ENVIRONMENTAL ASPECTS IN WARM AND HUMID CLIMATE

ENVIRONMENTAL ASPECTS IN WARM AND HUMID CLIMATE

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Interpret environmental influences on the human comfort and building services system design in warm and humid climateLearning Outcomes 2

Students would be able to:

Explain the building planning related to :a. external spacesb. walls and roofsc. air flow and openingsd. Ventilation

Sun radiationAir movementTemperatureRain

Climate influences on building planning - External spacesRoof design and materials can reduce the amount of air conditioning required in hot climates by increasing the amount of solar heat that is reflected, rather than absorbed, by the roof. Proper insulation is also important in attics and building cavities adjacent to the roof.Solar photovoltaic (PV) systems can either be installed as a rooftop array on top of the building or a building-integrated photovoltaic system can be integrated into the building as roofing tiles or shinglesClimate influences on building planning Roof design

Types of roof

Influenced by both design and materials. Design considerations:The placement of windows and doors.The size and location of which can be optimized to reduce energy losses. Importantly, material selection and wall insulation can both affect the buildings thermal properties.Climate influences on building planning Wall design

Climate influences on building planning Air Flow & OpeningClimate influences on building planning Ventilation

Determine the effects of the climate physical parameters to exposed structure of a building below:a. Windb. Precipitationc. Rainwater run offd. Moisture movemente. Temperature and solar radiationThe design starting point is the outdoor climate - how can the house modify the ambient conditions, so that indoors is always more comfortable than outdoors?

Climate and Building DesignEffects of the climate physical parameters to exposed structure of a building - Wind

Horizontal movement of the air is known as wind. This convection process causes changes in the air density, and those variations cause winds.Wind shear is encountered in an area where two winds moving in opposite directions "rub" or mix together. This shear zone creates small eddies and whirling masses of air that move in various directions. This generates tremendous turbulence

How does wind form?

13Effects of the climate physical parameters to exposed structure of a building - Precipitation

Effects of the climate physical parameters to exposed structure of a building - Rain water run offStorm drain runoff is robbing us of much of our freshwater sources

Rising Damp the inevitable rise of moisture through masonry.

Effects of the climate physical parameters to exposed structure of a building - Moisture movement

Moisture in buildings is a major contributor to mold growth, unhealthy buildings, and poorindoor air quality. Wetting of building walls and rainwater leaks are major causes of water infiltration, but so is excessive indoor moisture generation.

Solution

Effects of the climate physical parameters to exposed structure of a building - temperature & solar radiation21Air TemperatureHeat from the sun will increase the air temperature in the building through conduction, convection and radiation.Shelters and insulation materials are placed to the building to block the heat into the buildings.The best shelters are able to protect all walls from any increases of air temperature, reduce the negative impact to the wall surfaces and rotting of finishes surfaces.

22SUN RADIATION

Direct sunlight/sun radiation has a luminous efficacy of about 93 lumens per watt of radiant flux, which includes infrared, visible, and ultraviolet light.

Bright sunlight provides luminance of approximately 100,000 lux or lumens per square meter at the Earth's surface

Planning the design characteristic such as arrangement and building orientation is important in reducing the building exposure to heat from sunlight.

23TBTB

Malaysia is in warm and humid climate has a specific design guide. It follows the main east and west axis in placing any buildings (especially tall buildings)With good orientation the need for auxiliary heating and cooling is reduced, resulting in lower energy bills and reduced greenhouse emissions.24Understand the used of shelters to protect buildings/space from the Climate parameters stated above.2.3.1 Identify the types of shelters.2.3.2 Compare the modern shelters and the traditional shelters.2.3.3 Describe the effects of shelters in moderating temperature in a building.Easier- A shelter is a place that covers, protects, and provides safety - shield them from extremes of cold and heat, as well as from rain, snow, and wind.Harder- A human shelter is a structure or a natural feature that provides protection against bad weather, danger, or insect pests. The types of shelters people erect depend mainly on the climate, the materials that are available, and their intended use.

