With every passing day, new technologies and machines are being invented and with new inventions and increasing population of world, there has been a tremendous increase in the energy demand. Lighting is one of the major reasons of this increased demand of energy, since it consumes a significant amount of energy in any kind of building. Being a developing country, with growing population, Pakistan is facing severe energy crisis. However, a significant amount of energy can be conserved by making our lighting design energy efficient. For this purpose, Surgical Tower and Ghari Ward of Mayo Hospital have been selected as case studies and retrofitting of lighting system has been proposed for them, with help of Dialux and manual calculations, by using energy efficient lights, i.e. Light Emitting Diodes (LED-s), instead of traditional bulbs. This retrofitting, along with various calculations, have resulted in exceptional energy and cost saving values, with a payback period of 1-3 years.
Keywords: Light Emitting Diode (LED), Digital Addressable Lighting Interface (DALI), Incandescent Lamps (IL), Utilization Factor (UF), Maintenance Factor (MF)
Energy is one of the fundamental requirements for the human development and economic growth. In Pakistan severe electricity shortages has occurred due to demand supply gap which led to blackouts and it has severely damaged the commercial setup as major chunk of electricity is consumed by industry. One way to cope with the same is to adopt the passive building design and conserve energy in buildings by smart technologies.
Lighting systems that exploit control strategies, such as daylighting, personal controls, and load shedding, have enormous potential to reduce lighting energy consumption and peak demand in commercial buildings, enhance occupant comfort, and improve organizational efficiency. However, even with new advances in digital lighting technology, such as the digital addressable lighting interface (DALI) protocol, realizing the benefits of integrated lighting controls has been slow and restricted newly constructed buildings. Retrofitting advanced lighting controls into existing buildings required adding control wiring, which often entails prohibitively expensive labor costs. A lighting control solution that does not require additional control wiring or skilled commissioners is essential to deploying integrated lighting controls into existing buildings and gaining the associated energy benefits.
Energy saving while maintaining the required lighting level is a challenging task in designing lighting schemes for buildings. Lighting is a large growing source of energy demand. For artificial lighting, most common sources are the Incandescent Lamps (IL) and compact fluorescent lamps (CFL). IL is inefficient, converts 90% of electrical energy into heat and short bulb life. CFLs are more efficient than incandescent bulbs in terms of energy saving long life but it contains hazardous material mercury, slow response time and recycling issues. This leads to a unique lighting technology called Light Emitting Diodes (LED).
LEDs lights can potentially overcome many problems, low power consumption, fast switching, minimum cost incurred on maintenance, high output (lumen/ Watt), long-lasting, high tolerance to humidity, no radiations, no recycling issues like CFLs and no premature lamp failure like incandescent and ecofriendly. Therefore, traditional light bulbs are replaced with LED for energy saving, financial effects, better performance, high forbearance to dampness, cool operation extended life and are highly efficient.
Commercial buildings have significant energy savings potential if they benefit from daylight. Secondary spaces such as corridors when controlled by combination of daylight and occupancy sensors seem to present significant savings as well. In this paper, the retrofitting of the lighting installation in a corridor and ward in a hospital building is presented based on retrofitting reports from the lighting design software. The energy savings are calculated based on measurements reaching 85% for a working day and they are higher compared to the case of retrofitting the lighting only by changing the fluorescent lamps with LED ones at the same cost(approximately).
Section 1 of the paper explains the modern lighting technology and low cost-efficient system design with LED lights. Section 2 describes the methodology of the research opted for replacement of conventional lights by LEDs for a hospital setup as per proposed lightning design to achieve energy and cost saving. In section 3 a case study is presented for a hospital setup through installation of efficient lamps as per developed lightning design. Results are discussed in section 4 of the paper. Paper is concluded in section 5.
1.1 Purpose: This paper discusses the existing lighting condition of an old and new building of a government hospital i.e. Mayo Hospital, Lahore. Then develop a new lighting scheme with modern lights to save most of the energy loss through the old lighting equipment and making the system more efficient and cost saving.
2. Methodology of Research
In proposed strategy first of all site for the project is selected, its area is measures along with the existing illumination level with the lux meter and number of lamps installed in that space. Measured illumination levels are then matched with the American National Standards Institute (ANSI). If the existing illuminance level is less than the standard or it is higher than the standard so retrofitting has to be done for better and economical lighting design. Then design layout using DILUX 4.31 and generate report.
