THE HONG KONG POLYTECHNIC UNIVERSITY
Department of Building Services Engineering
Subject : Sustainability and the Built Environment (BSE5518)
Level : 5
Session : 2019/2020 Semester 1
Date : 7 January 2020
Time : 7:00 pm – 10:00 pm
Time Allowed : 3 hours
This question paper has 14 pages.
Instructions to Candidates:
1. This is an open book examination.
2. Answer any 3 questions out of 5.
3. Total attainable marks for the examination paper is 99.
4. All questions carry equal marks.
5. Graph paper is attached.
Recommended list of materials allowed to be taken into the examination venue:
1. Electronic calculator
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lbsys
Text Box
Programme : 04001-MSc-BSE/FM
1
Q1. (a) Using the data shown in Table Q1-1, plot a graph to show the profile of energy
consumption density vs population density for various world cities. Describe your
observations and explain what the possible reasons causing these observed
phenomena are.
Table Q1-1 Energy Consumption and Population Density for Various World
Cities
City Population Density
(person per acre)
Energy Consumption
Density (GJ/ha)
Houston 12.5 75
Phoenix 12.5 70
Detroit 18 66
Denver 18 63
Los Angeles 25 59
San Francisco 22.5 55
Washington DC 18 50
Chicago 20 57
New York 20 43
Perth 12.5 32
Toronto 40 33
Brisbane 12.5 30
Sydney 22.5 26
Frankfurt 50 16
Paris 27.5 10
Vienna 75 10
Singapore 82.5 5
Tokyo 102.5 8
Moscow 137.5 1
Hong Kong 270 2
(12 marks)
(b) Compare the population distribution patterns along a highway of the following two
towns in terms of their impacts on energy efficiency, provision of public
transportation and walkability (Assume that the total number of population around
the highway in Town A and Town B are the same).
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Figure Q1-1a Population distribution pattern around a highway in Town A
Figure Q1-1b Population distribution pattern around a highway in Town B
(9 marks)
(c) According to Professor Brendan Gleeson, vertical sprawl has become increasingly
observed in dense cities over the world. Explain what a vertical sprawl is. Discuss
what causes a vertical sprawl and what are its likely consequences on nearby
residents?
(6 marks)
(d) One of the proposals being put forward for mitigating the adverse impacts of
vertical sprawls is to incorporate greenery into external envelope design. Suggest
two alternative greenery forms that can be placed in the external envelope. Discuss
whether such proposal is a constructive solution and the underlying mechanism.
(6 marks)
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Q2.
Note: all the buildings shown are residential buildings with flats starting from
ground to top levels
Figure Q2-1 The existing building and street configuration
(a) Determine the aspect ratio of the existing configuration shown in Figure Q2-1.
(2 marks)
(b) Sketch the air flow patterns inside the road with configuration being shown in
Figure Q2-1. Explain the phenomena that are likely to be observed in the road.
Would it be any differences if the approaching wind was 0o instead?
(8 marks)
(c) Figure Q2-2 shows the carbon monoxide (CO) exposure values for the street
vendors, residents and pedestrians present on the road.
(i) What is meant by ‘CO exposure’?
(3 marks)
(ii) What will be the likely consequences for an individual exposed to a high CO
level?
(5 marks)
(iii) Predict the CO exposure levels of three population subgroups if trees were
planted on both sides of the footpaths. Briefly explain why.
(5 marks)
(iv) Predict the CO exposure levels of three population subgroups if the average
building height was 66m.
(3 marks)
(d) Comment on the thermal comfort and walkability in the road shown in Figure Q2-
1 during a hot and humid summer afternoon. Suggest two planning measures that
can effectively improve its walkability level and explain their underlying principles.
(7 marks)
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Figure Q2-2 Breakdowns of daily personal exposures to different types of
microenvironments for the three population subgroups when the
approaching wind is perpendicular
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Q3. (a) It has been commented that Lifecycle Analysis (LCA) can provide a more objective
and quantitative tool than eco-labels in the evaluation of environmental friendliness
of building materials. Explain what LCA and eco-labels are. Discuss whether you
agree to this statement.
(10 marks)
(b) Do you think it is appropriate to formulate mandatory requirements at this stage for
applying LCA to evaluate the environmental friendliness of materials used in
building construction? Briefly explain your answer.
(4 marks)
(c) Single impact point approach has been adopted in many LCA software for
evaluating and comparing the diversified impacts of various sustainable issues
caused by building materials. Examples of sustainable issues include global
warming, air pollution and ozone depletion.
(i) Suggest two other sustainable issues that you propose to be included in the
sustainable impact evaluation.
(3 marks)
(ii) Explain how the single impact point approach can be used to resolve the
challenges brought by a range diversified sustainable impacts caused by
different building materials?
(6 marks)
(d) Table Q3-1 shows the single impact points for all major building materials. Table
Q3-2 shows the weights of materials used in different elements of a commercial
building in Hong Kong. With aid of Tables Q3-1 and Q3-2, suggest one practical
measure that can significantly reduce the overall lifecycle impact for the building
interiors of a commercial buildings and evaluate its improvement.