TRADITIONAL SHELTERTraditional shelters using nature to ventilate their house especially during hot seasons.The used of big trees around the house will help to cool the breeze into the house.The elevated floor and veranda in the kampong house will create the air circulation that will reduce the usage of electricity.

For existing structures, trees and hills can be used to minimize direct sun light. This green practice will lower cooling costs during hot weather!

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MODERN SHELTERModern and flexible structure Uses of awning, curtain, double glaze window etcAll these materials will absorb and block the heat from entering the buildingIt also will reduce glareIt will increase ventilation in the buildingMODERN SHELTER

MODERN SHELTERVENTILATION

Purpose of ventilation are: (a) to provide fresh air supply ( 12 m3 per person per day)(b) to dilute body odors and dilute acceptable level of carbon dioxide (c) to create a comfortable environmentThe function of a ventilation system is to supply fresh air in the right amount into the living space. The solution are mechanical ventilation system and natural ventilation system.33

Natural ventilationThe process of supplying and removingairthrough an indoor space without using mechanical systems. The flow of external air to an indoor space as a result of pressure or temperature differences. There are two types of naturalventilationoccurring in buildings:wind driven ventilationbuoyancy-driven ventilationWind driven ventilation depends on wind behavior, on the interactions with the building envelope and on openings or other air exchange devices such as inlets or chimneysLimitations of wind driven ventilation:Unpredictability and difficulties due to speed and direction variationsThequality of airit introduces in buildings may be pollutedMay create a strong draught, discomfort.34

mechanical ventilation system\

The determining factors the quality of ventilation system.Ventilation for health.

Provide ample O2 for breathing, cooking activities and etc.Prevent the high increase of CO2 and bad smell.Remove of the stale and humid air from toilets, kitchens and etc. Ventilation for thermal comfort

Provide the comfortable environment.Increase the heat loss through convection.Speed the process of evaporation.Wind velocity is important to determine the quality of air exchange in a room.Ventilation for structure cooling.The temperature difference (inside & outside) is influenced by the surfaces color and thermal capacity .The fresh air from outside is forced into the room and remove the hot air out of the room. This convection process will maintain the cool and comfortable air inside the building which in the end will cool the building structures.36Ventilation StandardsASHRAE (American Society of Heating, Refrigeration and Air-Conditioning Engineers) recommends for natural ventilation, the air movement of 0.1 0.3 m/s (1.5 2.5 ach) for domestic, 1.5 2.5 ach for office, with air conditioner >3 ach.

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Methods of Ventilation

Passive ventilationWind Pressure EffectStack effect

Mechanical ventilationFan & ventilation fanAC

Wind pressure EffectThe building design involves the determination of size and component of openings such as windows, chimney, louvers and air vent.Factor that influence the wind movement in buildings.OrientationOutside obstructionsCross ventilationSize and location of the openings.Opening control38

Factors that influence the wind movement in buildings.Size and location of the openings

Higher windows : The wind movement is upward.Center position : The wind movement covers the living zone.Opening ControlWind movement in the room is influenced by the projection of the outdoor & indoor shelters.The wind movement is upward.The wind movement is distributed throughout the roomThe wind movement is downward.39c. Orientation i. Wind direction (oblique - 45)- Able to increase the wind speed- Wind distribution is even.9045ii. Distance between buildings (5X the height)5HHThe wind is blocked cause the area between buildings is not well ventilated.The distance allows the wind to gain its speed back. The wind distribution is even.40d. Outside obstructions.The wind velocity increases when there is a tunnel effect.d. Cross VentilationIf there is any walls/object the wind movement in the room, the cross ventilation will not happen. Sekiranya tiada bukaan keluar @ terdapat sekakatan yang penuh, aliran angin tidak akan terbentuk. Oleh itu bukaan keluar perlu.No opening for the air to move out.The walls inside a room will block the from going into the other room.41The wind direction entering a buildingd. Cross ventilation (cont.)The cross ventilation is the most efficient passive /natural ventilation. Projection of an outdoor shelters will increase the wind velocity into a building.If the shelter is placed right on the window the wind direction in up ward and it not profitable.An opening between the shelters and the wall will able to equalize the air pressure.Louvers is good in directing the wind according to the angle of the window placed by dwellers.42The influence of environment to building forms/shapes.Building placing factors.Shapes & Building PlanningNoise problems.Lighting factors.sick building syndromeThe Factor of building placing.Geographical Factor.EarthTypes of earth.Under ground & surface water irrigation. Types of plants on top. TopographyTopography & slopes (water puddles at slopes moderate the temperature)Building design & relationship with earth axis.Irrigation at site.Climate at site. (wind, temperature and sun)Increase of 300-400m in altitude , the temperature change 1FPlantsTypes and location of the plants.Sound distributions. 43b. Climate FactorsSunNatural source of heat and light energy.

