integrated science m4 ventilation methods

VENTILATION Module 4 Unit 1 Lesson 4Integrated Science

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REVIEW QUIZREVIEW QUIZ

INTRODUCTIONINTRODUCTION

OBJECTIVESOBJECTIVES

Causes/Effects of air pollution


What is Ventilation?


Mechanical VentilationMechanical Ventilation

Natural/Passive ventilation


Ventilation features of our houses


OVERVIEWOVERVIEW

Ventilation is the final topic in this unit which has looked at: methods of heat transfer, appliances that use heat transfer to work; the effect of temperature on our body and the process of evaporation of heat from the body by sweating.

This slide presentation reviews sources of air pollution, including indoor thermal pollution which affects the indoor air quality, thus necessitating various methods of ventilation.

You can access various subtopics in the Menu on the LEFT of the first slide.

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NOTE: For some activities, you will be asked to type your responses in boxes. To do so, you must be in Slide Show View. You can insert and delete text in the box in Slide Show View.














In Term 1, you learned about various sources of air pollutants, whose effects make ventilation of buildings necessary.

This is a teaching slide set that will give you all of the content on types of mechanical and natural ventilation equipment and strategies. The activities will help you to better understand how the use of the various ventilation methods can prevent air pollutants, heat and moisture, from remaining indoors because they affect the indoor air quality, and can cause ill health and discomfort.

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OBJECTIVES OBJECTIVES

On completing this slide presentation, you should be able to: recall and identify sources of indoor air pollution.define ventilation and state its importance.describe mechanisms to ensure proper passive ventilation in buildings.virtually observe and assess good/bad ventilation features in Jamaican houses.begin to appreciate the good structures of the habitats in which they reside.search for information and share ideas.

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1: 1: Causes/Effects of air pollution – Causes/Effects of air pollution – Activity 1.1 : Pollutants inside our Activity 1.1 : Pollutants inside our houseshouses

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Question 1. Examine the diagram below and discuss within your group the likely effects of the pollutants shown, on the comfort within a house and on the health of people who might inhabit the house.













1: 1: Causes/Effects of air pollution – Causes/Effects of air pollution – Activity 1.1 : Pollutants inside our Activity 1.1 : Pollutants inside our houseshouses

Question 2. What might be other sources of air pollutants in our houses that are not shown in the diagram on the previous slide?

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CHECK













1: 1: Causes/Effects of air pollution – Causes/Effects of air pollution – Activity 1 .1– Pollutants in housesActivity 1 .1– Pollutants in houses

Feedback to Question 2:

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When you sneeze or cough into the air, viruses that cause, colds, ‘flu etc. are spread through the air as droplets and pollute the indoor air spaces. In some households in Jamaica, air pollution is generated by cooking with solid fuels in poorly ventilated places. Constantly burning rubbish pollutes both the outdoor and indoor air. (World Health Organization, 2006)

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1: 1: Causes/Effects of air pollution – Causes/Effects of air pollution – Recalling the effects of humidityRecalling the effects of humidity

Think back to what was discussed in a previous lesson about humidity and relative humidity.

How hot and sweaty we feel, especially within buildings, is a function of heat, humidity and air movement.

Remember …. Humidity is defined as the amount of moisture in the air. Relative humidity of the air affects how comfortable we feel. It is “ a percentage showing how much water vapour is currently trapped in the air relative to/compared to the maximum amount of water vapour the air can hold at a given temperature.”

Listen to this song ‘Humidity’ to remind yourself > http://www.youtube.com/watch?v=-vFg8l3aLe8

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As the relative humidity of air in a space – especially an indoor space - gets higher, it’s moisture-absorbing/holding capacity decreases.

This slows down or stops further evaporation of sweat from our skin into the air. So, the cooling effect that evaporation would normally produce for our bodies also decreases or ceases all together.

