Senior Form Physics – Sustainable Building
Sustainable Building
Teacher’s Version (with video exemplars)
NOS/STSE Features1. Science, technology, society and environment (STSE) are interconnected.
2. Technology can improve our quality of living, but it may also bring us adverse impacts.
3. Technology is driven by societal demand and human’s need.
You can click an icon like this to access the activities in this package.
You can click an icon like this to access the PowerPoint files in this package.
You can click an icon like this to access the exemplar videos in this package.
Icons of different colours indicate exemplars from different teachers.
Table of Contents
Introduction / / (i)Activity 1: Introduction to sustainable building / / P.1
Activity 2: Don’t heat me up! / / P.4
Activity 3: Investigating the energy efficiency of school & home / / P.9
Activity 4: Why sustainable building? / / P.12
Optional Activity: Design of sustainable buildings / / P.13
Appendix 1: Reference information for different types of glasses / / P.14
Appendix 2: Investigation Guide: Reference for Activity 2 / / P.17
Appendix 3: More information for U-value of materials / / P.19
Appendix 4: Reference for Activity 3 / / P.20
Appendix 5: Lesson plan / / P.22
© 2007 The University of Hong Kong – Faculty of Education. All rights reserved.
Senior Form Physics – Sustainable Building
Introduction
Rationale
In 1987, the then Prime Minister of Norway, Dr. Gro Harlem Brundtland created the landmark definition of Sustainable Development in The Brundtland Report:
“Development that meets the needs of the present without compromising the ability of future generations to meet their own needs.”
The evolution of “sustainable development”, which has been one of the most influential concepts of the late 20th century, shows that society’s demand for environmentally friendly and energy efficient products is growing. It leads to corresponding developments in science and technology. Sustainable buildings are an important example. Architects and building engineers minimize energy and resources use and provide a good internal environment without reducing building quality. In this teaching package, students will experience a hotbox test. This compares the thermal properties of different building materials. Students design an investigation to study the energy performance of their home and school buildings. The package further discusses the interrelationship between science, technology, society and the environment (STSE) through the topic “Sustainable Building”.
Level of study Number of lessons
Form 4 – Form 7 5 lessons (each lesson 35 – 40 minutes)
Contents
1. Concept of sustainable development and sustainable building
2. Essential features of a sustainable building
3. Hotbox test for comparing insulation capacity of different building materials
4. Properties of solar film, double-glazed glass and low-E glass
5. Knowledge of U-value and shading coefficient.
6. Designs and measures for improving energy performance of buildings
7. Investigation of energy performance of home and school buildings
8. STSE discussions on the topic of sustainable building
Teaching package includes
1. Worksheets (Teacher’s Version and Student’s Version)
2. Two Teaching PowerPoints
(i) © 2007 The University of Hong Kong – Faculty of Education. All rights reserved.
Senior Form Physics – Sustainable Building
/ Activity 1Introduction to sustainable building
Notes: Some books use the term “Green Building” while some use “Sustainable Building”. Though “Green building” is often regarded as a more popular and common term, virtually they mean the same thing.
The term “Sustainable Building” comes from “Sustainable Development”. In 1987, the Prime Minister of Norway, Dr. Gro Harlem Brundtland created the landmark definition of Sustainable Development in the Brundtland Report, “Our Common Future”
Q1.
Brainstorm some essential features of a sustainable building based on the landmark definition of “Sustainable Development” above, and what you may have learned through other aspects of environmental education.
Some possible answers:- Energy efficient
- Non-wasteful and non-polluting
e.g. minimize CO2 emission and Ozone depletion.
- Highly flexible and adaptable for long-term functionality
- Easy to operate and maintain
- Support the health of the occupants
- The buildings contain sustainable designs that will not exhaust the natural
resources of the world. (Response to Dr. Gro Harlem Brundtland’s message about
Sustainable Development to the world)
Notes: Teachers can discuss the ideas raised by students in terms of sustainability
Q.2
What are the different types of energy use in residential buildings and in commercial buildings in Hong Kong?
