A research study by Dani Soares and Kevan Shaw

Abstract

This research seeks to identify the most suitable LED lamp for the comprehensive replacement of obsolete halogen systems, emphasizing color temperature and illuminance requirements. Focusing on two prevalent lamp types, G9 and E14/E27, our study investigates the perceived and measured color temperature of LEDs under both trailing and leading edge control systems. Given uncertainty about the existing control system, our approach encompasses both, ensuring relevance for future decision-making.

Through rigorous experimentation, LED lamps underwent testing to measure color temperature and illuminance, evaluating their efficacy as halogen replacements. Theoretical considerations propose that trailing edge control

demonstrates superior efficiency in modulating illuminance by their ability in controlling lower wattage loads. On the contrary, leading phase dimming are more suitable to incandescent and halogen lamps due to their predominant resistive load technology rather than capacitive or inductive.

Results reveal distinctive responses under trailing and leading edge control, providing practical insights into selecting LED lamps for the complete replacement of halogen systems, considering both G9 and E14/E27 options. The dual consideration of control systems ensures adaptability to varying technological landscapes, facilitating informed decisions in transitioning to energy-efficient lighting systems.

Introduction

In the pursuit of energy-efficient lighting solutions, the evolution of Light Emitting Diodes (LEDs) stands as a cornerstone, promising both sustainability and enhanced performance. As the global shift towards greener technologies accelerates, the replacement of obsolete halogen systems with advanced LED counterparts becomes imperative. This research endeavors to navigate the intricate landscape of LED technology, specifically addressing the selection dilemma between G9 and E14/E27 lamp types, with a nuanced focus on color temperature and illuminance.

Halogen lighting systems, once pervasive, now face obsolescence due to their inefficiency and environmental impact. LED lamps emerge as a compelling alternative, boasting longevity, energy efficiency, and reduced environmental footprint. However, the varied characteristics of G9 and E14/E27 lamp types pose a challenge in determining the optimal replacement for halogen counterparts.

The color temperature and illuminance of lighting systems play pivotal roles in shaping the ambiance and functionality of a space. To address this, our research embarks on a comprehensive analysis, considering not only the lamp types but also the influence of control systems.

Amidst this backdrop of technological evolution and theoretical considerations, our study aims to fill a critical gap by empirically evaluating the color temperature and illuminance of G9 and E14/E27 LED lamps. The ambiguity surrounding the control system—whether trailing or leading edge—adds a layer of complexity that necessitates a thorough investigation, ensuring the relevance of our findings for future decision-making.

By shedding light on the nuanced interplay between LED technologies, lamp types, and control systems, this research aims to guide the transition from halogen to LED lighting systems. In doing so, it contributes not only to the field of lighting technology but also to the broader discourse on sustainable and efficient energy consumption.

Methodology

1. Selection of LED Lamps:

The selection process commenced by identifying LED lamps that exhibit consistent illuminance and perceived color temperature outputs across various dimming levels. Emphasis was placed on ensuring the quality and stability of performance throughout the dimming range for all lamps, spanning from G9 to E14/E27.

For G9 LED lamps, the following models were selected:

Paulmann LED G9 2000 to 3000k

Unbranded G9-COB-3WD 2200 to 2800k

Unbranded LED Bulb G9 3W 2700 to 3200k

Crompton LED G9 Sunset Dim 3w 2800k - 2200k

For E27 LED lamps, the following models were chosen:

Tala Sphere I
Tungsgram 2000-2700K
Zico A60 GLS Clear
Zico A60 GLS Porcelain

Additionally, E14 LED lamps were included:

E14 Integral LED 1800 - 2700K 6W
E14 Tala Sphere I dim to warm matte white

These selections were made to ensure a diverse representation of G9, E14, and E27 LED lamps, covering a range of color temperatures relevant to domestic and commercial settings.

At the conclusion of this initial phase, a meticulous selection was made, focusing on lamps that demonstrated superior consistency. This selection aimed to establish a pool of lamps suitable for further matching between G9 and Edison cap lamps.

Remarkably, only one G9 lamp successfully passed the rigorous criteria in the initial test— the Paulmann G9. This led to its inclusion as the representative G9 lamp for the subsequent phases of the study.

The subsequent phase involved attempting to match the chosen Paulmann G9 with all E14/E27 lamps through precise illuminance and color temperature measurements.

2. Experimental Setup:

The experimental setup was conducted within our office premises, ensuring a controlled environment conducive to accurate measurements of color temperature and illuminance.

The tools and measurement equipment utilized for this study were exclusively sourced in-house.

LED lamps, including the Paulmann G9, E14, and E27 lamps, were installed in standardized fixtures, replicating conditions typical of home or commercial settings.

The control panel used for the experiments included a mode-lighting control panel, specifically an eDin+ 4x3A Leading Edge Dimmer Din-03-04-Plus, and an eDin+ 4x2A Trailing Edge Dimmer Din-02-04-Te-Plus.

The control panel allowed seamless transitions between leading and trailing edge control systems, providing a comprehensive evaluation of the lamps’ performance under different conditions.

3. Measurement Instruments:

The measurement tool employed for this study was the Asensetek Lighting Passport, paired with the appropriate SGM app.

During the initial testing phase, we relied solely on visual observation without the use of any tools. This phase aimed to assess our subjective perception of color temperature and illuminance, emphasizing the consistency between two bulbs of the same model, rather than seeking precise measurements.

Calibrated light meters were used for accurate measurement of illuminance levels, ensuring reliable and precise data collection.

