PASSIVE SOLAR DESIGN PRINCIPLES

Greenhouse (Glasshouse) Principles

Passive design relies on greenhouse principles to trap solar radiation. Heat is gained when short

wave radiation passes through glass, where it is absorbed by building elements and furnishings

and re-radiated as longwave radiation. Longwave radiation cannot pass back through glass as

easily. Heat is lost through glass by conduction, particularly at night. Conductive loss can be

controlled by window insulation treatments such as close fitting heavy drapes with snug pelmets,

double glazing and other advanced glazing technology.

Orientation for Passive Solar Heating

For best passive heating performance, daytime living areas should face north. Ideal orientation is

true north and can be extended to between 15° west and 20° east of solar north. Where solar

access is limited, as is often the case in urban areas, energy efficiency can still be achieved with

careful design. Homes on poorly oriented or narrow blocks with limited solar access can employ

alternative passive solutions to increase comfort and reduce heating costs.

3.1.3. PREVENTING HEAT LOSS

Preventing heat loss is an essential component of efficient home design in most climates. It is

even more critical in passive solar design as the heating source is only available during the day.

The building fabric must retain energy collected during the day for up to 16 hours each day and

considerably longer in cloudy weather. To achieve this, careful attention must be paid to each of

the following factors.

Insulation.

Draught sealing.

Windows and glazing.

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Air locks.

3.1.4. THERMAL MASS AND THERMAL LAG

Thermal mass is used to store heat from the sun during the day and re-release it when it is

required, to offset heat loss to colder night time temperatures. It effectively ‘evens out’ day and

night (diurnal) temperature variations.

When used correctly, thermal mass can significantly increase comfort and reduce energy

consumption. Thermal mass is essential for some climates and can be a liability if used

incorrectly. Adequate levels of exposed (i.e. not covered with insulative materials such as carpet)

internal thermal mass in combination with other passive design elements will ensure that

temperatures remain comfortable all night (and successive sunless days). This is due to a

property known as thermal lag.

Thermal lag is a term describing the amount of time taken for a material to absorb and then re-

release heat, or for heat to be conducted through the material. Thermal lag times are influenced

by:

Temperature differentials between each face.

Exposure to air movement and air speed.

Texture and coatings of surfaces.

Thickness of material.

Conductivity of material.

Rates of heat flow through materials are proportional to the temperature differential between

each face. External walls have significantly greater temperature differential than internal walls.

The more extreme the climate, the greater the temperature difference.

3.2. ACTIVE SOLAR HEATING

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There are two basic types of active solar heating systems based on the type of fluid—either

liquid or air—that is heated in the solar energy collectors. (The collector is the device in which a

fluid is heated by the sun.) Liquid-based systems heat water or an antifreeze solution in a

"hydronic" collector, whereas air-based systems heat air in an "air collector."

Both of these systems collect and absorb solar radiation, then transfer the solar heat directly to

the interior space or to a storage system, from which the heat is distributed. If the system cannot

provide adequate space heating, an auxiliary or back-up system provides the additional heat.

Liquid systems are more often used when storage is included, and are well suited for radiant

heating systems, boilers with hot water radiators, and even absorption heat pumps and coolers.

Both air and liquid systems can supplement forced air systems.

3.2.1. SOLAR LIQUID HEATING

Solar water heating (SWH) or solar hot water (SHW) systems comprise several innovations and

many mature renewable energy technologies that have been well established for many years.

SWH has been widely used in Greece, Turkey, Israel, Australia, Japan, Austria and China.

In a "close-coupled" SWH system the storage tank is horizontally mounted immediately above

the solar collectors on the roof. No pumping is required as the hot water naturally rises into the

tank through thermosiphon flow. In a "pump-circulated" system the storage tank is ground or

floor mounted and is below the level of the collectors; a circulating pump moves water or heat

transfer fluid between the tank and the collectors.

SWH systems are designed to deliver hot water for most of the year. However, in winter there

sometimes may not be sufficient solar heat gain to deliver sufficient hot water. In this case a gas

or electric booster is normally used to heat the water.

3.2.2. SOLAR AIR HEATING

Solar air heating systems use air as the working fluid for absorbing and transferring solar energy.

