Connecting, Nurturing, Creating for Sustainable Environment

Energy Efficient Retrofits Guide: Technologies
   

2. Energy Saving Technologies & Initiatives

3 steps to highly energy efficient buildings

There are 3 main steps that can be taken to improve the energy performance of existing commercial buildings (please see Section 4.7 for more details).

The focus of this Guide is on the third and last step. As retrofitting is the most costly step, building owners and managers need good information before committing capital to a retrofit plan. However, quantitative data as to “proof of performance” is often not available. The Guide and Retrofit Calculator focus on addressing this information gap. They aim to aid you in making informed decisions on retrofits by providing approximate cost and energy savings for common energy efficient equipment. This information is an initial first step, and further work will be needed in projects of a significant size to fully understand costs and savings.

Top tip: Integrate into your refurbishment programme & maintenance schedule

The time that wider refurbishment is being undertaken is the right time for energy efficiency retrofitting. It is a great opportunity to upgrade your system into an energy efficient one at the lowest possible cost. Introducing such technologies may mean slightly higher capital costs than like-for-like replacements initially, but will help you save significant amounts of energy and costs over the life cycles of their operations, as shown in Section 2.3. The labour costs and disruption to occupants will be reduced by integrating upgrades into refurbishment programmes.

 


2.1 Methodology: Modelling Costs & Savings of Key Technologies and Initiatives

The costs and savings of some of the most common energy efficient technologies in commercial buildings, as listed in Table 2 below, have been modelled according to Hong Kong Performance-based Building Energy Code and Appendix G of ASHRAE 90.1 and adjusted to reflect building operational scenarios. The assumptions for these technologies are listed in Appendix A.

Please note some technologies are usually only replaced when they approach their end-of-life because of their high capital cost, e.g. lifts, but others like office lights may be replaced when still fully functional. Therefore we have categorised each technology replacement into either a “fully functional scenario” or an “end-of-life scenario”. For the end of life scenario, we have included only the additional or incremental cost of the more energy efficient replacement technology.

In sub-section 2.2, we set out the top technologies for offices and for hotels with their energy and costs savings, calculated with reference to a sample building. This is followed by a brief description together with cost and energy savings of each technology in Section 2.4.

Table 2: List of energy saving technologies & initiatives

   

Type No. Initiative
With costs and saving potentials modelled
Façade 1 High Performance Glazing#
2 Solar Control Window Films
Lighting 3 Light-emitting Diode (LED) Lighting (in Landlord Areas)#
4 Tenant Office Lighting Design to 300lux
5 Tenant Office Lighting Control with Occupancy Sensors
Heating, Ventilation and Air Conditioning (HVAC) - Chiller Plants 6 Seasonal Chilled Water Temperature Reset
7 Variable Speed Drive (VSD) Chillers#
8  Oil-free Magnetic Bearing Chillers#
9  Variable Speed Drives (VSD) on Chilled Water Pumps#
HVAC - Air-side 10 Demand-controlled Ventilation (DCV)
11 Electronically Commutated (EC) Plug Fans#
12  Direct Current (DC) Fan Coil Units (FCUs)#
13 Variable Refrigerant Flow (VRF)#
14 Intelligent Building Control Systems
15 High Volume Low Speed (HVLS) Fans
16 Carbon Monoxide Sensor Controls for Carparks
Lifts 17 Variable Voltage Variable Frequency (VVVF) Lift Drives#
18 Regenerative Braking Lifts#
Hot Water Supply & Renewable Energy 19 Heat Pumps
20 Solar Water Heating (SWH) Systems
21 Solar Pool Heating
22 Photovoltaics
Initiatives that were NOT modelled
Others 23 Retro-commissioning (RCx)
24 High Efficiency Gas Technologies
25 Radiant Chilled Ceiling Systems (Chilled Beams)
26 Resizing Pumps
27 Task Lighting
28 District Cooling System (DCS)

End-of-life scenarios: these options are generally replaced only at their end-of-life stage.

