bioclimatic design at the site planning scale

BIOCLIMATIC DESIGN AT THE SITE PLANNING SCALEBY: DONALD WATSON & KENNETH LABS

KOMAL ARORAAMITY UNIVERSITYB.ARCH (7TH SEM)

CONTENT1. WHAT IS BIOCLIMATIC DESIGN?2. INTRODUCTION3. DESIGN TECHNIQUES4. PRINCIPLES OF BIOCLIMATIC DESIGN5. PASSIVE SYSTEM OF HEATING6. DEMAND OF BIOCLIMATIC DESIGN7. USE OF NEIGHBOURING LAND FORMS AND VEGETATION FOR WINTER

WIND8. USE OF NEIGHBOURING LAND FORMS AND VEGETATION FOR SUMMER

SHADING9. USE OF NEIGHBOURING LAND FORMS AND VEGETATION FOR SUMMER

BREEZE

BIOCLIMATIC DESIGN AT SITE PLANNING SCALE

QUESTIONS:1. What is bioclimatic design?2. What are the principles of bioclimatic design?3. Write the techniques include in bioclimatic design?4. Demand for bioclimatic design?5. What is passive cooling?6. Ways to use the surrounding land forms, vegetation and structure

to protect from winter wind and summer breezes?7. What is wind shadow?

WHAT IS BIOCLIMATIC DESIGN?• Bioclimatic design is defined as an architecture which has a

connection with nature.• The aim of bioclimatic architecture is to create urban areas and

buildings that are designed in order to fully cover their energy requirements without induce environmental damage.• This architecture seeks perfect cohesion between design and

natural elements (such as the sun, wind, rain and vegetation), leading us to an optimization of resources.


INTRODUCTION

Urban designers can create favorable microclimatic conditions in, and around buildings and outdoor spaces to increase comfort and reduce energy requirements.

In winters, the objective is to protect outdoor spaces, entryways and structures from the winter winds and to promote and gain solar heat.

In summer, it’s the reverse, to resist solar gain by shading and to promote cooling by ventilation.


BIOCLIMATIC DESIGN TECHNIQUES INCLUDE:1. WIND BREAKS(Winters): Using of neighboring land forms,

structures, or vegetation for winter wind protection.2. SUN SHADING(Summer): Sun angles are different in summer

than in winters, it is possible to shade spaces and building openings from the sun during summer period.

• Natural Ventilation: It is a concept to cool outdoor spaces and buildings by using neighboring land forms, structures, or vegetation to increase exposure to summer breezes.• Plants and Water: Several landscaping techniques provides cooling

by the use of plants and water near the building surfaces and maximize on-site evaporative cooling.


Crossed ventilation: It is a ventilation system of a space or a run of associated spaces, through openings placed on two opposite walls. This strategy should be used with the combined shaded environments and an envelope (walls and ceilings) whose surface temperature would be similar to ambient temperature. Otherwise and with not enough thermal insulation, it can be several degrees above ambient temperature, involving a heat emission which reduces the thermal comfort.

Chimney effect: It is a system that makes an air extraction by placing apertures in the top of a room. They can be connected to an exhaust vertical duct. The movement of the air is possible thanks to the stack effect. The stack effect is also referred to as the "chimney effect", and it helps drive natural ventilation and infiltration. It is the movement of air into and out of buildings, chimneys, flue gas stacks, or other containers, and is driven by buoyancy. Buoyancy occurs due to a difference in indoor-to-outdoor air density resulting from temperature and moisture differences. The result is either a positive or negative buoyancy force. The greater the thermal difference and the height of the structure, the greater the buoyancy force, and thus the stack effect.

THE MAIN PRINCIPLES OF THIS ARCHITECTURE ARE:

• The consideration of the weather, hydrography and ecosystems of the environment in which buildings are built for maximum performance with the least impact.• The efficacy and moderation in the use of construction materials,

giving priority to low energy content compared to high energy.• The reduction of energy consumption for heating, cooling,

lighting and equipment, covering the remainder of the claim with renewable energy sources.


• Protection of the buildings from the summer sun, primarily by shading but also by the appropriate treatment of the building envelope (i.e. use of reflective colours and surfaces).• The fulfilment of requirements of hydrothermal comfort,

safety, lighting and occupancy of buildings.


This $6.3 million glittering aluminium shell bears little resemblance to a traditional mountain refuge.

