Connecting, Nurturing, Creating for Sustainable Environment

Energy Efficient Retrofits Guide: Lighting
   

2.4.3 Light-emitting Diode (LED) Lighting (in Landlord Areas)

Why?

§  significant energy savings
§  does not need to modify the existing system

Where does it work best?

Office Buildings (Types 1, 2 & 3)

  • open plan office areas
  • core areas such as fire escapes

Hotel Buildings

  • back-of-house office areas
  • cove lighting 

Image Source: Lighting 4 Diamonds T8 LED Showcase Lighting

Overview

Light-emitting diodes (LEDs) have significantly higher efficiency than incandescent lamps. Newer LEDs are also more efficient than fluorescent lamps, as LEDs convert electric energy more efficiently to light energy.

There are various types of LED lamps, and certain LED tubes can fit into existing fluorescent fixtures, with almost no disruption to the building occupants. This Guide specifically focuses on retrofitting replacement lamps for T8 fluorescent tubes, as T8 tubes are common in older Type C office buildings, and some back of house (BOH) hotel areas.

Modelled Costs and Saving Potentials (assumptions are listed in Appendix A)

Retrofitting LED T8 Tubes

Building Type

Office Types 1, 2 & 3

Hotel

Scenario

End-of-Life

Total Cost

End-of-Life

Total Cost

Capital Cost (per m2 of building area)

HK$16

HK$27

HK$16

HK$25

Payback Period (years)

1.3

2.2

0.8

1.3

Saving Potentials (per m2 of building area)

Cost

HK$12/year

HK$21/year

Energy

11 kWh/year

18 kWh/year

Carbon

6 kg CO2-e/year

11 kg CO2-e/year

Advantages

  • LED technology has advanced and become mature
  • quality LEDs have similar lighting quality to fluorescent T5 & T8 tubes
  • significant energy savings
  • available for direct replacement, so no extra efforts needed to modify the existing system
  • greater reliability as LED tubes have longer lifetimes than fluorescent tubes
  • modern LED systems have embedded functions like occupancy sensors and remote controls, that can be easily integrated into automated control systems
  • additional energy savings from reduced cooling load
  • higher energy efficiency as a directional light source
  • cheaper than retrofitting to T5 lamps, which requires an upgrade of the entire fitting

Limitations

  • toxicity hazard from the disposal of LEDs, as they may contain lead and arsenic
  • initial cost of LED tubes would be higher than T5 & T8 tubes

Additional Considerations

  • in most cases, retrofits are simple and no other changes are required:
    • if a magnetic transformer is used, it does not need to be replaced
    • if an electric transformer is used, it will need to be bypassed and will require an electrician plus additional installation time
  • you can also retrofit the existing wiring for LED luminaires that will be more cost effective in the long run, with extended lifetime and increased efficiency
  • projects should consider dimming needs for LED lamps and check whether the compatible drivers are installed to support this

Relevance to Landlords and Tenants

  • switching to LED lighting can be done by both landlords and tenants – shared areas and individual premises -  and will therefore result in cost savings for both
  • only landlord savings – for shared areas - are calculated in the Retrofit Calculator, as tenants are usually restricted by reinstatement clauses that discourage improvements in their rented premises.

Case Study – LED Lights

In 2014, 49 T8 light fixtures were replaced with LED panels in the public area of one floor of an office building in Kowloon Tong. Of the 49 light fixtures, 14 are essential lighting panels operating 24 hours per day throughout the week, 29 non-essential lights at the corridor operating 12.25 hours per day on weekdays, and 6 were non-essential lights in toilets operating at 13.75 hours per day during weekdays and 9.5 hours on Saturdays.

Since the retrofit work took place in the public area of the office building, disturbance to building occupants was not severe. Efforts were made to further reduce the disturbance to building occupants such as by scheduling retrofit works to take place on weekends and holidays.