Among the uses of energy you mentioned, which consumes the largest amount of energy? You will look into it in Activity 2 – “Don’t heat me up!”
Notes: Refer to the charts in the teaching PowerPoint for larger views.Air conditioning consumes the largest proportion of energy
Air conditioning consumes the largest proportion of energy
Source: Electrical and Mechanical Services Department (EMSD), 2005
Q.3
The technology of air conditioning gives us a more comfortable environment during summer but it also brings us some negative impacts. Can you list some?
Some possible answers:- Increase energy consumption (combustion of fossil fuels)
- More emission of CO2
- Worsen global warming
Notes: Teachers can remind students of the recent campaigns which encourage people to set air-conditioned room temperature at 25.5°C in summer
Notes:
Students will investigate the designs and measures for improving the energy performance of a building in Activity 3: “Investigating the energy efficiency of the buildings around you”. Based on the context of sustainable building, students will discuss the relationship between science, technology, society and environment in Activity 4: “Why sustainable building?”
Don’t heat me up!
Engineers have to make sure buildings are comfortable to live in – not too hot in summer and not too cold in winter. To achieve this aim they use different kinds of building materials to reduce the heat transfer through conduction and radiation.
Quick revision: How is heat transferred? By which three processes?
Investigation: To find out whether single glass or double-glazed glass can better slow down the heat gain of indoor space by sunlight. Draw your design in the space below:
Teacher shows the design of the hot box test after students finish their designs.Compare the difference between the suggested designs and the students’ designs.
First round of hot box test (Single glass VS Double-glazed glass)
B - Single glass [20 mm thick]
Temperature (oC) at 30-second intervals
Time (seconds) / 0 / 30 / 60 / 90 / 120 / 150 / 180 / 210 / 240 / 270 / 300Double-glazed glass
Single glass
Q. What is the result of the demonstration? How can you explain the result?
Over 95% of the heat is transferred from the sun (the light bulb) to the indoor space (the temperature sensor) by radiation because both the single glass and double-glazed glass are transparent to solar radiation.
Second round of hot box test
(Glass with sun control film VS Low-e glass VS Clear glass)
A - Low-emission / Low-e glass [6 mm thick](coated with metallic oxide reflecting layer)
B - Glass coated with “3M” radiant energy blocking film (sun control film) [6 mm thick]
(solar films are used to reduce the heat gain of a building through radiation)
C - Clear glass [6 mm thick]
(ordinary glass with poor heat insulation properties)
Temperature (oC) at 30-second intervals
Time (seconds) / 0 / 30 / 60 / 90 / 120 / 150 / 180 / 210 / 240 / 270 / 300Low-emission glass
Glass with sun control film
Clear glass
Q. What properties of the sun control film and low-emission glass may account for the experimental results?
The metallic oxide layer in the low-emission glass can reflect some radiant energy / low wavelength radiation such as UV light. The sun control film can block the entry of radiation. These properties greatly reduce the amount of heat transferred by radiation through glass. Remarks: the advantage of low-emission glass over sun control film is that the visibility of low-emission glass is much higher than typical sun control film.Third round of hot box test
A - Ceramic tile [6 mm thick](common on walls of kitchens, bathrooms and exterior surfaces)
B - High-density polystyrene board [6 mm thick]
(a kind of very high density foam, a common component of roof structure)
C - Wooden board [6 mm thick]
(used as building materials in countries overseas)
d
Temperature (oC) at 30-second intervals
Time (seconds) / 0 / 30 / 60 / 90 / 120 / 150 / 180 / 210 / 240 / 270 / 300Polystyrene board
Ceramic tile
Wooden board
Q. What is the result of the demonstration? How can you explain the result?
Result: Temperature of the three materials rises very slowly, temperature of polystyrene board rises slightly faster then the other two.Reasons: Since the materials tested are not transparent / only slightly transparent to solar radiation, radiation cannot reach the other side of materials effectively. As a result, the temperature rises slowly.
