21/9/15  

1  

Green design concepts

GREEN BUILDING �  A green building is a building that has been constructed

or renovated to incorporate design techniques, technologies, and materials that lessen its dependence on fossil fuels and minimize its overall negative environmental impact.

�  “Green building” is use to describe a building with minimal site disruption that is energy, water, and resource-efficient; and has good indoor air quality, natural lighting, and acoustics, among other benefits.

GREEN BUILDING �  Efficient

�  Quality of Life

�  Protects the ecosystem

�  Improves air and water quality

�  Reduce operating cost

�  Enhance occoupant comfort

WHOLE

BUILDING

APPROACH

INTEGRATED

DESIGN

PROCESS

Green design concepts

�  The Sun and Shading Design

�  Passive Design

�  Climate analysis

�  Lighting Design

�  Human comfort

�  Thermal analysis

�  Acoustic Design

21/9/15  

2  

Why do Green DESIGN �  Buildings consume up to

40% of the total energy used

�  Sun provides more than 10,000 times the energy we currently use

�  Sustainability is ensuring that our actions today does not destroy the opportunities of the future generation.

What we will cover �  Passive Design �  Passive Cooling

�  Natural ventilation �  Evaporative cooling �  Solar Shading

�  Passive Heating �  Direct / Indirect gain �  Sun Spaces �  Trombe wall �  Roof Pond

�  Daylighting

What we will cover

�  Passive Design

and this is the Active way of cooling!!

This is Passive way of cooling…

21/9/15  

3  

Why do Passive DESIGN

�  A properly designed passive home can reduce total energy load by up to 40%.

�  Passive design concepts are used for heating, cooling and lighting purposes.

�  I m p r o v e s c o m f o r t , productivity and health.

Passive design

�  Uses only locally available energy source

�  Utilizes the natural flow paths of energy

�  Address heating, cooling and lighting of spaces

�  By induced convection currents, reflected or refracted transmission.

�  On site energy sources – solar radiation, air movement from wind and temp difference, biomass, geothermal and hydro.

Basic passive design idea is:

�  Bring in daylight, heat and airflow when beneficial and exclude them when not.

�  Store ambient energies for later distribution.

�  Correct orientation, fenestration and shading

�  Efficient envelope, thermal mass

�  Renewable energies

Major principles of passive design

� Orientation

� Glazing

�  Insulation

� Thermal mass

� Ventilation

� Zoning

21/9/15  

4  

Building orientation

�  In warm/hot climates, more east and west glazing will cause more overheating

Existing buildings

Propose site

Glazing

•  Use low U value

•  Use low-emissivity (low-e) glass

•  Double or triple glazing

Thermal mass Materials used in a building to store heat energy

Most effective when facing direct sunlight

CHB, Concrete, stone, brick, etc.

The thermal storage capacity of a material depends on its conductivity, specific heat and density

Ventilation

�  Ventilation assist with cooling the building during summer.

�  Wind direction and data for the year is necessary for ventilation analysis.

�  Natural ventilation removes stale polluted air to maintain indoor air quality

�  Night time cooling

21/9/15  

5  

Zoning planning Open floor plan

Frequently used rooms locate on the south side

Infrequently used rooms locate on the north side

use open floor plan

What we will cover

�  Passive Design �  Passive Cooling �  Natural ventilation

Natural Ventilation Cross ventilation

Night cooling

Air stratification

Stack effect

Solar chimney

Wind direction

21/9/15  

6  

Natural ventilation depth of room Rule of thumb: Single sided ventilation Cross ventilation

Natural ventilation Night cooling

•  In hot climates, night ventilation can reduce peak air temperatures next day by 1-2° C in typical office.

• Reduces the air-conditioning load.

•  Windows and ventilators are left open so the cool air reaches as many surfaces as possible in rooms.

Natural ventilation Air stratification

Buoyancy force causes air in a room to stratify, with warm layers at the top and cooler layers below.

Natural ventilation stack effect

•  Stack effect is the movement of air driven by buoyancy force. •  Stack effect is greater in taller building because of greater head of cold air.

•  The stack effect is greater if the temperature difference is greater.

21/9/15  

7  

Natural ventilation stack effect Natural ventilation solar chimney

•  The transparent wall on the sun facing side of the chimney heats the air in the chimney

•  The hot air in the chimney rises, drawing cool air through the lower rooms

•  Chimney outlet needs to be about two floors above the ceiling of the room.

Natural ventilation solar chimney What we will cover

�  Passive Design �  Passive Cooling �  Natural ventilation �  Evaporative cooling

21/9/15  

8  

Evaporative Cooling •  Latent heat of vaporisation – water absorbs energy before evaporation.

•  environmentally friendly and cost effective in dry areas

•  Wind-catchers directs wind to porous pots full of water

Samples of evaporative cooling

What we will cover

�  Passive Design �  Passive Cooling �  Natural ventilation �  Evaporative cooling �  Solar Shading

Passive cooling - Solar shading

Blocks summer sun

Use sun shading devices

Sun path of the location

Roof overhang, trellises, louvers, awning

21/9/15  

9  

Passive Cooling – Solar Shading What we will cover

�  Passive Design �  Passive Cooling �  Natural ventilation �  Evaporative cooling �  Solar Shading

�  Passive Heating

Solar data Solar data

21/9/15  

10  

Sun path - Latitude Passive solar - sun

�  Passive solar is the use of the sun in a building

�  Active solar is using sun to produce hot water or electricity.

�  PV for electric and solar thermal for hot water

What we will cover

�  Passive Design �  Passive Cooling �  Natural ventilation �  Evaporative cooling �  Solar Shading

�  Passive Heating �  Direct / Indirect gain

Solar heating – Direct heat gain

Direct heat gain •  For mild to cold climate •  Simplest and least expensive •  Sun directly heats the living area

Direct heat gain with storage •  Thermal mass

21/9/15  

11  

Solar heating – Indirect heat gain

Indirect heat gain with vents •  Heat transfer from wall by conduction •  No view or direct daylight

What we will cover

�  Passive Design �  Passive Cooling �  Natural ventilation �  Evaporative cooling �  Solar Shading

�  Passive Heating �  Direct / Indirect gain �  Sun Spaces

Solar heating – sun space Sunspace with storage from wall and floor •  Heat transfer by convection •  Sunspace may not always be occupied •  Night time heat loss is less critical – can be closed off •  Insulation needed if used as living space in night time

21/9/15  

12  

What we will cover �  Passive Design �  Passive Cooling �  Natural ventilation �  Evaporative cooling �  Solar Shading

�  Passive Heating �  Direct / Indirect gain �  Sun Spaces �  Trombe wall

Solar heating – Trombe wall Trombe wall – Thick masonry wall with dark absorbing material and faced with a layer of glass •  Simple to operate •  Provides silence and privacy to spaces •  Provides the heat during night time – living and bedrooms. •  Cleaning provision between the wall and glass

Reference •  Passive solar handbook Introduction to passive solar concepts

•  Passive solar industries council, passive solar design strategies: guidelines for home building

•  Bre press, Environmental design guide

•  Gaisma website, weather data

•  US Department of energy, weather data

•  Climate consultant