Solar air collectors (devices to heat air using solar energy) can directly heat individual rooms or

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can potentially pre-heat the air passing into a heat recovery ventilator or through the air coil of an

air-source heat pump.

Air collectors produce heat earlier and later in the day than liquid systems, so they may produce

more usable energy over a heating season than a liquid system of the same size. Also, unlike

liquid systems, air systems do not freeze, and minor leaks in the collector or distribution ducts

will not cause significant problems, although they will degrade performance. However, air is a

less efficient heat transfer medium than liquid, so solar air collectors operate at lower efficiencies

than solar liquid collectors.

Solar air collectors are often integrated into walls or roofs to hide their appearance. For instance,

a tile roof could have air flow paths built into it to make use of the heat absorbed by the tiles. Air

entering a collector at 70°F (21.1°C) is typically warmed an additional 70°–90°F (21.1°–

32.2°C.). The air flow rate through standard collectors should be 1–3 cubic feet (0.03–0.76 cubic

meters) per minute for each square foot (0.09 square meters) of collector. The velocity should be

5–10 feet (1.5–3.1 meters) per second.

Most solar air heating systems are room air heaters, but relatively new devices called transpired

air collectors have limited applications in homes.

3.2.3. ECONOMIC BENEFIT OF ACTIVE SOLAR HEATING

Active solar heating systems are most cost-effective when they are used for most of the year, that

is, in cold climates with good solar resources. They are most economical if they are displacing

more expensive heating fuels, such as electricity, propane, and oil heat. Some states offer sales

tax exemptions, income tax credits or deductions, and property tax exemptions or deductions for

solar energy systems.

The cost of an active solar heating system will vary. Commercial systems range from $30 to $80

per square foot of collector area, installed. Usually, the larger the system, the less it costs per unit

of collector area. Commercially available collectors come with warranties of 10 years or more,

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and should easily last decades longer. The economics of an active space heating system improve

if it also heats domestic water, because an otherwise idle collector can heat water in the summer.

Heating your home with an active solar energy system can significantly reduce your fuel bills in

the winter. A solar heating system will also reduce the amount of air pollution and greenhouse

gases that result from your use of fossil fuels such as oil, propane, and natural gas for heating or

that may be used to generate the electricity that you use.

CHAPTER FOUR

4.0. SOLAR HEATERS

4.1. SELECTING A SOLAR HEATER

Selecting the appropriate solar energy system depends on factors such as the site, design, and

heating needs of your house. Local covenants may restrict your options; for example homeowner

associations may not allow you to install solar collectors on certain parts of your house (although

many homeowners have been successful in challenging such covenants).

The local climate, the type and efficiency of the collector(s), and the collector area determine

how much heat a solar heating system can provide. It is usually most economical to design an

active system to provide 40%–80% of the home's heating needs. Systems providing less than

40% of the heat needed for a home are rarely cost-effective except when using solar air heater 15

collectors that heat one or two rooms and require no heat storage. A well-designed and insulated

home that incorporates passive solar heating techniques will require a smaller and less costly

heating system of any type, and may need very little supplemental heat other than solar.

4.2. INSTALLING AND MAINTAINING SOLAR HEATERS

How well an active solar energy system performs depends on effective siting, system design, and

installation, and the quality and durability of the components. The collectors and controls now

manufactured are of high quality. The biggest factor now is finding an experienced contractor

who can properly design and install the system.

Once a system is in place, it has to be properly maintained to optimize its performance and avoid

breakdowns. Different systems require different types of maintenance, but you should figure on

8–16 hours of maintenance annually. You should set up a calendar with a list of maintenance

tasks that the component manufacturers and installer recommends.

Most solar water heaters are automatically covered under your homeowner's insurance policy.

However, damage from freezing is generally not. Contact your insurance provider to find out

what its policy is. Even if your provider will cover your system, it is best to inform them in

writing that you own a new system.

4.3. TYPES OF SOLAR HEATERS

Depending upon what works best in your case, you can build the solar heating panels in two

ways – To work inside your home or outside your home.

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Heaters that work outside your home can be fastened to your roof or the south side of your home.

