The original ARC highbay luminaire from Nualight was one of the first highbay fixtures to shift to a radical new approach in luminaire design, whereby the luminaire housing became the primary heatsink for the LED source. This was a shift away from the conventional box form or spun reflector, which were designed for high-intensity discharge lamps.
The re-design within Arc 2 appears subtle, yet the new luminaire provides a profound improvement over the original fixture. At first sight, the Arc 2 housing and heatsink is the same as its predecessor, but the cooling performance provided by the airflow through the housing has been re-visited, resulting in a far better control of temperatures within the luminaire components.
As well as the improved efficiency of the housing and heatsink design, there are other changes:
- The rear-mounted driver housing is shorter, so lighter
- The number of internal components has been reduced
- The material specification of the body has been upgraded to marine grade LM6 aluminium
- The LED array has been altered to provide better uniformity, light output and visual comfort
- There is a measurable improvement in reduced temperatures within the internal components
- The reduced complexity in the design has improved assembly and delivery times
The scale of the improvements can be seen in the performance figures:
Of course, the situation on the ground will still see value propositions being requested that compare new LED highbay lighting against conventional metal halide luminaires. With this level of improvement in LED performance, the difference between old and new technologies is even more stark.
Comparing metal halide with Arc2 LED:
Looking at two equivalent scheme designs side-by-side, assuming annual hours in use of 3000 hours and an electrical running cost of £0.15 /kWh. Its assumed that the lifetime of the installation will be 20 years.
Scheme profile – performance data
Return on Investment
At 20 years, we assume a complete luminaire replacement in both cases.
Because of the better efficacy of the LED luminaire, the number of Arc2s required is only 60 percent that of the metal halide units. This means that the initial purchase and installation of the luminaires already favours the LED technology, offering a £4000 reduction in capital expenditure between the two options, despite the higher unit cost of the Arc2 luminaire.
The simple fact is that, from the first moment of switch-on, the LED option starts to save money.
Having saved £4000 on the initial installation, the more efficient ARC2 continues to save money for the business to the tune of £1,000+ per year.
Significant improvements available from Arc2 and LED technology
The impact of the improved LED design goes beyond the amount of light that is generated. Many LED highbay fixtures are offered with an L70 figure of 50,000 hours. By comparison, the LEDs used within ARC2 produce TM-21 figures that report a lumen maintenance figure of >0.95 at 36000 hours, enabling the company to confidently predict a practical L90 figure at +50,000 hours.
Nualight performance data states an L90 figure of 100,000 hours. Strictly speaking, this goes beyond the ‘officially permitted’ data extrapolation of six times the test period (6000 hours in the case of the LEDs within ARC2), but it is in keeping with commercial claims from other companies. In practice, a 100,000 hour life period is in excess of thirty years and is unlikely to be experienced in the real world. Hence, this Value Proposition has concentrated on the lumen maintenance of the luminaire across 50,000 hours.
Andrew Cronin, VP of Product Research and Development told Lux: ‘LM80 and TM21 used in conjunction with In-Situ Temperature Measurement Testing (ISTMT) is the only sensible approach to judging quality or life predictions of LED products. I can say that Nualight does consider and measure this data accurately to ensure our lifetime data is correct..
Explainer: ISTMT is a measurement of the LED source case temperature within the luminaire or lamp while it is operating in its designed position and environment. The measurement is performed at the temperature measurement point indicated by the LED package manufacturer. It provides the basis for lifetime interpolation based on TM-21-11 calculations (and other approved methods)
From a long-term maintenance point of view, and based on 3000hours per year usage, this provides a useful life of the luminaires of around 20 years, without the need for ‘over-lighting’ in the design to compensate for light loss during that period.
Lumen maintenance is a vital aspect of LED luminaire design. Given the longevity of the LED source, any light loss during life must be compensated for within the initial design. An L70 figure at 50,000 hours suggests that the design illuminance needs to be increased by 30 percent in order to compensate for light loss during the operating life of the installation.
Explainer: L70 refers to the time that it takes for the amount of light generated at the beginning of a luminaire’s life to fall to 70% of the original output. Similarly, L90 refers to a 10% reduction in lumen output over the stated time.
A lot of light can be wasted if an inappropriate optical design is used in areas containing warehouse racking. ARC2 offers a wide beam option, for open areas, and a specially-designed ’aisle’ optic for lighting within high racking.
Controlling the output
Arc2 is available with sensors: PIR presence detectors, daylight sensing and DALI-dimming can all be provided to ensure that energy is only consumed when it is required, making ARC2 an ideal fixture to use in conjunction with buildings with rooflights and where areas may only be accessed occasionally.
A case study
Nualight undertook a study of the effectiveness of sensor controls in one of their installations. The findings lead incontrovertibly to the conclusion that sensor control is a valuable addition to any energy management proposals.
The case study took place at a mixed-use site with twelve large sheds. Some buildings are in use for 12 hours, other for 8 hours per day. The Nualight LED installation replaced a mix of fluorescent (T5 and T8 tubes) and metal halide luminaires.
Roof area: 30,000m2
Area of roof taken up by polycarbonate roof lights: 7 percent
Annual lighting costs before the new LED installation: £46,000.00
Expected changes via improved lighting technology only: 60% (£27,600 saving on annual costs)
Result of the inclusion of sensor controls:
Savings achieved in lighting costs per year: 91 percent (£41,860 saving on annual costs)
Return on Investment: 3.2 years