Connecting, Nurturing, Creating for Sustainable Environment

Energy Efficient Retrofits Guide: Appendices
   

Appendices

Appendix A Assumptions used in the 22 modelled Energy Saving Initiatives

Appendix A1 Assumptions for Office Buildings

Section

Upgrade Option

Scenario

Base Case

Proposed Case

Façade Strategies

2.4.1

High Performance Glazing

12mm clear glass with U-value=5.67 and Shading Coefficient (SC) =0.58 for all facade glazing

Double-glazed fenestration with U-value=2.8 and SC = 0.34 for all facade glazing

2.4.2

Solar control window film

12mm natural white glass with SC = 0.58 for all facade glazing

12mm clear glass with solar control film with SC=0.34

Lighting Strategies

2.4.3

LED lighting in landlord areas

T8 fluorescent tube with:
- Common space designed to 300lux
- Toilet designed to 300lux
- Carpark designed to 150lux

Replacement of T8 fluorescent tube with T8 LED with:
- Common space designed to 300lux
- Toilet designed to 300lux
- Carpark designed to 150lux

2.4.4

Tenant Office Design to 300lux

T5 Type 1 Office:  fluorescent tube designed to 500lux

Type 2 Office: T8 fluorescent tube designed to 500lux

T5 fluorescent tube designed to 300lux

2.4.5

Tenant Office Lighting Control with Occupancy Sensors

No automatic sensor control

Occupancy detection control for all office tenant space

HVAC – Chiller Plant

2.4.6

Seasonal chilled water temperature reset

Chilled water supply temperature is set at 7°C throughout the year

Chilled water setpoint raise from 7°C to 9°C when the cooling load is low enough to do so

2.4.7

Variable speed drive water-cooled Chillers

Non-VSD centrifugal water-cooled chiller (COP specified by users in the Calculator)

VSD centrifugal water-cooled chiller with COP=6.1

2.4.8

Oil-free Water-cooled Chillers

Non-VSD electric open centrifugal water-cooled chiller (COP specified by users in the Calculator)

Oil free water-cooled chiller with COP=6.7

2.4.9

Variable speed drive chilled water pumps

Decoupled circuit; CSD control for all chilled water and condenser water pumps

Decoupled circuit; CSD on primary chilled water pumps and condenser water pumps, VSD on secondary chilled water pumps

HVAC – Air-side

2.4.10

Fresh air demand control (Office Types 1 & 2 only)

Fresh air delivered by Primary Air Handling Unit with no fresh air demand control

Fresh air delivered by Primary Air Handling Unit with VSD drive, modulate fresh air supply to each floor based on CO2 measurement

2.4.11

Plug fans (Fan wall) for AHU/PAU

AHU with centrifugal fan driven by induction AC motor through belt-pulley (Specific fan power = 2.3W/l/s)

AHU with fans driven by brushless motors with 18% fan power saving
 

2.4.12

DC fan coils (Office Type 2 only)

FCU specific fan power = 0.6W/l/s

FCU average specific fan power = 0.2W/l/s

2.4.13

Variable refrigerant flow or high efficiency split type (Office Type 3 only)

Ducted commercial split type AC serving all office area, with:
COP=2.3 or alternative value entered by user
Indoor unit Specific fan power = 0.68W/(l/s)

Ducted commercial VRF serving all office area with:
COP=3.77
Indoor unit Specific fan power = 0.54W/(l/s)

2.4.14

Smart controls/BMS

No smart control provision

Smart control of chiller plant system that can reduce chiller plant water side energy by about 10%.

2.4.15

High-volume low-speed (HVLS) fans

No low speed high volume fan provision

Employ HVLS fans with 1.5m diameter for all office areas. Assume AC setpoint can be raised 2.2°C.

2.4.16

Carpark fans with VFD and CO sensor

6 ACH of supply and exhaust delivered by constant speed fans

50% fan volume reduction when CO level is lower than threshold.

Elevators

2.4.17

High efficiency lifts

Conventional traction lift with ACVV motor (AC motor drive with variable voltage controller)

Traction lift with variable voltage variable frequency (VVVF) drive

2.4.18

Regenerative braking lifts

Conventional traction lift with ACVV motor and equipped with power regeneration drive

Hot Water and Renewable Energy

2.4.19

Heat pumps for domestic hot water

N/A (modelled for Hotel buildings only)

N/A (modelled for Hotel buildings only)

2.4.20

Solar hot water (SHW)

N/A (modelled for Hotel buildings only)

N/A (modelled for Hotel buildings only)

2.4.21

Solar pool heating

N/A (modelled for Hotel buildings only)

N/A (modelled for Hotel buildings only)

2.4.22

Photovoltaics (PV)

No PV provision

Mono-crystalline modules with 18% efficiency installed on user-set roof area.