Heaters that work inside your home will hang in a south-facing window. Generally, outside

heaters will create hotter temperatures and will be bigger than the inside heaters. Outside heaters

will have double-pained glass and insulated on all sides. Inside heaters may have single-pained

glass and no insulation except for some in the back.

4.4. RULE OF THUMBS

When designing your own solar air heater, these rules will help keep you on the path to success.

1) Don't let the size of the collector exceed 20 percent of the house's heated floor area, assuming

the home is reasonably well insulated and you aren't using a heat storage system.

2) Baffle layout should be such that no single "air run," the distance between an inlet and outlet,

exceeds 32 feet. Larger collectors should be divided into zones with more than one inlet and

outlet, although it could still be powered by a single fan. Or outlets could have openings into

various parts of the house or ductwork.

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3) Fan-powered air flow should equal an "actual" two cfm per square foot of collector at sea

level, and 3 cfm per square foot at an altitude of 7000 feet, because of decreasing air density.

4) The collector inlets and outlets should be of a size equal in area to the air way (between

dividers) they serve.

5) Storage. A rule of thumb on storage sizing calls for 50 -- 60 pounds of rock per square foot of

collector. The storage bin also should be proportioned for minimum surface area to minimize

storage heat loss.

6) The ideal angle to tilt the panel for the low winter sun is 62 degrees. With that in mind, it may

be better to mount your solar heating panel on a wall than a roof with a low pitch.

7) Aluminum and copper conduct heat much better than regular metal. Whichever you choose,

use the same type throughout your panel to prevent corrosion (the reaction between two different

metals).

4.5. BENEFITS OF SOLAR HEATERS

Reduce Damp

Improve air quality

Dramatically improve ventilation

Space heating

Removes condensation

Create a healthier environment for your family

Eradicate bad smells for good

Air Conditioning

5.0. PICTURE GALLERY OF SOLAR HEATERS ON ROOF TOP AND WALLS.

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Solar heating on residential building, France. Solar heating on residential building, Germany.

Solar heating on residential building. Solar heating on residential building.

Solar heating on residential building. Solar heating on residential building.

6.0. CONCLUSION

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Solar designed homes have many benefits. They cost less to operate and maintain, are warm in

the winter and cool in the summer, and are environmentally responsible.

Solar heater arrangements should be studied to facilitate blending collector panels into the

architecture of new or existing buildings. Shade trees must be so located as not to cast shadows

on the collector. Other structures such as chimneys which can cast shadows should be carefully

located to avoid shading of the collector.

Reduction of heat losses is usually one of the most important steps in the design of a solar space

heating system. It almost always costs less to super-insulate a building to reduce losses than to

provide additional solar collector area to provide the extra heat.

Systems should be designed for minimum maintenance. Maintenance of glass will be minimized

if vandalism can be reduced. Collectors of flat-roofed buildings may be shielded from the ground

by a skirt around the roof perimeter. Locating the collector in the backyard area of residences

rather than on a street-facing roof reduces probability of vandalism.

REFERENCES20

Commonwealth of Australia (1995), Australian Model Code for Residential Development

(AMCORD), AGPS Canberra.

Daniels, Farrington (1964). Direct Use of the Sun's Energy. Ballantine Books. ISBN

0345259386.

Department of the Environment, Water, Heritage and the Arts (2008), Australian Residential

Sector Baseline Energy Estimates 1990 – 2020.

Halacy, Daniel (1973). The Coming Age of Solar Energy. Harper and Row. ISBN 0380002337.

Hollo, N. (1997), Warm House Cool House: Inspirational designs for low-energy housing,

Choice Books, Australia.

http://radiantsolar.com/optionII.html

http://solarairheating.org

http://www.mobilehomerepair.com/solarrules.php

http://www.tatabpsolar.com/index.php

http://en.wikipedia.org

Mazria, Edward (1979). The Passive Solar Energy Book. Rondale Press. ISBN 0878572384.

Robert J. Starr (2007), Energy Efficiency And The Environment: Resource Solar And

Environment.

Schittich, Christian (2003). Solar Architecture (Strategies Visions Concepts). Architektur-

Dokumentation GmbH & Co. KG. ISBN 3764307471.

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