4. Data Collection:

In the first phase, perceived color temperature and illuminance levels were assessed visually, relying on human perception rather than measurement tools. The focus was on the consistency between two bulbs of the same model. In subsequent phases, systematic testing of each G9, E14, and E27 LED lamp was conducted under both trailing and leading edge control systems relying on the tools previously mentioned.

Measurements were recorded at various dimming levels, from 0 to 100% in close intervals, to capture the dynamic range of each LED lamp.

5. Data Validation / Limitations:

Repeated measurements were consistently conducted in alignment with subjective assessments from the initial testing phase and throughout the entirety of the data collection process.

In the initial testing phase, reliant on visual observation without tools, subjective assessments on perceived color temperature and illuminance were provided for both bulbs of the same model. This qualitative assessment serves as a valuable reference point for validating the later quantitative measurements.

Figure 1 highlights a specific case where inconsistencies in measurements were detected, potentially attributed to a faulty bulb. This underscores the importance of cross-verification and the necessity of addressing anomalies in the data.

The ambient lighting conditions were ideal, with the background lighting in the enclosed space nearly reduced to zero.

Through the meticulous implementation of this methodology, the study aims to generate robust data on the color temperature and illuminance characteristics of the specified G9, E14, and E27 LED lamps under different control systems, contributing valuable insights to the broader discourse on sustainable lighting solutions.

Figure 1 shows the data collected for the E27 Zico A60 GLS Clear after our first visual assessment. After an initial swap to identify the source of the discrepancy, we can infer that most likely we were dealing with afaulty LED bulb. (Grey)

Results - Consistency

G9 Consistency

Perceived Color Temperature and Illuminance.

Method: Visual Assessment

Measurements were conducted with a focus on the selected G9 lamps for this project. Notably, a notable level of inconsistency was observed across the chosen lamps, primarily stemming from a lack of color temperature uniformity. Additional notes include:

For the G9-COB-3WD lamps, a swap was implemented, and the subsequent results exhibited consistency with the initial findings. This adjustment aimed to discern whether the issue lay with the control panel or the lamp itself.

Regarding the LED BulB G9 3W, it presented a close match to the previous model, but a discernible pink tone emerged from 30% brightness onwards on L2.

The Crompton model displayed a significant difference, leaving little room for doubt.

In the case of the Paulmann model, despite a slight tone difference (Red) at L2, the match remained reasonably consistent across all dimming levels.

The Model chosen for the next phase was the Paulmann G9.

E27 Consistency

Perceived Color Temperature and Illuminance.

Method: Visual Assessment

In the case of the E27 models, measurements were conducted following the methods employed in the initial phase. Unlike the assessed lamp type discussed earlier, it is evident that there is a notable and consistent level of uniformity across all models.

All the models were subsequently considered for the next phase.

E14 Consistency

Perceived Color Temperature and Illuminance.

Method: Visual Assessment

In the case of the E14 models, measurements were conducted following the methods employed in the initial phase. Tala’s results, although consistent in terms of illuminance, it showed clear color temperature distinction between the two lamps. On the other hand, Integral LED showed good consistency from the 1% dimming level, being the only lamp capable of operating at such low levels.

Only Integral LED was considered for the next matching phase.

Results - Leading Edge Match

Control System: Leading Edge

Matching Test G9 - E27 - E14

Measured Color Temperature (K) and Illuminance (lux).

Method: Asesentek Lighting Passport

Results - Trailing Edge Match

Control System: Trailing Edge

Matching Test G9 - E27 - E14

Measured Color Temperature (K) and Illuminance (lux).

Method: Asesentek Lighting Passport

Discussion

All the products available in the replacement lamp category are primarily intended for domestic use. As such they are designed to meet competitive cost targets, and this seems to be the primary consideration over quality and consistency from product to product or batch to batch. This testing has been undertaken in consideration of using these lamps in commercial spaces, particularly hospitality where significant numbers are used together in the same space inviting visual comparison. The lamps tested were chosen on a quality / availability basis at the higher quality end of the market based on the retail prices of the products. Using Lamp replacement products is never a first choice. It is forced by the choice of, predominantly, decorative fittings by interior designers and the unwillingness of the producers of these fittings to engage with the complexities of LED technology.

The other aspect is the continuing use of lighting control systems and wiring with technology designed for power control of incandescent lamps. This system cuts the sine wave to reduce the power provided either by late switch on, leading edge, or early switch off trailing edge during each cycle. This works well for a resistive load such as incandescent but is disruptive for either capacitive loads, typical of most LED drivers or inductive loads such as wire wound transformers. Where minimal cost circuits are trying to control not only intensity but colour temperature as well, this becomes overwhelmingly challenging as we have demonstrated in this report.

Conclusion

The use of warm dim lamp replacement products is a conjunction of compromises that will result in lower quality lighting than that formerly provided by incandescent sources. The products are relatively expensive and as they will compromise the lit experience of the space and sometimes the appearance of expensive decorative fittings. Thought should be given as to whether the potential energy saving is worth it, at least while incandescent lamps are still available in the market.

Maintaining any visual consistency between fittings and spaces will require more work in visually setting up the lighting control system. Ultimately choices will need to be made between consistent colour appearance and consistent light levels. The variability of appearance between different lamps2 of the same batch further requires over ordering of lamps to allow any particularly visibly different lamps to be swapped out.

Ultimately, avoid using light fittings that use legacy lamp holders requiring lamp replacement technology and specify fittings that are designed around dedicated LED light sources.

Considering the data collected, it is our assessment that achieving an exact match may not be feasible. However, a reasonably close pair for consideration is the Paulmann G9 with the E27 Tala Sphere I LED bulb. This pairing demonstrates a minimal standard deviation of (-1.75%) compared to the closest alternative (20.25%) with the E27 Zico Porcelain LED.