WindIndoor & outdoor ventilation.Shear load to the building structures.Wind infiltration cause the increase and loss of heat.

RainInfluence the roof design.Water at the site. effect the irrigation on site.Steep slope fast current.Moderate slope smooth and easy current. Flat roof need drainage on the roof.c. Sense factors.1. SceneryHelp in determining the faade of the building. Determine the location of the opening.Types of plants for the landscape.Absorb heat Promotes evaporationStrengthen the earth/soil structure.SoundSound level, quality and source influence the building faade and direction.Building materials choices and its installation.Types of sound control.Plants.Earth. Sound barrier walls.44b. Shapes and building planning.- Outdoor spaces.Shelters (plants & structures)Free wind movement between buildings.

- Walls and roofsBuild from low thermal load and light materials.Outside surface has heat and light reflectors.Double layered roof ( space at the roof as ventilation area.)Ceiling top has reflector.Apply a good resistant insulators.Use slope and wavy roof materials.

- Air movement and opening space.Size of the opening is suitable to the wind movement.Free from the effect of outdoor barrier. Air movement should not pass through hot area before reaching the building.Need mechanical ventilation.Raised house level.

- VentilationAir exchange rate is suitable.Air movement covers the living zone.Roof and ceiling ventilation ( Temperature difference - 2C)45Noise problems.NoiseIt is unwanted sound.The effect of noise is influence by the following factors:Exposure timeFrequency of exposureSound source distanceIncident timeExposed individual behavior.Unit is in dBSound source should be considered in building design and room layout design.

Source of noiseroads & highwaysrailwaysAirportHeavy industrial area.Building services equipments.

Characteristic of physical barriers to control noise.Strong and hard - to avoid from vibration and reverberation. Enough density to block and absorb the sound wave.Cavity resonance block walls are good in reducing noise.

46Understand the Sick Building Syndrome (SBS)2.4.1 Define condensation process in buildings.2.4.2 Discuss the effects of condensation in the building.2.4.3 Define SBS2.4.4 Describe the causes of SBS and their effect on the building and its occupants.2.4.5 Explain the methods to solve SBS problems.DefinitionThe surrounding condition in buildings which causing workers are uncomfortable, lack of concentration and reduce work performances.

Causes of SBSLack of fresh air and sun radiation.Lack of air movement Lack of ample lighting (natural/mechanical lighting)Bad air filtration.Lack of maintenance to the ventilation system.Source of fresh air location.Biological/chemical contaminants

SymptomsHeadacheLethargicEffect to eyes/nose 7 throat.Effect to esophagus Lack of concentration

e. Sick Building Syndrome

48SICK BUILDING SYNDROME (SBS)When there are 20% of the occupants have symptoms of SBS caused by the quality of air.

BUILDING RELATED ILLNESS (BRI)BRI is used when there are symptoms caused by air pollution identified in the building.Usually the symptoms show serious effect to human after tested clinically by laboratories.

49Solution to SBSGet rid off the source of pollutions.Increase the air exchange rate Clean the air filter Education & Communication.