 

Appendix A2 Assumptions for Hotel Building 

Section

Upgrade Option

Scenario

Base Case

Proposed Case

Façade Strategies

2.4.1

High Performance Glazing

12mm clear glass with U-value=5.67 and Shading Coefficient (SC) =0.58 for all facade glazing

Double-glazed fenestration with U-value=2.8 and SC = 0.34 for all facade glazing

2.4.2

Solar control window film

12mm natural white glass with SC = 0.58 for all facade glazing

12mm clear glass with solar control film with SC=0.34

Lighting Strategies

2.4.3

LED lighting

T8 fluorescent tube with:
- Common space designed to 300lux
- Toilet designed to 300lux
- Carpark designed to 150lux

- Kitchen designed to 500 lux

- Storage and plant room designed to 200 lux

Replacement of T8 fluorescent tube with T8 LED with:
- Common space designed to 300lux
- Toilet designed to 300lux
- Carpark designed to 150lux

- Kitchen designed to 500 lux

- Storage and plant room designed to 200 lux

2.4.4

Tenant Office Design to 300lux

N/A (modelled for Office buildings only)

N/A (modelled for Office buildings only)

2.4.5

Tenant Office Lighting Control with Occupancy Sensors

N/A (modelled for Office buildings only)

N/A (modelled for Office buildings only)

HVAC – Chiller Plant

2.4.6

Seasonal chilled water temperature reset

Chilled water supply temperature is set at 7°C throughout the year

Chilled water setpoint raise from 7°C to 9°C when the cooling load is low enough to do so

2.4.7

Variable speed drive water-cooled Chillers

Non-VSD centrifugal water-cooled chiller (COP specified by users in the calculator)

VSD centrifugal water-cooled chiller with COP=6.1

2.4.8

Oil-free Water-cooled Chillers

Non-VSD electric open centrifugal water-cooled chiller (COP specified by users in the calculator)

Oil free water-cooled chiller with COP=6.7

2.4.9

Variable speed drive chilled water pumps

Decoupled circuit; CSD control for all chilled water and condenser water pumps

Decoupled circuit; CSD on primary chilled water pumps and condenser water pumps, VSD on secondary chilled water pumps

HVAC – Air-side

2.4.10a

Fresh air demand control-primary air unit for dining, multi-function and kitchen areas

No fresh air demand control

Modulating fresh air supply according to CO2 level. 

Applied to: dining, multifunction, kitchens.

Minimum turn down ratio = 30%

2.4.10b

Guest room fresh air fan off-peak cycling

No fresh air demand control

Fresh air supply to guest room will be cycle off by 2 hours per day (1.00pm - 3:00pm) the supply fan.

2.4.11

Plug fans (Fan wall) for AHU/PAU

AHU with centrifugal fan driven by induction AC motor through belt-pulley (Specific fan power = 2.3W/l/s)

AHU with fans driven by brushless motors. Fan power saving=18%

2.4.12

DC fan coils

FCU specific fan power = 0.6W/l/s

FCU average specific fan power = 0.2W/l/s

2.4.13

Variable refrigerant flow or high efficiency split type (Office Type 3 only)

N/A

N/A

2.4.14

Smart controls/BMS

No smart control provision

Smart control of chiller plant system that can reduce chiller plant water side energy by about 10%.

2.4.15

High-volume Low-speed (HVLS) Fans for BOH Offices and Lobbies

No high volume low speed fan provision

Employ HVLS fans with 1.5m diameter for BOH office areas and main lobby. Assume AC setpoint can be raised 2.2°C.

2.4.16

Carpark fans with VFD and CO sensor

6 ACH of supply and exhaust delivered by constant speed fans

50% fan volume reduction when CO level is lower than threshold.