 

  


2.2 Findings Regarding the 4 Building Types 

Tables 3 and 4 below show the top initiatives with respect to carbon abatement. To identify these initiatives we created sample buildings (see specifications in Appendix B), one for each building type, and modelled the cost and energy savings that it is reasonable to expect. The full result table is in Appendix C.

Please note: some costs in Tables 3 and 4 are split into landlords’ and tenants’ savings and may slightly differ from those listed in Appendix C.

The costs for “end-of-life scenario” technologies highlighted in purple are calculated based on incremental costs, the additional cost between a like-for-like replacement and an energy efficient equipment. If the energy efficient equipment is cheaper than the original replacement, we assume they have no costs thus their payback periods would be zero. Costs for other technologies are calculated based on their full costs.

Please note that the payback period and expected costs are calculated based on replacing fully functional existing equipment, unless otherwise specified. If your building equipment has reached its end-of-life and needs replacement, you can expect the actual payback period and expected costs to be lower than what is shown below.

To get a better understanding of costs and energy savings in those circumstances you can refer to our graphs in Section 2.3, or use our Retrofit Calculator explained in Section 3.

For those technologies which have high capital costs, such as lifts, glazing and chillers, we use “end-of-life scenarios”, including only the incremental capital cost of the more efficient technology in our calculations. We also show their savings in comparison with a like-for-like replacement at the end-of-life stage, as in practice it would be rare to seek to upgrade those facilities at any other stages. 

 

Table 3: Landlords' Perspective - Top 6 Options with Greatest Carbon Abatement

Landlords’ Top 6 Options with Greatest CO2 Reductions Over Building Lifecycle
No. Description Simple Payback Period [years] Approximated Cost over Lifecycle*  CO2 Reductions Over Lifecycle [tonnes]
Type 1 Office Building (Fig. 2)
10 Fresh air demand control 3.91 -$12,951,980 8,534.62
8 Oil-free Water-cooled Chillers 2.48 -$7,697,576 6,470.35
7 Variable speed drive water-cooled Chillers 7.39 -$6,565,048 4,839.74
2 Solar Control Window Film 13.59 -$820,854 4,618.67
15  High Volume Low Speed (HVLS) Fans 10.63 -$3,832,295 4,336.91
3 LED lighting in landlord areas 1.29 -$3,678,400 2,625.48
Type 2 Office Building (Fig. 4)
10 Fresh air demand control 0.56 -$22,598,488 14,376.27
8 Oil-free Water-cooled Chillers 6.05 -$9,248,483 8,198.25
4 Tenant Office Design to 300lux 0.02 -$8,429,773 5,234.46
7 Variable speed drive water-cooled Chillers 7.03 -$5,172,386 4,933.93
15 High Volume Low Speed (HVLS) Fans 11.52 -$3,199,446 4,668.39
3 LED lighting in landlord areas 1.07 -$4,709,919 3,700.92
Type 3 Office Building^ (Fig. 6)
3 LED lighting in landlord areas 1.31 -$3,587,963 3,007.13
16 Carpark fans with VFD and CO Sensor 1.36 -$2,410,275 1,638.86
17 High efficiency lifts 0.00 -$1,634,919 1,010.99
18 Regenerative braking lifts 3.06 -$1,301,586 1,010.99
22 Photovoltaics (PV) 34.57 $758,560 644.00
Hotel Building (Fig. 8)
8 Oil-free Water-cooled Chillers 5.97 -$28,051,977 21,190.85
7 Variable speed drive water-cooled Chillers 6.03 -$19,345,066 14,679.18
12 DC Fan Coil Units 4.51 -$18,211,286 13,808.32
3 LED lighting 0.76 -$18,612,359 11,624.14
9 Variable speed drive chilled water pumps 0.17 -$17,815,928 9,522.58
19 Heat pumps for domestic hot water 4.98 -$11,863,282 8,375.54