In short, higher humidity indoors causes us to feel hotter as we lose our ability to cool ourselves since no sweat evaporates from our skin. The air is humid and stagnant and we feel sweaty and uncomfortable.

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In contrast to that …. Low relative humidity means the air is dry and could hold a lot more moisture at that temperature. So, sweating occurs.

Because of its drying effects, low humidity in a building:

Can cause dry and itchy skin and mucous membranes, dry nostrils and sinuses, cracked or chapped lips, bloody noses, dry coughs and a dry sore throat, other cold symptoms and respiratory discomforts.

Makes it seem colder than it actually is. Increases static electricity.

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1: 1: Causes/Effects of air pollution – Causes/Effects of air pollution – What is air pollution?What is air pollution?

“Air pollution occurs when the air contains gases, dust, fumes or odour in harmful amounts” – i.e., amounts which “when present in sufficient concentration, for a sufficient time, and under certain conditions, tend to interfere with human comfort,” and which “could be harmful to the health or comfort of humans and animals or which could cause damage to plants and materials.”

The main reason for needing unpolluted air is: To get ‘fresh air’ into our lungs for respiration, in order to release energy needed for metabolism.

The main reason for a lack of ‘fresh air’ that causes indoor air pollution is poor ventilation.

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2: What is ventilation?2: What is ventilation?

The 'fresh air' that we need to inhale regularly should have little or no pathogens, the normal atmospheric O2 and CO2

concentration, suitable humidity, little or no pollutants.

When there is poor ventilation, air becomes stagnant with CO2, pollutants settle in the space, and heat and water vapour accumulate causing thermal discomfort and giving poor indoor air quality (IAQ). Read the content at > http://www.betterairnow.com/impofcleanair.aspx

So -- proper ventilation is needed always!

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Ventilation is the process of helping ‘fresh’ air to circulate throughout a building and removing stagnant and

polluted air at the same time.













2: What is ventilation?2: What is ventilation?

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Moist air

We need good ventilation to…Speed up evaporation of sweat from the body surface by moving the moist air away from the person. Remove moisture to outside of the room.Transfer heat to the outside.Ventilation is carried out by:

a.mechanical devices and

b.using natural methods.













3: Mechanical Ventilation3: Mechanical Ventilation

Mechanical ventilation utilizes equipment such as air conditioners, de/humidifiers, fans and hoods. These extract heat and moisture, thus changing the humidity, and they also circulate air through the building.

We refer to their use as ‘active ventilation’.

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Most often, their use is in kitchens and bath-rooms where a lot of moisture or vapour is generated; they have to be vented or opened to the outside.

Hood (over stove) used to vent air from a kitchen













3: Mechanical Ventilation - Fans3: Mechanical Ventilation - Fans

The most common mechanical ventilation device that people use is an electric fan. Why are fans so commonly used?? Well, a fan can be quite easily installed and used when natural ventilation is inadequate, or when rapid removal of odours, other air pollutants or of moisture to lower the humidity, is required.

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1. Now, think about what you’ve already learned about what conditions make us feel so hot, sweaty and uncomfortable. Write what a fan does to help with ventilation and to lesson our discomfort, then check it as you continue reading the next slides.














For effective room ventilation, a box fan can be placed into/in front of an open window with the fan blowing air into the room, to pull cooler air from outside into the room.

Watch up to 0.32 from > http://www.youtube.com/watch?v=BELOgxbuJyA

Interior doors should be opened, to enable the incoming, cooler air to flow through from one room to other rooms in the house.

See the diagram on the next slide.

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3: Mechanical Ventilation – Fans moving 3: Mechanical Ventilation – Fans moving airair

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A second fan should be placed in/in front of another window, to blow hot air out of the house.

Fan #2

Fan #1

This creates natural siphoning off of hot air throughout the house and it exits through high wall vents.













