Passive Solar Design of Buildings – A Case Study

Sanjiv Kumar* and Manjeet Bansal**

*
Department of Civil Engineering, GZS College of Engineering & Technology,
Bathinda, India, sanjiv_aggarwal@rediffmail.com
**
Department of Civil Engineering, GZS College of Engineering & Technology,
Bathinda, India, push_kar5@yahoo.com

ABSTRACT proven, over time, to be better applications for passive use

of solar energy.
Passive solar technologies are means of using sunlight
for useful energy without use of active mechanical systems, 2 PASSIVE SOLAR DESIGN OF
as contrasted to active solar techniques. The scientific basis BUILDINGS
for passive solar building design has been developed from a
combination of climatology, thermodynamics, particularly Passive solar design refers to the use of the sun’s
heat transfer, and human thermal comfort. Specific energy for the heating and cooling of living spaces. In this
attention is directed to the site and location of the dwelling, approach, the building itself or some element of it takes
the prevailing climate, design and construction, solar advantage of natural energy characteristics in materials and
orientation, placement of glazing-and-shading elements, air created by exposure to the sun. Passive systems are
and incorporation of thermal mass. The Solar Passive simple, have few moving parts, and require minimal
Complex of Punjab Energy Development Agency (PEDA), maintenance and require no mechanical systems. Operable
at Chandigarh, India is a unique and successful model of windows, thermal mass, and thermal chimneys are common
energy efficient solar builidng, designed on solar passive elements found in passive design. Operable windows are
architecture. More than 90% reduction in lighting simply windows that can be opened. Thermal mass refers to
consumption, and more than 50% saving in overall energy materials such as masonry and water that can store heat
consumption has been achieved in this complex, which thus energy for extended time. Thermal mass will prevent rapid
provides a clean and pollution free work environment. temperature fluctuations. Thermal chimneys create or
reinforce the effect hot air rising to induce air movement for
Keywords: solar, building, architecture, energy, cooling purposes. Wing walls are vertical exterior wall
environment. partitions placed perpendicular to adjoining windows to
enhance ventilation through windows.
1 INTRODUCTION
The scientific basis for passive solar building design
Passive solar technologies are means of using sunlight has been developed from a combination of climatology,
for useful energy without use of active mechanical systems, thermodynamics, particularly heat transfer, and human
as contrasted to active solar techniques. Such technologies thermal comfort. Specific attention is directed to the site
convert sunlight into usable heat in the form of water, air, and location of the dwelling, the prevailing climate, design
thermal mass; cause air-movement for ventilating, or future and construction, solar orientation, placement of glazing-
use, with little use of other energy sources. Passive cooling and-shading elements, and incorporation of thermal mass.
is the use of the same design principles to reduce summer While these considerations may be directed to any building,
cooling requirements. Technologies that use a significant achieving an ideal solution requires careful integration of
amount of conventional energy to power pumps or fans are these principles. Modern refinements through computer
active solar technologies. Some passive systems use a small modeling and application of other technology can achieve
amount of conventional energy to control dampers, shutters, significant energy savings without necessarily sacrificing
night insulation, and other devices that enhance solar functionality or aesthetics.
energy collection, storage, use, and reduce undesirable heat
transfer. Passive solar technologies include direct and 3 ELEMENTS OF PASSIVE SOLAR
indirect solar gain for space heating, solar water heating DESIGN
systems based on the thermo-siphon, use of thermal mass
and phase-change materials for slowing indoor air Passive solar buildings range from those heated almost
temperature swings, solar cookers, the solar chimney for entirely by the sun to those with south-facing windows that
enhancing natural ventilation, and earth sheltering. Low- provide some fraction of the heating load. The difference
grade energy needs, such as space and water heating, have between a passive solar building and a conventional
building is its design, and the key is designing a passive

342 Clean Technology 2011, www.ct-si.org, ISBN 978-1-4398-8189-7

solar building to take the best advantage of the local connected to the ground, or in contact with outside air
climate. Elements of design include window location and whose temperature is lower than the desired temperature of
glazing type, insulation, air sealing, thermal mass, shading, the mass.
and sometimes, auxiliary heat. Passive solar design
techniques can be most easily applied to new buildings. 3.4 Distribution
However, existing buildings can also be adapted or
retrofitted to passively collect and store solar heat. In some This is the method by which solar heat circulates from
ways, every building is a passive solar building because it the collection and storage points to different areas of the
has windows, but designing a building to work in its building. A strictly passive design will use the three natural
climate is the basis for these techniques. Every passive heat transfer modes, i.e., conduction, convection and
solar building includes five distinct elements: the aperture, radiation exclusively. In some applications, however, fans,
absorber, thermal mass, the distribution and the control, as ducts and blowers may help with the distribution of heat
shown in Figure 1 [1]. through the building.