In the summer, water from the melting glaciers is harvested and stored in a large reservoir 40 metres up the slope.

EXAMPLE OF BIOCLIMATIC DESIGN:

Monte Rosa Hut, Switzerland

A 16kW photovoltaic system integrated into the southern facade generates 90% of the building’s electricity, with excess stored in lead-acid accumulators.

Waste water is filtered and recycled, and solar showers loosen up any aching limbs.

A digital energy management system monitors demand, and even processes weather forecasts and anticipated visitor numbers for maximum efficiency.

The Hut will also be used as a centre for research into resource efficiency by Zurich’s Federal Institute of Technology (ETH).

WHAT ARE PASSIVE SYSTEMS FOR HEATING, COOLING AND LIGHTING?1. Passive solar systems are the integrated parts – elements of a

building which function without mechanical parts or additional energy supply and are used for heating as well as cooling buildings naturally. Passive solar systems are divided into three categories:

• Passive Solar Heating Systems• Passive (Natural) Cooling Systems and Techniques• Systems and Techniques for Natural Lighting


EXAMPLE OF PASSIVE COOLING:

Inspired by the form of a lotus, Singapore’s newly opened Art Science Museum in the heart of the Marina Bay development is a striking addition to the waterfront, with ten dramatic ‘fingers’ curving up towards the sky.

Like all flowers, this too needs water and light.Architect Moshe Safdie designed the Museum to allow

natural light to illuminate the curved interior walls of the ‘fingers’ through skylights at their tips.

Its dish-like roof gathers rainwater, channelling it down a 35-foot drop at the core of the building, towards a reflective pool on the lower floor.

From here, it’s redirected to a cooling cylindrical waterfall feature, and – more prosaically – recycled for use in the museum toilets.

THE PROJECT, CALLED RB12 : Designed by the French-Brazilian architectural firm Triptyque and constructed by Natekko of France, RB12 will have a façade that can be opened to the elements, in contrast to other office buildings in the city that are fully sealed off from the climate.

The building will be the first to use photovoltaic panels for its own electricity production

A façade of double-glazed glass will optimize the use of daylighting with angled windows that should make the building glitter like a diamond, while louvered stainless steel panels control the amount and quantity of sunlight, explained the architects at Triptyque in a joint email response to questions.

Suspended gardens integrated into the façade, along with a green rooftop, also help control lighting.

The glass façade is strategically shaded to reduce the heat gain in the building from direct solar radiation, but is transparent enough to allow high levels of natural light to enter indirectly and illuminate the building.

The façade system “allows a reduction in the use of artificial lighting along the walls, and therefore power consumption and internal temperatures are also reduced,” the architectural team says.

DEMAND FOR BIOCLAMATIC DESIGN:

1. Identified as eco-friendly and cost saving, as it do not require any installation and use of over priced mechanical systems.

2. Reduces the use of refrigerants such as CFC’s (chlorofluorocarbon) from air conditioner.


USE NEIGHBOURING LAND FORMS, STRUCTURES, OR VEGETATION FOR WINTER WIND PROTECTION:

1. The range of protected area downwind is proportional to the height of the windbreak-the higher the barrier, the longer the “wind shadow”.


2. The maximum length of wind shadow is developed only when the width of the windbreak is at least 11-12 times its height.


3. The permeability or density of the barrier affects the length of the downwind protected zone. Dense and solid barriers offer greatest reduction in wind speed, but only for a short distance immediately behind the barrier.


USE NEIGHBOURING LAND FORMS, STRUCTURES, OR VEGETATION FOR WINTER WIND PROTECTION:1. Analysis of the building site should be made to determine if there

are existing wind protected area.2. Open spaces in any complex are integral part of building form. 3. Large open spaces provide free air movement.4. In siting a house, the builder should avoid open areas, hilltops and

valley floors that are directly exposed to prevailing winter wind.5. Trees, shrubs, fences and walls are the most common barrier for

wind control.6. Higher the barrier, the larger the protective “wind shadow”.


USE NEIGHBOURING LAND FORMS, STRUCTURES, OR VEGETATION FOR SUMMER SHADING: Keep understory

clear so as not to disrupt airflow for ventilation.


Plant tall canopy trees on south side of the house to shade roof and walls.

Shade planting on west and northwest side often can double as winter windbreak. Consider evergreens, fences, and walls.

Plant dense trees, shrubs, hedges on west side of the house to intercept after noon sun.


