IKLIM DAN BANGUNAN

Buildings and Climate

• Climate varies around the globe and indigenous architecture used to respond to climate

• 20th century buildings became exclusively dependent on mechanical systems to heat and cool buildings

• International Style Architecture, characterized by sealed buildings, tried to create an architectural style that ignored climate

• This has resulted in a proliferation of architecture that does not properly respond to its climate

• Such buildings now account for between 40% and 70% of energy use in North America – and this cannot be sustained given Climate Change (GHG) and fossil fuel shortages

• This lesson will examine how to reconnect issues of local climate and building design

A building’s primary function is to provide shelter from the elements, as a function of CLIMATE.To function as a moderator of the environment and to satisfy all other requirements, a building envelope must provide control of:1. heat flow2. air flow3. movement of water as

vapour and as liquid4. solar and other radiation

Environmental Moderator:

Urban Ecology Centre, Milwaukee

Designing to the Comfort Zone vs. Comfort Point:

This famous illustration is taken from “Design with Climate”, by Victor Olgyay, published in 1963.This is the finite point of expected comfort for 100% mechanical heating and cooling.To achieve CN, we

must work within the broader area AND DECREASE the “line” to 18C – point of calculation of heating degree days.

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Climate and primitive constructions

In hot-wet tropics: latitudes 10°-15° from equator, mainly developing countries, 40% population lives in the belt.

Small annual variation of temp, intense solar radiation, high humidity, and heavy rainfall.

House should provide maximum ventilation and shades, roofs must be waterproof, walls movable. House often stilted to prevent frequent flooding near rivers that connect to outside world (or catch sea breeze in island), movable shutters (or porous walls). Materials have little or no heat storage capacity.

In tropical deserts (40°C daytime, and 10-15°C at night), intense solar radiation and heat during the day and low temperatures at night.

Mud and straw are the basic materials. High heat capacity of these materials help maintain even temp in the building; thick walls with minimum window space. Grouped dwellings in dry area are often built close together for maximum shade (narrow streets in many Arab communities).

Valleys are parallel to prevailing winds (minimize wind exposure), shaded side walk, short walking distance, courtyard with greenery, compact geometry, use high albedo materials as building surfaces. Dense and substantial thickness walls release heat during night, block sun during day, indoor temp lag behind outdoor.

Polar region, Inuit Igloo: hemispheric shape minimizes hear loss by providing maximum volume with a minimum of surface area and effectively resists the strong Arctic wind

• Indoor temperature has smaller diurnal variations

• The maximum and minimum temperature occur later indoor

When we design WITH the specific local environmental characteristics in mind, we start to manipulate the relationship between the climate, the site and the building to create a local environment or MICROCLIMATE around the building.

This “mini climate” that is created around the building can decrease the apparent severity of the climate (and hence the work the building must do to make for a comfortable interior AND exterior environment around the building) OR, if badly handled, can increase the severity of the local climate.

Microclimate

St. Thomas University, Houston

Basic understanding of the 4 climate design zones tells us that certain building types obviously do not belong in certain places...

…but there are more aspects to consider...

…this does not belong here…

The building might be the same but the site/climate/microclimate conditions will drastically impact the success of the comfort experienced by the

occupants.

Original condition Hot Arid Site Hot Humid Site

Temperate Site Cold Site

Bio-climatic Design: COLDWhere winter is the dominant season and concerns for conserving heat predominate all other concerns. Heating degree days greatly exceed cooling degree days.

RULES:- First INSULATE- exceed CODE requirements (DOUBLE??)- minimize infiltration (build tight to reduce air changes)- Then INSOLATE and fenestrate for DIRECT GAIN- ORIENT AND SITE THE BUILDING PROPERLY FOR THE SUN- maximize south facing windows for easier control- apply THERMAL MASS inside the building envelope to store the FREE SOLAR HEAT - create a sheltered MICROCLIMATE to make it LESS cold

YMCA Environmental Learning Centre, Paradise Lake, Ontario

Bio-climatic Design: HOT-ARIDWhere very high summer temperatures with great fluctuation predominate with dry conditions throughout the year. Cooling degrees days greatly exceed heating degree days.

RULES:- Solar avoidance : keep DIRECT SOLAR GAIN out of the building- avoid daytime ventilation- promote nighttime flushing with cool evening air- achieve daylighting by reflectance and use of LIGHT non-heat absorbing colours- create a cooler MICROCLIMATE by using light / lightweight materials- respect the DIURNAL CYCLE- use heavy mass for walls and DO NOT INSULATE

Traditional House in Egypt

Bio-climatic Design: HOT-HUMID

Where warm to hot stable conditions predominate with high humidity throughout the year. Cooling degrees days greatly exceed heating degree days.

RULES:- SOLAR AVOIDANCE : large roofs with overhangs that shade walls and to allow windows open at all times- PROMOTE VENTILATION- USE LIGHTWEIGHT MATERIALS that do not hold heat and that will not promote condensation and dampness (mold/mildew)- eliminate basements and concrete- use STACK EFFECT to ventilate through high spaces- use of COURTYARDS and semi-enclosed outside spaces - use WATER FEATURES for cooling

House in Seaside, Florida

Bio-climatic Design: TEMPERATE

The summers are hot and humid, and the winters are cold. In much of the region the topography is generally flat, allowing cold winter winds to come in form the northwest and cool summer breezes to flow in from the southwest. The four seasons are almost equally long.

RULES:- BALANCE strategies between COLD and HOT-HUMID- maximize flexibility in order to be able to modify the envelope for varying climatic conditions- understand the natural benefits of SOLAR ANGLES that shade during the warm months and allow for heating during the cool months

IslandWood Residence, Seattle, WA

Whether you are sited in a city or suburban space makes a difference. Access to green space can keep the building cool. The “urban heat island effect” is caused by too much building, hot roofs, pavement, (aka thermal mass) and not enough greenery in cities. Tree cover is also important to keep the sun off of paved areas. The microclimate in urban centres can be very different from more natural sites.

Urban Heat Island Effect

Downtown Houston