(6 marks)
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Table Q3-1 Single lifecycle impact point values for different materials
Single Impact Point [Eco-indicator 99 (H) all / Europe EI 99 H/A] – Landfill
included
Aluminum 0.8660 pt/kg Concrete (Grade 45) 0.0832 pt/kg
Aluminum (60% Scrap) 0.3750 pt/kg Concrete (Grade 50) 0.0921 pt/kg
Aluminum (100% Scrap) 0.0476 pt/kg Concrete (Grade 60) 0.0972 pt/kg
Aluminum extruded 0.9000 pt/kg Cement Plaster 0.0897 pt/kg
Copper (30% Scrap) 2.0000 pt/kg Plaster White Finish 0.4550 pt/kg
Copper (from HQ scrap) 0.0764 pt/kg Slake Lime 0.3690 pt/kg
Copperwire (primary) 2.8700 pt/kg Gypsum 0.4630 pt/kg
Cast iron 0.0799 pt/kg Sand 0.0101 pt/kg
Steel (galvanized) 0.2970 pt/kg Gravel 0.0307 pt/kg
Steel Hot Rolled (rebar) 0.1620 pt/kg Stone 0.2520 pt/kg
Steel Stainless 0.4540 pt/kg Glass (Float – HQ) 0.2020 pt/kg
Construction (Structural) Steel 0.1560 pt/kg Glass (float) 0.1690 pt/kg
Board plywood meranti 0.3240 pt/kg Double glazed window 4.2500 pt/m2
Board plywood spruce 0.1170 pt/kg Glasswool 0.1870 pt/kg
Asphalt 0.0344 pt/kg Rock Wool 0.2180 pt/kg
Brick 0.0308 pt/kg PMMA sheet 0.6390 pt/kg
Cement 0.4090 pt/kg PVC Injection Molded 0.3030 pt/kg
Ceramics 0.2340 pt/kg PVC Pipe 0.2620 pt/kg
Concrete (Grade 35) 0.0745 pt/kg Wallpaint Acrylic 0.1540 pt/kg
Concrete (Grade 40) 0.0786 pt/kg Wallpaint Natural 0.1200 pt/kg
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Table Q3-2 Weights of materials used for different building interior
elements for a commercial building in Hong Kong
Element Classification Total weight (kg)
Ceiling Finishes Aluminum 16594.0
Glasswool 7236.0
Gypsum 18182.0
Plaster White Finish 63891.0
Rock Wool 5248.0
Steel (galvanized) 29650.0
Wallpaint Acrylic 5330.0
Elevation Aluminum 522000.0
Construction (Structural) Steel 266519.0
Glass# (float) 1020320.0
Glasswool 57624.0
Steel (galvanized) 200362.0
Steel Stainless 12573.0
Wallpaint Acrylic 127500.0
Floor Finishes Board plywood spruce 226.0
Ceramics 29864.0
Glasswool 160.0
Plaster White Finish 765812.0
PMMA sheet 8458.0
PVC Injection Molded 2776.0
Rock Wool 72.0
Steel (galvanized) 445.0
Steel Stainless 7270.0
Stone 58830.0
Wallpaint Acrylic 56790.9
Interior Fit Out Aluminum 18972.0
Board plywood meranti 11900.0
Board plywood spruce 135.0
Concrete (Grade 35) 840000.0
Construction (Structural) Steel 7473.0
Glass (float)# 34849.5
Glasswool 6354.5
Gypsum 31101.5
Plaster White Finish 152972.5
PMMA sheet 4790.6
Rock Wool 8257.0
Steel (galvanized) 13921.0
Steel Stainless 15095.0
Stone 17770.5
Wallpaint Acrylic 2364.5
Internal Walls and
Partitions Board plywood meranti 211933.0
Board plywood spruce 13526.6
Brick 844560.0
Concrete (Grade 35) 4857600.0
Rock Wool 43848.0
Steel (galvanized) 10962.0
Steel Hot Rolled (rebar) 300000.0
Steel Stainless 101.0
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Wall Finishes Ceramics 56876.0
Plaster White Finish 738250.0
Rock Wool 1224.0
Steel (galvanized) 8409.0
Steel Stainless 353069.0
Stone 273946.0
Wallpaint Acrylic 26085.0
# all glazing are measured in m2
(e) The architects and interior designers nowadays are also inherited with an additional
responsibility of selecting appropriate internal finishes materials that produce
minimal adverse impacts on indoor air quality. Cite two examples of interior
finishing materials and illustrate how they can become indoor pollutant sources.
(4 marks)
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Q4. A commercial building (Building A) has been submitted for a building environmental
performance assessment. Table Q4-1 summarizes the baseline and design parameters of
the building and the air-conditioning system.