The replacement of T8 fixtures with LED panels led to a reduction of electricity consumption from lighting by 57%, and an annual energy saving of more than 9,800 kWh. The energy savings translated to a payback period of approximately 3.5 years. If all of the light fixtures were to operate at 24 hours per day, the corresponding payback period would be even shorter.

 

Information provided by Business Environment Council


2.4.4 Reduced Illuminance to 300lux

Why?

§  easy implementation
§  low cost with significant savings

Where does it work best?

Office Buildings (Types 1, 2 & 3)

  • open plan office areas

Hotel Buildings

  • back-of-house office areas

Image Source: The Give Grid

Overview

Lighting systems in buildings are often designed to be much brighter than needed. As office work used to be heavily reliant on paperwork, 500 lux was considered to be the appropriate illuminance level in the past. However, modern offices often operate with computer systems, so 300 lux will be adequate for the majority of offices[1].

Energy used for lighting is directly proportional to illuminance levels. By reducing the illumination level from 500 lux to 300 lux, significant energy can be saved. The easiest way to reduce illuminance is to simply replace existing light tubes with lower output ones, or delamp the lighting systems (for instance, remove 1 light tube for fittings with multiple light tubes). Better effects can be achieved by modifying the entire lighting layout and light fittings, but this would mean higher capital costs.

Modelled Costs and Saving Potentials (assumptions are listed in Appendix A)

Reduction to 300 lux by retrofitting to lamps with lower output*

Capital Cost (per m2 building area)

HK$2*

Payback Period (years)

 0

Saving Potentials (per m2 building area)

Cost

HK$41/year

Energy

36 kWh/year

Carbon

22 kg CO2-e/year

 *Reducing illuminance to 300 lux by delamping would not incur any capital cost

Advantages

  • straightforward implementation, and original light fittings can be retained
  • relatively low capital cost with significant energy savings
  • procurement and maintenance costs can be reduced as less light tubes would be needed
  • delamping is reversible – occupants can simply put light tubes back if the illuminance level is insufficient

Limitations

  • occupants may need time to adapt to new illuminance levels
  • delamping may affect the aesthetic of light fittings
  • high capital cost if the entire lighting layout needs to be changed

Additional Considerations

  • lighting uniformity needs to be checked after the replacement of lower output lamps or delamping
  • reducing illuminance levels can be implemented in conjunction with LED lighting to achieve even greater energy and cost savings
  • some tenants may still consider 500 lux to be a standard requirement, so expectation setting or management may be needed
  • task lighting (please see Section 2.4.27) can be used to provide supplement for work with high lighting power requirements

Relevance to Landlords and Tenants

  • this can be done by both landlords and tenants
  • the energy savings from reduced illuminance in tenant areas is primarily beneficial to tenants as they generally pay electricity bills for lighting, however, landlords may benefit from having premises for rental with lower operational costs

2.4.5 Daylight and Occupancy Sensors

Why?

§  significant energy savings
§  do not need to modify the existing system

Where do they work best?

Office Buildings (Types 1, 2 & 3)

  • open plan office areas and meeting rooms
  • enclosed space such as cellular offices, fire escapes, bathrooms, corridors, etc.
  • back-of-house office areas

Hotel Buildings

  • back-of-house office areas

Image Source: Honeywell Wireless Occupancy Sensors

Overview

Daylight sensors can modulate lighting levels in response to the strength of sunlight indoors, and maintain the required illuminance levels. These sensors can be installed in lighting zones located near windows or skylights.

Occupancy sensors work in a similar fashion: they detect the presence of occupants in a room using infrared and/or ultrasonic technology, and switch off or dim down (e.g. to 20% of the original lux levels) the lamps when the zone is unoccupied. 