3: Mechanical Ventilation – Ceiling Fans3: Mechanical Ventilation – Ceiling Fans

Because the temperature in a room varies in layers, with the warmest air near the ceiling and the coldest air near the floor, a ceiling fan is useful for room ventilation purposes. As the fan blades turn, (Green arrow) they push air (Blue arrows) downward, towards the floor creating a downdraft, keeping the air circulating throughout the room and making the room feel much cooler. They create a kind of ‘artificial breeze’ that makes you cooler. Look at the path of air shown in this diagram.

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You’ve learned that, as humidity decreases, air density increases. The greater the air density, the more air will be moved by a fan spinning at a constant rate. So, as the humidity goes down, fans are more effective!

And, as you also learned, the more air moving across our skin, the easier it is for our sweat to evaporate and cool us. So, a room cooling via a reduction in humidity will feel extra cool because of increased air flow which improves our body’s cooling ability.

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3: Mechanical ventilation - Dehumidifiers3: Mechanical ventilation - Dehumidifiers

Earlier, we recalled that high humidity stops the evaporation of sweat making us uncomfortable.

A dehumidifier reduces the level of humidity in the air, especially in enclosed spaces.

It does this by using a fan to pull in warm air, running it over cold coils so it condenses into a liquid; the condensation that forms on the coil inside the dehumidifier is removed via a drain pipe or collected in a special reservoir, which can be emptied periodically. The dry air is reheated as it passes over a warm coil, and then warm air is discharged back into the room.

Watch > http://www.youtube.com/watch?v=_A87ys-eFV0

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3: Mechanical ventilation – What is a 3: Mechanical ventilation – What is a humidifier?humidifier?

Especially in cold, dry weather, the drying effects of low humidity can cause skin and respiratory discomforts. A humidifier can prevent such effects.

Humidifiers are devices that emit water vapour or steam to increase the amount of water vapour/moisture levels, i.e. humidity, in the air The air moistened by a humidifier is more comfortable to breathe.

Read > http://www.healthline.com/health/humidifiers-and-health#Uses2

And, look at the video at > http://home.howstuffworks.com/36090-gimme-shelter-how-humidifiers-work-video.htm

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3: Mechanical ventilation - Air 3: Mechanical ventilation - Air conditionersconditioners

Air conditioners are used especially during the summer, in offices, cinema houses and large buildings occupied by many persons.

Air conditioners (ACs) both cool the air and also remove moisture so you feel less hot and sticky. By removing moisture, ACs essentially act like dehumidifiers.

Watch these videos and make notes from > http://www.youtube.com/watch?v=1MiQCBIx1mM

Also http://www.youtube.com/watch?v=_lFUlA1PZ8U

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4: Natural/Passive Ventilation4: Natural/Passive Ventilation

Natural ventilation methods are said to be passive, because the strategies use various building features and air temperature and pressure differences inside and outside to move hot and cold air, rather than relying on equipment or machinery to manipulate the sun’s heat and the wind for ventilation.

Natural ventilation strategies involve: the intentional inflow of air through

the use of windows, vents, doors and other openings in buildings;

the outflow of air from indoor spaces to the outdoors.

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4: Natural Ventilation – Features/Devices 4: Natural Ventilation – Features/Devices usedused

So the placement and orientation of the building and the use of vegetation outside form one important set of strategies.

Use of windows, doors and other types of openings and vents are the most commonly used strategies, because they allow both cross ventilation and stack effect ventilation to remove heat and moisture. The right placement of these openings as well as their size is an important consideration to ensure they work well.

These strategies are often not as effective at removing moisture, so a combination of the mechanical and natural ventilation methods is frequently used.

Watch/listen to this video, pausing it when necessary, to note the range of passive ventilation methods the narrator identifies > ttp://www.youtube.com/watch?v=IvCI3Q_5A8Y

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4: Natural/Passive ventilation – Activity 4: Natural/Passive ventilation – Activity 4.1 4.1

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1. Look at the old Barbadian chattel house (right), raised high off the ground. What other natural ventilation features can you identify on it?