Elevators

2.4.17

High efficiency lifts

Conventional traction lift with ACVV motor (AC motor drive with variable voltage controller)

Traction lift with variable voltage variable frequency (VVVF) drive

2.4.18

Regenerative braking lifts

Conventional traction lift with ACVV motor and equipped with power regeneration drive

Hot Water and Renewable Energy

2.4.19

Heat pumps for domestic hot water

DHW heated by gas-fired boiler with efficiency of 80% to produce hot water at 65°C

Two stage water heating:

≤20-45°C: by heat pump

45-65°C: by gas boiler

 

- Heat pump COP = 3.3

- Gas-fired boiler = 80% (same with Baseline)

2.4.20

Solar hot water (SHW)

Water heating is served by gas-fired boiler with 80%

Evacuated-tube solar collectors with efficiency of 60%. Size of solar collectors entered by user.

2.4.21

Solar pool heating

Water heating is served by gas-fired boiler of 80% efficiency

Evacuated-tube solar collectors with efficiency of 60%. Size of solar collectors entered by user.

2.4.22

Photovoltaics (PV)

No PV provision

Mono-crystalline modules with 18% efficiency installed on user-set roof area.


Abbreviations:
AHU = Air handling unit
BEC = Building Energy Code
BOH = Back-of-house
CO = Carbon monoxide
COP = Coefficient of Performance

CSD = Constant speed drive
DC = Direct current
PAU = Primary air handing unit
VSD = Variable speed drive
VRF = Variable refrigerant flow

Appendix B Technical Details of Buildings Modelled for Sample Studies (Section 2.2)

 


Appendix C Model Output Results for Sample Studies (Section 2.2)

Appendix C1 Type 1 Office Building 

 

Appendix C2 Type 2 Office Building 

 

Appendix C3 Type 3 Office Building 

 

Appendix C4 Hotel Building 


Appendix D Methodology of the Retrofit Calculator

Step 1: Data collection, finalisation and review

  • Initiatives and building types to be analysed
    • For Office buildings, three types broadly representing a range of current building stock were modelled.
    • For hotels, there is more diversity in the different areas and functions that hotels contain. Different typical areas were modelled
  • Information on the initiatives necessary for the modelling and analysis works were collected
    • Information was collected from vendors and previous project experience
    • References for typical office building operation

Step 2: Calculation and modelling works

  • The energy simulation methodology detailed in the Hong Kong Performance-based Building Energy Code and Appendix G of ASHRAE 90.1 was adopted for this study with adjustments to mimic the operational scenarios
  • Typical baseline building models to represent average buildings, or spaces within that building, were developed in the following agreed sectors:
    • Internal and external zones
    • Reasonable internal profiles
    • MEP system, equipment systems and facade construction that are common for typical buildings in Hong Kong
  • Adjustments were made such that the energy model can reflect operation inefficiency, degradation of plant performance, obsolete building standards, overprovision, and actual operational hours. For example:
    • Increasing lighting power density (LPD)
    • Decreasing HVAC equipment efficiency and older technology
    • Less efficiency lift equipment
    • Lower performance facade and building envelope
    • Longer operation hours
  • Dynamic annual simulations on the baseline models were carried out to determine:
    • Baseline annual energy consumption – kWh/m2/annum
    • Baseline annual carbon emissions – CO2eq/m2/annum
  • Variations to the baseline building models to reflect the implementation of the technologies/initiatives, while keeping all other variables identical, were run to determine:
    • Off-axis model annual energy consumption, and thereby the annual energy savings
    • Off-axis model annual carbon emissions, and thereby the annual energy savings
  • Output data from the building models and financial information was used to determine for each technology/initiative and model:
    • The cost of each technology/practice per unit of energy abated per square meter - $/kWh abated/m2
    • The energy abatement potential of each technology/practice per square meter – kWh abated per year/m2
  • The 2016 carbon emission factor of 0.6 kg CO2-e/kWh[1] for Hong Kong was used to determine for each technology/initiative:
    • The cost of each technology/practice per unit of carbon abated per square meter - $/ Tonnes CO2eq abated per year/m2
    • The carbon abatement potential of each technology/practice per square meter – Tonnes CO2eq abated per year/m2
  • Output data from the building models were utilised to create a marginal abatement cost curve (MACC) for the typical buildings represented by the models. The study assumes that remaining building life-cycle is 20 years.


[1] Calculated based on the weighted average of carbon emissions from the two electric power companies in Hong Kong, the year 2016.

Hongkong Electric Company emissions:

https://www.hkelectric.com/en/CorporateSocialResponsibility/CorporateSocialResponsibility_CDD/Documents/SR2016E_performance_targets.pdf

CLP Power Hong Kong Limited emissions: 

https://www.clp.com.hk/en/about-clp-site/media-site/resources-site/publications-site/Documents/CLP-Information-Kit-English.pdf

 

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