* We assumed existing buildings will remain for 20 more years; negative costs represent savings
^ Less than 6 options apply to landlords for Office Building Type 3


Table 4: Tenants' Perspective - Top 3 Options with Greatest Carbon Abatement

Tenants’ Top 3 Options with Greatest CO2 Reductions Over Building Lifecycle
No. Description Simple Payback Period [years] Approximated Cost over Lifecycle*  CO2 Reductions Over Lifecycle [tonnes]
Type 1 Office Building^ (Fig. 2)
4 Tenant Office Lighting Design to 300lux 0.05 -$10,974,959 5,872.91
5 Tenant Office Lighting Control with Occupancy Sensors 2.07 -$3,289,081 2,197.80
Type 2 Office Building (Fig. 4)
4 Tenant Office Lighting Design Reduced to 300lux 0.03 -$16,512,660 10,276.11
5 Tenant Office Lighting Control with Occupancy Sensors 1.38 -$5,366,551 3,848.75
12 DC Fan Coil Units 5.77 -$3,565,839 3,584.31
Type 3 Office Building (Fig. 6)
4 Tenant Office Lighting Design to 300lux 0.03 -$23,353,701 14,528.13
13 VRF or High efficiency split type 3.82 -$7,277,036 9,892.95
5 Tenant Office Lighting Control with Occupancy Sensors 0.98 -$7,895,974 5,412.88
Hotel Building - not applicable as hotel customers are not tenants

* We assumed a 20-year lifecycle for existing buildings; negative costs represent savings
^ Less than 3 options apply to tenants for Office Building Type 1

Please note: Tenants should also consider replacing lighting in their rented premises with LEDs as this would lead to high carbon abatement with a good payback, similar to replacement in landlord areas. 


2.3 A Visual Representation of Energy and Carbon Savings [Marginal Abatement Cost Curves]

(Please click the link above)


2.4 Energy Saving Technologies and Initiatives: A Directory - How much can you save? When are they most impactful?

  • Façade
    • 2.4.1 High Performance Glazing
    • 2.4.2 Solar Control Window Films
  • Lighting
    • 2.4.3 Light-emitting Diode (LED) Lighting (in Landlord Areas)
    • 2.4.4 Tenant Office Lighting Design to 300lux
    • 2.4.5 Tenant Office Lighting Control with Occupancy Sensors
  • HVAC - Chiller Plants
    • 2.4.6 Seasonal Chilled Water Temperature Reset
    • 2.4.7 Variable Speed Drive (VSD) Chillers
    • 2.4.8 Oil-free Magnetic Bearing Chillers
    • 2.4.9 Variable Speed Drives (VSD) on Chilled Water Pumps
  • HVAC - Air-side
    • 2.4.10 Demand-controlled Ventilation (DCV)
    • 2.4.11 Electronically Commutated (EC) Plug Fans
    • 2.4.12 Direct Current (DC) Fan Coil Units (FCUs)
    • 2.4.13 Variable Refrigerant Flow (VRF)
    • 2.4.14 Intelligent Building Control Systems
    • 2.4.15 High Volume Low Speed (HVLS) Fans
    • 2.4.16 Carbon Monoxide Sensor Controls for Carparks
  • Lifts
    • 2.4.17 Variable Voltage Variable Frequency (VVVF) Lift Drives
    • 2.4.18 Regenerative Braking Lifts
  • Hot Water Supply & Renewable Energy
  • Other Non-modelled Initiatives
    • 2.4.23 Retro-commissioning (RCx)
    • 2.4.24 High Efficiency Gas Technologies
    • 2.4.25 Radiant Chilled Ceiling Systems (Chilled Beams)
    • 2.4.26 Resizing Pumps
    • 2.4.27 Task Lighting
    • 2.4.28 District Cooling System (DCS)

 

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