Click for possible answers

Buildings can be raised on ‘stilts’ – so cool air can circulate all around it. It is a feature of older houses!













4: Natural/Passive ventilation – Activity 4: Natural/Passive ventilation – Activity 4.1 4.1 Feedback to Activity Question 1Feedback to Activity Question 1

Feedback to Question 1: What other natural ventilation features can you identify in this old Barbadian chattel house?

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From long ago, natural ventilation features were being built into houses, such as raising them high off the ground for air circulation. How many of these ventilation features did you actually notice in the Barbadian chattel house?• Gabled roof and gable end vents high up under the eaves.• Several windows, each with a sun-shade over it.• Both sides of the door that can be opened for passage of air. • Vegetation around house.Have you ever seen similar features in old Jamaican houses?

Chattel houses were not built on solid foundations. They were just placed on stilts – large stones, bricks or wood - so that they could be easily disassembled and moved if the owners had to go to work on other sugar estates. But, being high up off the ground also served the function of ventilation – allowing air to circulate all around the house.

DID YOU KNOW? DID YOU KNOW?













4: Natural/Passive ventilation – Activity 4: Natural/Passive ventilation – Activity 4.14.1

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2. What natural ventilation features can you identify in this house photograph?

Click for possible answers













4: Natural/Passive ventilation – Activity 4: Natural/Passive ventilation – Activity 4.1 4.1 Feedback to Activity Question 2Feedback to Activity Question 2

Feedback to Question 2: What natural ventilation features can you identify in this house photograph?

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How many of these did you actually identify?•Several large/wide and high windows and also several doors.• Many windows on several sides of the house.• Gabled roof (See diagram – shown).• Gable end vents high up under the eaves.• Roof overhanging windows/doors.• Windows have shades over them.• Light-coloured exterior walls.• Vegetation around the house.

Now, go through the next slides to learn why these features provide good, natural ventilation.













4: Natural/Passive ventilation - Methods 4: Natural/Passive ventilation - Methods usedused

The most commonly used passive ventilation methods are openings – windows, doors, vents, transoms. This is because they allow us to control and manipulate the passage of heat and wind into, through and out of our buildings, by their number, size, placement in the building and structure.

Especially when they are used with a well designed house, they can provide all the ventilation that might be needed.

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1. Look at the house designs and placements of the openings on the next set of slides. Note the arrows that show air movement.













4: Natural/passive ventilation methods – 4: Natural/passive ventilation methods – Activity 4.2: Room designs and windows Activity 4.2: Room designs and windows

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2. Discuss these two diagrams. Why do you think the top house has a better ventilation design than the lower one?

Click for possible answers.













4: Natural/passive ventilation methods – 4: Natural/passive ventilation methods – Activity 4.2: Room designs and windowsActivity 4.2: Room designs and windows

Feedback to question: 2. Why do you think the top house has a better ventilation design than the lower one?Note that in the house in the top (Blue) diagram, that design of single room depths provide “optimal cross-ventilation because each room has opposite exit and entry points (windows/openings) for the breezes to pass through.” The lower diagram (Pink) shows that “a poorly designed home with internal walls and barriers to cross-ventilation will have stagnant, stuffy hot-spots that may need exhaust fans.”

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4: Natural/passive ventilation methods – 4: Natural/passive ventilation methods – Activity 4.2: Room designs and openings Activity 4.2: Room designs and openings

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3. In which room would you infer there is good air circulation and ventilation? Left or Right?

Feedback to Question 3: The left room has poor ventilation because there is no outlet for air, which stagnates in the room. The right room has good ventilation. Why? Because hot air can rise and exit via the roof vent and cause cool air to be pulled in via lower window/s. Note also that the house is close to a tree which provides shade and air movement.

Click here for possible answers.