In order to check the new lighting scheme, do energy saving and cost savings calculations. Finally, payback period has been calculated to justify the implementations of new lighting scheme.
A new lighting scheme is developed by using measurements of selected area and adding the standards for that specific environment to simulation software Dialux 4.13. As per design, the hardware is installed and illumination level is measured for LED lights by using Lux meter and results are compared with that of conventional lights prior to installation of LED lights.
The quality of light reaching at certain surface is usually the main consideration of lighting system design. The quantity of light is specified by illuminance measured across the work plane an average figure is used.
The lumen method is used to determine the number of lamps that should be installed for a given area or room. This method is used technique of lighting design which is valid if the light fittings are to be mounted overhead in a regular pattern.
The luminous flux output of each lamp needs to be known as well as details of the luminance and room surfaces usually the luminance is already fixed.
N = (E * A)/(F * UF * MF)
N (number of lamps required)
E (illuminance level)
A (area of working plane)
F (average luminance flux from each lamp)
UF (utilization factor)
MF (maintenance factor)
For lighting design of MAYO hospital, we used two different approaches. In new Surgical tower of hospital, we fixed the number of lamps and calculate the LDL value of the lamps, in this way we achieve the required E value according to standards.
Secondly, in Ghari ward of hospital we calculated the E value by lumen method which is not according to standard so here we have suggested a new lighting design.
Calculation for both wards from Dialux and lumen method is given below.
3.1 Ghari Ward:
Dialux Report of Retrofitting of Old Ghari Ward
Calculation by Lumen Method
Retrofitting of Lighting system:
The lighting demands of hospitals are complex due to their round-the-clock nature and the effects of lighting on patients and staff. Lighting, however, abounds with opportunities for energy savings.
Commercially available, cost-effective lighting technologies offer the best opportunities to achieve high energy savings and reduce hospital operations and maintenance costs.
We have suggested LED lights for the new lighting design of Old Ghari Ward so that
we can have reduced the consumption of electricity up to substantial percentage and make this old ward an energy efficient ward. We
LED lights uses less than a third of the energy consumed by fluorescents (140 kWh) and seven times less than incandescent (350 kWh). Requires less maintenance and the lifespan of LEDs is 50,000 hours, or around six years, when operated 24/7. This compares with a lifespan of about a year for fluorescent lamps and less than a year for incandescentlamps.1 reducing replacements cuts maintenance costs.
• Consolidate lamp inventories by eliminating unnecessary bulb types (different bulbs with the same purpose).
• Maximize matte or diffuse light-colored surfaces to encourage effective glare-free day lighting.
• Adopt a lighting strategy for a facility that can be integrated into future designs. A strategy should standardize technologies, apply control measures consistently (e.g., dimming, occupancy sensors, day lighting), and ensure a consistent look and feel throughout the hospital.
4. Results and Discussions
Before installation of LED lights, the Ghari Ward of Mayo Hospital was installed with 25 traditional bulbs with lighting load of 6750 KWh. This load is not up to the level of usage. To achieve the recommended illumination level
and energy savings through an efficient lighting design and use of LEDs; these conventional bulbs were replaced with LED lights with lighting load of 12000 KWh. The wattage of luminaries and installation cost and the payback period of LED bulbs is shown in Table 3.
Before installation of LED lights, the East ward in Surgical Tower of Mayo Hospital was installed with localized general lighting. The load of these lights are more than the required load in standards. To achieve the recommended
illumination level and energy savings through an efficient lighting design and use of LEDs; these lights were replaced with LED lights. The wattage of luminaries and installation cost and the payback period of LED bulbs is shown in
LEDs are the future technology which are highly promoted for their long life, energy efficiency, low energy consumption and ease of use in new and improved designs. They have the potential to save energy. Case study for Mayo hospital, a commercial building is being carried out and local lights are replaced with LEDs which give the 92160 KWh energy saving per year and gives the payback period of 3 years & 8 months with Rs. 122,880 cash flow. This result shows that the LED bulbs are best recommended for general lighting and can be replaced in place of traditional local lights. These lights have higher installation cost but this can be compromised as
they have more energy saving and reduced payback period.