Polystyrene is slightly transparent and allows small amount of solar radiation to pass through it. Thus, its temperature rises slightly faster than the other two.
Further discussions
The hot box test (with a much more complex setup) is commonly used in buildings research. Discuss the importance of the hot box test to the design of sustainable buildings.
Energy efficiency is an important issue in sustainable building. With the help of a hot box test, civil engineers can select building materials with good insulation and high capacity for blocking radiant energy, so that less electricity is needed for space (air) conditioning.U-value and shading coefficient are two common measurements in comparing the thermal properties of materials in industry:
U-value is a measure of heat transmission due to thermal conductivity (conduction + radiation + convection) of a material. The lower the U-value, the less heat is transmitted through the material.
(Refer to appendix 3 for more detailed information for U-value of materials)
Shading coefficient is the ratio of solar heat gain through a piece of special glass to the solar heat gain through a single piece of 3mm thick clear glass under the same set of conditions. The smaller the number, the better the special glass at stopping the entry of solar heat radiation.
Rank the materials tested in second round by their shading coefficients.
Glass with solar film < Low-E glass < Single clear glassOther special building materials: Fire-resistant glass
There are many types of specially made building materials and glasses serving for different needs of buildings. Fire-resistant glass: a kind of glass that is widely used in buildings for safety purpose. Can you think of some features of this type of glass that can enable it to have “fire-resistant” property?
Please refer to the second part of Appendix 1 for the details for the fire-resistant glass.Investigating the energy efficiency of your school building and home building
The use of carefully selected building materials is only one of the many ways to improve the energy efficiency of buildings. We will explore some other ways in this activity.
Let’s first go back in time to learn about the most ancient sustainable “building“before investigating the modern buildings around you.
Before building technology began, people used to live in caves – the most ancient sustainable “building”. Cave dwelling (穴居), as shown in the pictures below, provided prehistoric people with a “comfortable” and “safe” home.
What are the advantages of cave-dwelling?
In summer, the temperature inside the cave is lower than the temperature outside since sunlight cannot penetrate into the cave and the thickness of earth above it absorbs radiation (e.g. Wine caves in France remain at a constant 54°F.)
In winter, the temperature inside the cave is higher than outside because caves are made of rock which is a good heat insulator, thus the heat loss to surroundings is low. If the cave entrance is curved, the occupants can be shielded from cold winds.
In China, cave dwellings are mostly found in the North and located on mountains. Why?
One of the disadvantages of living in cave is the poor ventilation. As the humidity of the southern part of China is higher than the northern part, most cave dwellings are found in the North, especially on the mountains, where humidity is even lower. People living on mountain can also escape from attacks by wild animals.
Now come back to the modern age. Can you think of:
1) Designs of buildings that can help to improve energy conservation?
2) Ways that the occupants can help to increase energy conservation in modern buildings?
Design changes of buildings / Ways that occupants can help:If you only have a few ideas, you are recommended to download and read the Energy Efficiency and Conservation for Buildings Guide from the website of Electrical and Mechanical Services Department (EMSD)
URL: http://www.emsd.gov.hk/emsd/eng/pee/em.shtml
(Last visited on 30 – 05 – 2007)
This contains many suggestions for the builders (designs of the buildings) and occupants (ways they can help) to reduce energy use in a building.
Teachers can provide the students with the following keywords when necessary. These keywords can guide the students to read relevant parts in the EMSD booklet shown above.
Building orientation / Use of renewable energyNatural lighting / Building materials
Artificial lighting / Effect of plants
Shading devices / Space planning
Natural ventilation / Lifts
Air conditioning / Toilets (e.g. sensor controlled lighting)
Action! Notes: A PowerPoint of typical sustainable designs/features is
available for reference.
Part 1: Planning the investigation
Make a checklist based on the answers from the previous discussion with your groupmates. The checklist should consist of a list of energy efficiency features of buildings. Use it to investigate your school building and your home building. Evaluate the energy efficiency of these two buildings based on the results of your investigation and present the findings to your classmates.