3.1 Aperture (Collector) 3.5 Control

This is the large glass (window) area through which The roof overhangs can be used to shade the aperture
sunlight enters the building. Typically, the aperture(s) area during summer months. Other elements that control
should face within 30º of true south and should not be under and/or overheating include: electronic sensing
shaded by other buildings or trees from 9 a.m. to 3 p.m. devices such as a differential thermostat that signals a fan to
each day during the heating season. turn on; operable vents and dampers that allow or restrict
heat flow; low-emissivity blinds and sunshades.
3.2 Absorber
4 BASIC TYPES OF PASSIVE SOLAR
This is the hard, darkened surface of the storage DESIGN
element. This surface, which could be masonry wall, floor,
or partition (phase change material), or a water container, There are three basic types of passive solar design, i.e.,
sits in the direct path of sunlight. Sunlight hits the surface direct gain, indirect gain and isolated gain that differ in how
and is absorbed as heat. the above five elements of design are incorporated. Each
performs a separate function, but all five must work
together for the system to be successful [2].

4.1 Direct Gain

Direct gain is the simplest passive design technique. In
this system, the actual living space is a solar collector, heat
absorber and distribution system. South facing glass admits
solar energy into the house where it strikes directly and
indirectly thermal mass materials in the house such as
masonry floors and walls as shown in Figure 2. The direct
gain system will utilize 60 – 75% of the sun’s energy
striking the windows. In this system, the thermal mass
floors and walls are functional parts of the house. It is also
possible to use water containers inside the house to store
heat. However, it is more difficult to integrate water storage
Figure 1: Five Elements of Passive Solar Design
containers in the design of the house. The thermal mass will
temper the intensity of the heat during the day by absorbing
3.3 Thermal Mass the heat. At night, the thermal mass radiates heat into the
living space.
These are the materials that retain or store the heat
produced by sunlight. The difference between the absorber The amount of passive solar fraction depends on the
and thermal mass, although they often form the same wall area of glazing and the amount of thermal mass. The
or floor, is that the absorber is an exposed surface whereas glazing area determines how much solar heat can be
storage is the material below or behind that surface. The collected. And the amount of thermal mass determines how
thermal mass must be insulated from the outside much of that heat can be stored. It is possible to undersize
temperature, otherwise the collected solar heat can drain the thermal mass, which results in the house overheating.
away rapidly, especially when thermal mass is directly

Clean Technology 2011, www.ct-si.org, ISBN 978-1-4398-8189-7 343

There is a diminishing return on over sizing thermal mass, The wall consists of an 8 inch to a 16 inch-thick
but excess mass will not hurt the performance. The ideal masonry wall on the south side of a house. A single or
ratio of thermal mass to glazing varies according to the double layer of glass is mounted about 1 inch or less in
climate. front of the wall’s surface. Solar heat is absorbed by the
wall’s dark colored outside surface and stored in the wall’s
mass, where it radiates into the living space. The Trombe
wall distributes or releases heat into the building over a
period of several hours. Solar heat migrates through the
wall, reaching its rear surface in the late afternoon or early
evening. When the indoor temperature falls below that of
the wall’s surface, heat begins to radiate and transfer into
the room. For example, heat travels through a masonry wall
at an average rate of 1 hour per inch. Therefore, the heat
absorbed on the outside of an 8-inch thick concrete wall at
noon will enter the interior living space around 8 p.m.

4.3 Isolated Gain – Sunspace

A sunspace is also known as a solar room or solarium.
It is a versatile approach to passive solar heating. A
sunspace can be built as part of a new building or as an
addition to an existing one. The simplest and most reliable
sunspace design is to install vertical windows with no
overhead glazing. Sunspaces may experience high heat gain
and high heat loss through their abundance of glazing. The
temperature variations caused by the heat losses and gains
can be moderated by thermal mass and low-emissivity
windows. The thermal mass that can be used include a
Figure 2: Direct Gain System
masonry floor, a masonry wall bordering the house or water
containers. The distribution of heat to the house can be
4.2 Indirect Gain – Trombe Wall accomplished through ceiling and floor level vents,
windows, doors or fans. Most builders also separate the
An indirect-gain passive solar building has its thermal sunspace from the building with doors and/or windows so
storage between the south-facing windows and the living that the comfort inside the house isn’t overly affected by the
spaces. Using a Trombe wall as shown in Figure 3 is the sunspace’s temperature variations.
most common indirect-gain approach.
Sunspaces may often be called and look a lot like
greenhouses. However, a greenhouse is designed to grow
plants while a sunspace is designed to provide heat and
aesthetics to a building. Many elements of a greenhouse
design, such as overhead and sloped glazing, which are
optimised for growing plants, are counterproductive to an
efficient sunspace. Moisture related fungus and decay,
insects and dust inherent to gardening in a greenhouse are
not especially compatible with a comfortable and healthy
living space. Also, to avoid overheating, it is difficult to
shade sloped glass, while vertical glass can be shaded with
a right-sized overhang.

