THE HONG KONG POLYTECHNIC UNIVERSITY
Department of Building Services Engineering
Subject : Sustainability and the Built Environment (BSE5518)
Level : 5
Session : 2020/2021 Semester 1
Release Date/Time : 1 December 2020, 6:30 pm
Collection Date/Time : 2 December 2020, 6:30 pm
This question paper has 5 pages.
Instructions to Candidates:
1. This is a take-home examination.
2. Answer all questions.
3. Total attainable marks for the examination paper is 100.
4. All questions carry equal marks.
© The Hong Kong Polytechnic University
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Programme : 33082/04001
1
Q1. The local government in Hong Kong is intended to develop a new suburban town to
house a large public housing estates encompassing 20 high-rise housing blocks and some
small private housing estates. The proposed site location is a deserted farmland located
at 35 km from the central business district.
(a) Suggest town planning principles that should be adopted in order to avoid turning
the new town into both a ‘horizontal and vertical sprawl’. Discuss the possible
consequences caused by a ‘sprawl’ and why the principles that you have suggested
can help achieve the objective.
(10 marks)
(b) Figure Q1.1 shows the proposed configuration of a street inside this new town.
Figure Q1.1 The proposed building and street configuration
(i) Comment on the air quality, thermal comfort and walkability during a sunny
cold winter afternoon with the wind blowing at a low speed in the direction
as shown in Figure Q1.1.
(9 marks)
(ii) In order to improve the streetscape of the above trunk road, it is proposed to
plant some trees along the footpaths. Explain whether this is a viable solution.
Also, do you think whether there are any differences if the trees are planted
in the centerline of the trunk road instead of along two sides of the footpaths?
(6 marks)
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2
Q2. (a) Compare the basic human exposure characteristics to noise and air pollutants.
Explain the major similarities and differences in principles adopted for mitigating
their daily exposure.
(10 marks)
(b) Discuss whether the Hong Kong Government should make the air quality standard
and the road traffic noise standard lower than the level currently adopted.
(5 marks)
(c) Reducing road traffic noise level has always been the major target for many local
government regulators in reducing noise pollution. However, it is worth pointing
out that noise annoyance rather than noise level is of the prime concern and many
other factors besides noise level also influence noise annoyance. Explain what they
are and postulate why the current noise mitigation approach did not take them into
account when formulating regulations.
(10 marks)
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3
Q3. (a) Two different tariff strategies, both adopting progressive increase structure, are
shown in Figure Q3.1. Identify the differences between the strategies and discuss
the reason(s) and implication(s).
(10 marks)
Figure Q3.1 Tariff strategies A & B
(b) Discuss the changes to an electric power sector which adopted the tariff ‘Strategy
A’ as shown in Fig.Q3.1 with possible reasons and the rationale of the changes.
(10 marks)
(c) Carbon tax of HK$500/Ton CO2 has been planned to be imposed to households
with an electricity consumption level higher than 500 kWh. By identifying the
carbon emission factor for electricity in Hong Kong, determine the carbon tax rate
in HK$/kWh and discuss the implications.
(5 marks)
kWh/household
Pr
ic
e
$
/ U
ni
t c
on
su
m
pt
io
n
Strategy A
Strategy B
i
ii
i
ii
iii
0 1000 2000
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4
Q4. In a building environmental performance assessment, credits are given for better daylight
performance and reduction in energy use for air-conditioning.
Assuming that daylight performance is assessed by the window-to-wall ratio (r) and
energy for an air-conditioned space is assessed by the percentage reduction in annual
thermal energy consumption (TEC, kWh/m2 year). The credit scales for these two
assessment criteria are given in Table Q4.1. Given also are the baseline and design
parameters in Table Q4.2 for the environmental assessment.
Table Q4.1 Credit scale for the two assessment criteria (No interpolation; credits
are in integer values)
r No. credit(s) % reduction in
TEC
No. of credit(s)
≥0.9 3 <10 0 ≥0.7 2 ≥10 4 ≥0.5 1 ≥20 8 <0.5 0 ≥30 12 ≥40 16 ≥50 20 Table Q4.2 Summary of baseline and design parameters of the building Para- meter Base- line Design Para- meter Base- line Design Additional capital cost HK$/m2 Additional maintenance cost HK$/m2 T 25 25 r 0.3 0.5 ? ? A 1000 1000 U 40 34 6 / 1 1 / 1 V 4000 4000 S 0.8 0.6 4 / 0.1 0.25 / 0.1 L 40 40 You are given the equation below for prediction of annual thermal energy consumption E for the air-conditioning space in kW/m2year, where T is indoor air temperature in °C, A and V are area and volume of the floor in m2 and m3 respectively, r is window-to-wall ratio, L is the characteristic length in m, U is overall U-value in W/m2K, and S is the shading coefficient. E = 27749 T−0.88 A−0.79 V0.22 r0.39 L0.37 U0.36 S0.49, where L=max(Width, Depth) of a floor plan. (a) Determine the % reduction in the TEC of the air-conditioned space for the design, and hence the number of credits to be scored by the design. (4 marks) © The Hong Kong Polytechnic University 5 (b) The building owner is considering of introducing combinations of one or more parameter(s) as the measures to score an additional energy credits. The life cycle cost of a period can be determined LCC = C + 4M, where C and M are the additional capital cost and maintenance cost of a measure. Data given in Table Q4.2 may be used. (i) State the measure(s) and determine the value(s) of the measure(s) in order to score 4 additional energy credits if a one-step approach is adopted to (a). (ii) Determine the cost-benefit ratio for the measure(s) in (i), if the benefit B= 8×TEC in HK$/m2. (iii) Prioritize the energy efficient measures to be selected for implementation if a multi-step approach is adopted for earning 4 additional energy credits to (b)(i). Briefly discuss your recommendation. (iv) Based on your answer for (b)(iii), or otherwise, determine the values of the measures to score an additional 4 more energy credits and the cost-benefit ratio. (9 marks) (c) Discuss how the carbon reduction goal is addressed in the BEAM Plus. (12 marks) © The Hong Kong Polytechnic University