Table Q4-1 Summary of baseline and design parameters of the building
Parameter Baseline Design Parameter Baseline Design
Ta 23 24 FP 15.5 9.3
LGT 25 20 AG 0.15 0.18
SPW 25 20 CFP 1 0.67
VR 1.1 1.3 PP 13.5 12
COP 4.0 4.5 CPP 1 0.9
You are given the below Equation (Q4.1) for prediction of annual electricity
consumption (AEC, kWh/m2) for air-conditioning:
AEC = 4.8 – 1.3 (AG×Ta/COP) + 75 (VR/COP) + 2.4 (LGT/COP)
+ 1.4 (SPW/COP) + 4.97 (CFP ×FP) + 0.69 (CPP×PP) (Q4.1)
Where,
AG = total window area per m2 floor area (m2/m2)
CFP = coefficient of fan flow rate control method
COP = coefficient of performance of the chillers
CPP = coefficient of pump flow rate control method
FP = total installed fan power intensity (W/m2)
PP = total installed pump power intensity (W/m2)
LGT = intensity of lighting load (W/m2)
SPW = intensity of equipment load (W/m2)
Ta = indoor design temperature (ºC)
VR = ventilation rate (m3/s.m2)
In the building environmental performance assessment, credits are given for better
indoor air quality (IAQ) and reducing energy use for air-conditioning.
Assuming that IAQ is assessed by the ventilation rate (VR, m3/s per m2) and energy use
for air-conditioning system is assessed by the percentage reduction in annual electricity
consumption (AEC, kWh/m2).
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(a) If Building A has scored 2 and 15 credits in IAQ and energy use for air-
conditioning respectively, and the credit scales for these two assessment criteria
are linear, determine:
(i) the % reduction in AEC of Building A;
(ii) the % reduction in AEC (zero credit is <= 10%);
(iii) the VR value for zero credit;
(iv) the credit scale for the two assessment criteria (Enter your answer in
Table Q4-2 given on the last page); and
(v) the optimum VR(s) to score the largest number of total credits for energy
use for air-conditioning and IAQ (Enter your answer in Table Q4-3
given on the last page).
(18 marks)
(b) Based on Equation Q4.1:
(i) suggest 6 viable measures (abbreviations should not be used) to score
additional energy credits; and
(ii) discuss why multi-step approach should be used to prioritize the viable
measures.
(6 marks)
(c) Besides IAQ and reducing energy use in buildings, the building environmental
performance assessment scheme assesses also other issues, explain why:
(i) some issues are assessed by relative approach and some are by absolute
approach. Elaborate your answer with examples;
(ii) high number of credits are given to the use of porous/open-grade
pavements. Discuss the ultimate benefits of their adoption; and
(iii) carbon emission from buildings is not directly assessed in Hong Kong.
(9 marks)
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Q5. (a) Water and Electricity tariffs in Hong Kong are adopting a progressive increase
structure as shown in Figure Q5-1 (a) and (b). From the slopes, it is noted that
the rate of increase in tariff for water is higher than electricity. Discuss:
(a) Water (b) Electricity
Figure Q5-1 Tariff Structure
(i) the possible reason(s) for the higher rate of increase in water tariff than
electricity tariff;
(ii) the possible reason(s) for a further drop in rate of increase in electricity
tariff for high consumption level;
(iii) why the first 12 m3 of water consumption is free but not electricity; and
(iv) the problem for setting water and electricity tariffs based on household
consumption.
(10 marks)
(b) To respond to the global agenda on sustainable development, the Hong Kong
SAR Government recently put in place the Building Energy Codes aiming to
reduce electricity use in new buildings and existing buildings.
(i) Name the five prescriptive codes for new buildings.
(ii) Name the performance-based code for new buildings.
(iii) Name the code for existing buildings.
(iv) Discuss the advantages of performance-based code over prescriptive
code.
(v) Discuss how enforcing the code for existing building can help reduce
building electricity use.
(vi) To demonstrate compliance with performance-based code, the use of
simulation tool for energy analysis is often specified. Discuss the
advantages of using simulation tools in the design stage.
(15 marks)
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(c) Besides electricity use in buildings, sustainable supply of fresh water nowadays
is emerging as one of the most critical issues in the world.
(ii) Discuss the environmental impact of water use?
(iii) State four causes of water inefficiency in buildings in Hong Kong.
(iv) State why reducing water use is important for sustainable development.
(v) State two measures that have been put in place by the HKSAR Government
aiming to reduce fresh water use in buildings.
(8 marks)
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BSE 5518 Sustainable Built Environment
Name _________________________ Student ID _______________________
Table Q4-2 Credit scale for the two assessment criteria (No. of credit has to
be an integer)
VR
(m3/s per m2)
No. of Credit(s) % Reduction in
AEC
No. of Credit(s)
>= 4 >= 20
>= 3 >= 19
>= 2 >= 18
>= 1 >= 17
< 0 >= 16
>= 15
>= 14
>= 13
>= 12
>= 11
>= 10
>= 9
>= 8
>= 7
>= 6
>= 5
>= 4
>= 3
>= 2
>= 1
< 0
Table Q4-3 Credits scored for VR and AEC
VR (m3/s per m2) 1.1 1.2 1.3 1.4 1.5
AECb (kWh/m2)
AECd (kWh/m2)
% reduction in AEC
Energy Credits
IAQ Credits
Total Credits
Note: AECb = baseline building AEC; AECd = design building AEC
(Please submit with your answer book)
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Graph paper
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