5 PEDA SOLAR PASSIVE COMPLEX

The Solar Passive Complex of Punjab Energy
Development Agency (PEDA), at Chandigarh, India is a
unique and successful model of an energy efficient solar
builidng, which has been designed on solar passive
architecture, with a total covered area 68,224 sq.ft.
Figure 3: Trombe Wall or Thermal Mass Wall including 23,200 sq.ft. basement [3]. It is the centre of

344 Clean Technology 2011, www.ct-si.org, ISBN 978-1-4398-8189-7

excellence for solar buildings, minimizing conventional Wind Tower Coupled with Solar Chimneys: The wind
lighting load in the office building, efficient movement of tower centrally placed coupled with solar chimneys on the
natural air, light vaults, wind tower coupled with solar domical structures for scientific direct & indirect cooling
chimney, Water bodies, designed landscape horticulture and scientific drafting of used air.
and energy conservation activities. The main aims &
objectives of this complex are to demonstrate the Solar Insulated Roofing: All the roofs have been insulated with
Passive Architecture concepts, to educate architects, double insulation system to avoid penetration of heat from
engineers & builders for replication of concepts, and to the roof.
generate awareness among general public, teachers,
students of school and colleges. The building has the Auditorium: A unique auditorium scientifically designed
following salient design features: to control heat penetration, light & sound distribution is
placed in the north under the shade of main building.
Orientation: Solar Passive Complex has been developed in
response to solar geometry i.e. minimizing solar heat gain Big Exhibition Centre: The complex is having a proper
in cold period. The building envelope attenuates the designed exhibition centre for display of renewable & non-
outside ambient conditions and the large volume of air is conventional energy devices / equipments.
naturally conditioned by controlling solar access in
response to the climatic swings. Unique Workstations: Scientifically designed and fully
equipped unique workstations have been made for the
Solar Power Plant: 25Kwp building integrated solar employees having comfortable environment, good
photovoltaic power plant has been set up to meet the basic ergonomics with sufficient natural light and air.
requirement of electricity in the complex.
6 CONCLUSIONS
Unique Shell Roofing on Central Atrium: The central
atrium of the complex having main entrance, reception, The basic natural processes that are used in passive
water bodies, cafeteria and sitting place for visitors solar energy are the thermal energy flows associated with
constructed with hyperbolic shell roof to admit daylight radiation, conduction, and natural convection. These basic
without glare and heat coupled with defused lighting responses to solar heat lead to design elements, material
through glass to glass solar panels. The roof is supported choices and placements that can provide heating and
with very light weight space frame structure. cooling effects in a building. Key aspects of passive design
include appropriate solar orientation, the use of thermal
Water Bodies: The water bodies with waterfalls and mass, and appropriate ventilation and window placement.
fountains have been placed in the central atrium of the Passive design is practiced throughout the world and has
complex for cooling of whole the complex in the hot and been shown to produce buildings with low energy costs,
dry period. reduced maintenance, and superior comfort. In the PEDA
Passive Solar Complex in Chandigarh, more than 90%
Light Vaults: The vertical cutouts in the floating slabs are reduction in lighting consumption, and more than 50%
integrated with light vaults and solar activated naturally saving in overall energy consumption has been achieved,
ventilating, domical structures in the south to admit day which thus provides a clean and pollution free work
light without glare and heat. environment. This building heralds the beginning of the
energy efficiency movement in the non-domestic buildings
Cavity Walls: The complex is a single envelope made up such as offices, educational institutions and factories in
of its outer walls as double skin walls having 2” cavity in India.
between. The cavity walls facing south and west are filled
with further insulation material for efficient thermal effect. REFERENCES
[1] J.K. Nayak, R. Hazra, and J.A. Prajapati, “Manual
Unique Floating Slab System: The system of floating and on Solar Passive Architecture,” Solar Energy
overlapping slab with interpenetrating vertical cutouts Centre, Ministry of Non-conventional Energy
allow free and quick movement of natural air reducing any Sources, Govt. of India, New Delhi, 1999.
suffocating effect. [2] C.L. Gupta, “Solar Passive Buildings for Developing
Countries,” Proceedings of Indian Academy of
Landscape Horticulture: The space around the building Sciences (Engg. Sciences), Part 1, 77-104, 1993
inside and outside of boundary wall and a big lawn in the [3] www.peda.gov.in
south has been designed with trees, shrubs and grass. The
big trees along the boundary wall acts as a curtain to
minimize air pollution, sound pollution and filter/cool the
entry of air.

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