SOLAR PASSIVE ARCHITECTURE

G.Daniel

M.E Solar Energy

CEG

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Introduction

Solar energy collection, storage and distribution are done by natural means.

No electrical or mechanical power and electrical control systems are used.

The elements of the buildings are architecturally integrated to participate in collection, storage and distribution of thermal energy.

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Examples of solar passive heating in the past

Montezuma’s castle Native indian dwellings in Chacko

Canyon and Mesa Verde.

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Montezuma’s Castle

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Chacko Canyon Dwellings

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Mesa Verde Dwellings

PASSIVE SOLAR HEATING

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Site specific considerations Latitude, sun path, and insolation (sunshine) Seasonal variations in solar gain e.g. cooling

or heating degree days (CDD or HDD), solar insolation, humidity

Diurnal variations in temperature Micro-climate details related to breezes, humidity,

vegetation and land contour Obstructions / Over-shadowing - to solar gain or

local cross-winds

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Classification of passive heating

Direct gain Thermal storage wall Attached sunspace Thermal storage roof Convective loop

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Direct gain It is the simplest form of passive heating. A double glazed window facing south is used. An appropriate over hanging is provided to shade the

room during summer. The walls and floor are made massive to act as thermal

mass. Effectiveness of this system depends upon U-value e-

value of the glazing and building materials.

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Direct gain

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Thermal storage wall This is also known as trombe wall. Here there is space between the glazing and a thermal

storage wall. The air gap is around 10 to 15 cm. Air is circulated by natural convection. The flow of heat can be changed by adjusting the

dampers. Air temperature can reach temperatures of about 60°C. The opening area of vents is calculated by,

A= (L x H) / 100

where,

A = area of vents

L = length of wall

H = distance between top and bottom vents

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Thermal storage wall

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Attached greenhouse (Sunspace)

In this direct gain and thermal storage wall concepts are combined.

In this type, there are 2 zones in the building. Zone 1 is called the sunspace and Zone 2 is

called living space. There is a thermal storage wall between zone1

and zone2. The heat is collected by the thermal storage wall

and supplied to the living space when required.

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Attached greenhouse

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Thermal storage roof

It was developed by Hay and Yellot in Arizona. It is similar to the thermal storage wall but the

thermal mass is the roof instead of the wall. The various components of thermal storage roof

are :- A metallic roof- Water bags or thermal storage materials- Movable insulation

Instead of water bags, a roof pond system can be used. This is also called Skytherm system.

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Thermal storage roof

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Convective loop

This is similar to an active heating approach as there is a separate collector and storage system.

The various components of a convective loop system are :

A liquid or air solar flat plate collectorA pebble bed storage system

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Convective loop

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QUERIES

PASSIVE SOLAR COOLING

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Classification of passive cooling

Shading Ventilation Evaporation Ground coupling

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Shading The most effective way of cooling a building is to

shade the windows, walls and roofs. The direct solar radiation can be controlled by

sunshades, plants and overhangs. The horizontal louvres placed in south direction

should be sized. Planting trees and shrubs also facilitate shading.

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Shading

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Ventilation Moving air below 37°C provides a cooling

sensation. Pattern of air flow depends on location of inlet and

outlet of air. The various ventilation strategies are:

Solar chimney ( stack effect)Wind catcher

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Ventilation

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Ventilation

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Ventilation

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Evaporation Evaporation of water from roof top. Evaporative cooling can be done in the following

ways:Roof pondThin water filmFlow of waterSpray of water

It is more effective in dry regions.

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Ground Coupling The ground temperature is always less that air

temperature. Cooling is obtained by partially sinking the building

below ground level. Sometimes the building is earth bermed to

maintain constant temperature. Earth air tunnels can also be used to provide

cooling.

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QUERIES

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