Modelled Costs and Saving Potentials (assumptions are listed in Appendix A)

Occupancy Sensors (not modelled for hotels)

Capital Cost (per m2 building area)

HK$29

Payback Period (years)

 1.9

Saving Potentials (per m2 building area)

Cost

HK$15/year

Energy

14 kWh/year

Carbon

8 kg CO2-e/year

Advantages

  • technology is mature
  • significant energy savings when combined with dimmable lighting and daylight access
  • reduced lamp usage and also frequency of replacements
  • does not require behavioural change

Limitations

  • daylight sensors are only effective for areas with daylight access
  • dimming controls for lighting will likely require an upgrade of the control electronics (ballast), resulting in additional costs
  • users may not be accustomed to intermittent lighting from occupancy sensors with motion control

Additional Considerations

  • wiring cost will be a major cost component and installation, therefore needs to be carefully planned combining with more extensive redecoration/refurbishment if possible
  • utilizing 2-in-1 (daylight and occupancy) sensors, and sharing sensors between 2 to 3 light fittings can reduce wiring costs while still maintaining good zoning control
  • some LED lighting systems have built-in sensors, that may save capital costs and installation time
  • occupancy sensors need to be used with caution to avoid health & safety issues, for instance they will not be suitable for HVAC plant rooms; but they can also be wired to switch off part of (e.g. 50%) the lighting system through dual circuit designs
  • delay timers can be used with occupancy sensors to reduce unwanted nuisance or avoid over-sensitivity
  • wiring flexibility can be improved by assigning each lighting fixture an individual IP address, but would cost significantly more than a local control system that only requires simple wiring
  • the 2015 Edition of Building Energy Code has minimum requirements for lighting installations, including daylight controls and automatic timers, so projects undergoing major retrofit works will be required to comply with these conditions

Relevance to Landlords and Tenants

  • daylight sensors will result in cost savings for tenants when installed in tenant’s premises
  • occupancy sensors can be installed in shared areas and individual premises, thereby reducing energy costs for both tenants and landlords

Case Study – Lighting Occupancy Sensors

In 2014, occupancy sensors were installed at the toilets of one floor an office building in Kowloon Tong installed. There are both essential and non-essential LED panel light fixtures at the toilets, and 4 occupancy sensors were installed to control 5 non-essential lights. Essential lights are turned on 24 hours a day throughout the week, while prior to the retrofit, non-essential lights were switched on within the daily opening schedule of the building through a timer. That is, non-essential lights operate for 13.75 hours per day during weekdays and 9.5 hours on Saturdays. With the occupancy sensors installed, non-essential lights turns on upon sensing an occupant, then turns off if no occupant is detected within the next 5 minutes.

With the installation of occupancy sensors, the electricity consumption of the non-essential lights were reduced by more than 29% and an annual energy saving of close to 186 kWh.

Due to the small scale of this retrofit project, the absolute amount of energy saved was limited and the initial costs were relatively large compared to the savings accrued. This is attributed to the lights originally operating on a non-essential schedule already, and each sensor controls a small number of light fixtures. In other words, energy savings could have been enhanced if more light fixtures were controlled per occupancy sensor.

 

Information provided by Business Environment Council

 

Case Study 2 – Lighting Occupancy Sensors

In 2015, lighting occupancy sensors were installed in 150 refuse rooms in a residential complex in Tai Kok Tsui. In each room, one sensor controls two T5 light fixtures. Approximately an hour was required to install each sensor in the rooms.

There is one refuse room on every story within the buildings, at which 3 to 4 apartment units on each floor. Given that the number of occupants on each floor is not high, and that building occupants take little time to dispose refuse into waste receptacles and recycling bins, the refuse rooms are often unoccupied.

Prior to installing occupancy sensors, lights in the refuse rooms were switched on permanently – 24 hours a day. After occupancy sensors were installed, lights in the refuse rooms on average switch on for 30 minutes each day. This is a 98% reduction in time which the lights are turned on. With the occupancy sensors, it is estimated that more than 2,900 kWh is saved monthly, compared to prior to the sensors’ installation.

 

Information provided by SHKP and its property management subsidiaries

 

 

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