Left Right













4: Natural/passive ventilation methods - 4: Natural/passive ventilation methods - Window placementWindow placement

When windows are being used…Make the area of the windows as tall and as wide as possible.Use, ideally, both sliding glass and fine mesh screen panels, to maximize air flow when windows are fully open, yet at the same time preventing insects (e.g. especially house flies, cockroaches and mosquitoes) from entering.Place few/no windows on East and West -- this prevent rays of the rising/setting sun entering room as earth rotates.

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4: Natural/passive ventilation methods –4: Natural/passive ventilation methods –Placing windows for breeze & to reduce Placing windows for breeze & to reduce sunlightsunlight

Place most windows on North and South walls or on as many opposite walls as possible, so breezes can blow through and the slightest breeze or air movement will facilitate cross ventilation – i.e. the breeze can go in one wall and out of the opposite wall.

Assign rooms for daytime/nighttime activities to take advantage of the path of sunlight across the house, from sunrise to sunset.

Check the next slide!

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4: Natural/passive ventilation methods - 4: Natural/passive ventilation methods - Position of windows for cross ventilationPosition of windows for cross ventilation

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Arrows show direction of air movement for cross ventilation













4: Natural/passive ventilation methods – 4: Natural/passive ventilation methods – Position of windowsPosition of windows

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Arrows show direction of air movement for cross ventilation

Gable roof Gable end vent













4: Natural/passive ventilation methods4: Natural/passive ventilation methods

High gabled roofs are good for getting rid of hot, stale and possibly polluted air, as hot air is less dense and lighter so tends to rise, and….

Gable end vents below a gabled roof, placed high above the windows under the protection of the eaves - so the stale air, which is hot and light, can rise then exit the room through gable vents. See picture on next slide, 39.

Placing small, fixed louvers and transoms above windows/doors - serve the same function of removing heat and stale air.

Look at some of these on the next slide, #41.

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4: Natural/passive ventilation methods – 4: Natural/passive ventilation methods – Openings for natural ventilationOpenings for natural ventilation

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A transom, is a small, detail window over a door or, sometimes, above another window. It is called a ‘fanlight’ if it has a semi-elliptical shape like a flared- open hand-fan,

A gable end vent helps heat to escape and helps keep condensation from forming on surfaces.













4: Natural ventilation methods –4: Natural ventilation methods – Stack effect ventilation Stack effect ventilation

In tall/high spaces, placement of openings at varying heights allow vertical stack effect ventilation, especially when there is a temperature difference between the inside space (warmer) and the outdoors (colder).

Windows must be lower so that the heavier cool/cold air from outside enters the building, then, as it heats up, from people’s activities, air becomes lighter and rises, moving on convection currents.

The other openings higher up – e.g. vents, transoms, air towers – are the exit points for this hot, light air which is now hotter than the outside air. So the heated air exits the building.

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4: Natural ventilation methods – Position 4: Natural ventilation methods – Position of openings of openings

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Arrows show direction of air movement for stack effect ventilation in tall buildings













4: Natural/passive ventilation - – 4: Natural/passive ventilation - – Manipulating heat Manipulating heat

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A central courtyard allows hot air to be channeled up and away from the building while, at the same time, cool air

enters to replace hot air.













5: Ventilation features of our houses –5: Ventilation features of our houses – Career Focus Career Focus

Who are the persons that either design, construct or install ventilation devices in our buildings? First, of course, are architects who design the buildings!

Get a brief introduction to Jamaican architect – Michael Lorde, at > http://www.csa-utech.com/faculty_details.php?Lorde-16

Another person is the contractor and his/her team of masons, plumbers, carpenters, who construct the buildings according to the blue print plan, making sure that all the natural ventilation structures/devices are correctly built and/or installed.

Technicians/ electricians install mechanical ventilation devices e.g. extractor fans, AC units, hoods etc.

There’s a whole range of jobs from which you could have a satisfying, rewarding career, including being a Researcher who develops and tests new flooring, roofing, wall materials and types of window glass for buildings.