Patio cover shade the wall, it also reduces reflected gain from loading on the wall.

Attached overhead shading structures.


SITING : • Proper design of the site and the building permits utilization of

solar radiation during the cold season and protect the building from overheating by the sun during the hot season. • The suitable location of the building construction depends on

the climate, the direction of the winds, the presence of trees or other landscaping features, uses and the internal layout of the building.

On- lot development : • When the site of the house has been determined, planning of other

exterior shading devices can begin.• Using shade trees are the best, it protects the house in summer and

shed their leaves in winter to allow the house to receive solar gain.


USE NEIGHBOURING LAND FORMS, STRUCTURES, OR VEGETATION TO INCREASE EXPOSURE TO SUMMER BREEZES: Tree planting can be

used to guide wind into unit. Here tree funnel lines are “disguised” as driveway and property line planting to better blend with siting.


Side tree walls help increase driving pressure. The rear tree wall pressurizes the suction zone, reducing overall pressure differential.

Air is deflected around the entire system.

Good design allows free rear venting as well as funnel at front.

Narrow corridors at sides create air jet of increased velocity– A good place for a porch or deck.

USE NEIGHBOURING LAND FORMS, STRUCTURES, OR VEGETATION TO INCREASE EXPOSURE TO SUMMER BREEZES: The direction and

velocity of flow of summer breezes are influenced considerably by local land forms, tree masses and existing structures.


Building on the crest of the hill will maximize exposure to prevailing breezes.

On slopes and in valleys, cool air flows downhill, washing along the slope and settling in depressions or following the valley downstream near large water bodies.

A topographic analysis of the area is necessary to determine probable on-site wind flow patterns and most desirable building locations.

Trees and shrubs can be used to channel air flow towards the structure an even used to increase the air velocity.


Fences, walls, and adjacent structure can create air dams that increase the inflow pressures.


Hedges and shrubs planting out side window relieves unwanted pressure, components, fosters downward deflections of air stream.

Effect will be produced for distance ‘D’ up to 15 to 20 ft.


Tree canopy outside the window is to “lift” or wrap the airstream upward by relieving downward pressure.

Tree immediately outside the window will produce a ceiling wash flow.

Tree at a distance from the house, airstream may miss the house altogether.



USE GROUND COVER AND PLANTING FOR SITE COOLING:

Neighborhood air temperature can be kept low by minimizing the expanse of paving and by shading paved area.

SITE PLANNING SUGGESTIONS:

1. Keep paved area to a minimum an 8ft dia. Turnaround with a 20ft ring road is recommended.

2. If spillover parking areas are required use a porous paving block instead of asphalt.

3. Plant shade trees to shade paving.4. Use 18-20ft. Street width for large lot developments.5. Use 26ft. Street width for 14 acre lots.6. Avoid 34-35ft. Street widths- these are never warranted in well

planned new developments.


Porous concrete paving can be precast or cast-in-place with forms made for this purpose (grasstone) use it for stabilizing shoulders and for spillover parking spaces both on and off lot.


The air temperature in the “microclimate zone”(1-4ft.) above these surfaces also differ appreciably.

The difference in surface temperature between grass and asphalt can easily exceed 25 degree Fahrenheit.

Non-living surfaces are much hotter than grass since they don’t dissipate heat through evaporation.


MAXIMIZE ON-SITE EVAPORATIVE COOLING: Outdoor evaporative cooling mechanisms can help to provide

outdoor comfort as well as to lower indoor cooling costs by lowering air temperature surrounding the building.

Cool air is denser than warm air, it will tend to drain away, flowing downhill.

In dual courtyard design, a shaded, spray-cooled courtyard provides a cool ventilation air supply, while the heat trapping effect of a sunny courtyard on the other side of the unit propels an upward flow of warmed air, drawing the cool air through the house.

Spray-mist type area “fogger” can cool a large air mass instantly and benefit the plants as well.


INFERENCE:

Bioclimatic design is based on analysis of the climate and ambient energy represented by sun, wind, temperature and humidity.

REFRENCE:

Milne, murray.1997. Energy Design Tools.Web page, department of architecture and urban design.University of California los Angeles (UCLA)www.google.comhttp://www.aud.ucla.edu/energy-design-toolswww.solearth.comwww.slideshare.com


http://www.google.com/




http://www.aud.ucla.edu/energy-design-tools

http://www.solearth.com/

http://www.slideshare.com/

bioclimatic design at the site planning scale

Education