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REVIEW and QUIZREVIEW and QUIZ

Are you ready to test yourself? There are Short-answer questions and

TRUE/FALSE questions that you are required to do.

For each of the latter questions, click on the word ‘TRUE’ or ‘FALSE’, check the Feedback, then click the button ‘NEXT QUESTION’ to continue.

Click the BEGIN QUIZ button to start the quiz.

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BEGIN QUIZ













Short-answer QuestionsShort-answer Questions

1. 1. What are natural methods of ventilation?

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Feedback -1 : Natural ventilation methods utilize placement/size of windows, doors, vents and other openings; location and size of the building; landscaping; type and structure of roof; building design.

2. Name the usual mechanical ventilation devices used in large buildings.

Feedback - 2: Air conditioners, humidifiers, fans, hoods in kitchens, extractor fans in bathrooms, kitchens and damp areas.

Click here for check your answer to Question 1

Click here for check your answer to Question 2













TRUE/FALSE QuestionsTRUE/FALSE QuestionsClick True or False.

1. In ventilating a dwelling, these two elements are manipulated for natural cooling.

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TRUE

FALSE

The SUN’s HEAT

The WIND

Click True or False.














2. Providing openings for breeze to flow through and move away vapour, creates drier air within an enclosed building (up to a point) and that improves the comfort level of occupants.

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3. These windows are placed for cross ventilation.

TRUE FALSE

TRUE FALSE














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5. In warm or humid months, in tropical climates, maintaining thermal comfort can only be done by using humidifiers.

4. All of these pictures show structures used for mechanical ventilation.L – R = extractor fan, window, stove hood

FALSETRUE

FALSETRUE













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6. Thermal comfort is effected by heat conduction, convection and radiation and also evaporative heat loss.

TRUE FALSE

TRUE FALSE

5. Maintaining thermal comfort for occupants of houses or other enclosed buildings is one of the important goals of ventilation.

TRUE/FALSE TRUE/FALSE QuestionsQuestionsClick True or False.













End of ActivityEnd of Activity

You have reached the end of the content and the activities.

If you wish to review any concepts in this lesson, go to the first slide and click the subtopic on the left.

If you have finished viewing the slides, click the Close (X) button.

Return to the ‘Closure’ section in your SIM.

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CREDITSCREDITS

http://www.thedailygreen.com/environmental-news/latest/indoor-air-quality-47020101#ixzz1sNSe359g http://www.getasthmahelp.org/indoor-air-quality.aspx http://www.builderbill-diy-help.com/tropical-building.html http://www.sunstoneyoga.com/about/heat-humidity-youhttp://www.panoramio.com/photo/41246932 http://www.aedhotep.com/index.php?option=com_morfeoshow&task=view&gallery=7&Itemid=74 http://www.aedhotep.com/ http://en.wikipedia.org/wiki/File:Air_conditioning_unit-en.svg http://janderson99.hubpages.com/hub/Cross-Ventilation-in-House-designs-for-Natural-Passive-Air-Flow http://janderson99.hubpages.com/hub/Cross-Ventilation-in-House-designs-for-Natural-Passive-Air-Flow http://home.howstuffworks.com/humidifier1.htm http://www.youtube.com/watch?v=IvCI3Q_5A8Y http://www.youtube.com/watch?v=1MiQCBIx1mM http://www.youtube.com/watch?v=OphiN2y5w_A&feature=related http://home.howstuffworks.com/humidifier.htm http://home.howstuffworks.com/humidifier3.htm http://www.youtube.com/watch?v=IvCI3Q_5A8Y http://www.youtube.com/watch?v=VLwCqZmQpOg

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integrated science m4 ventilation methods

Education

houses ventilation features

goodbad ventilation

various methods of ventilation

various ventilation

natural ventilation

proper passive ventilation

indoor air quality

houses objectivesobjectives