Comparing LED and HID Horticultural Luminaires

June 11, 2018

An evaluation of the energy and economic performance of LED horticultural luminaires compared with high-pressure sodium (HPS) and metal halide (MH) horticultural luminaires has found that the LEDs cannot replace HPS luminaires on a one-for-one basis while still maintaining the original photosynthetic photon flux density (PPFD).

The evaluation was conducted by the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute, and funded in part by Natural Resources Canada. Based on findings from a literature review and online survey conducted by the LRC in 2016, the project team developed a framework for evaluating and comparing horticultural luminaires. The framework includes recommended testing, evaluation, and reporting methods. It allows luminaires to be compared based on equal PPFD. PPFD for plants is analogous to photopic illuminance on a work surface in an architectural application. The framework includes an analysis of 11 luminaire-specific metrics and 5 application-specific metrics, which provide growers with the best available information regarding any given horticultural luminaire’s performance. 

The LRC then used this framework to test and evaluate 13 horticultural luminaires, including 10 LED, 2o HPS, and one MH product.* First, the LRC photometrically tested individual luminaires. Then the LRC modelled the use of the luminaires in a simulated greenhouse to assess the number of luminaires and the lighting system energy requirements necessary to reach minimum PPFD and uniformity criteria. 

The results show that intensity distribution plays an important role, illustrated by the fact that two of the tested LED luminaires had higher luminaire efficacy than the HPS luminaires but still had a higher total power demand in the greenhouse application. 

The LRC found an increase in shading from LED luminaires compared with HPS luminaires due to the size of the luminaires and the fact that more are needed to provide the same PPFD in a greenhouse. The shading from LED luminaires reduces daylight in a greenhouse by 13% to 55% compared with a 5% reduction in daylight from HPS luminaires, thus more electric energy could be needed for lighting with the LED systems, depending upon the available daylight. 

The greater number of LED luminaires and their equivalency, on average, in application power demand impacted their life-cycle costs. The LRC found that three of the tested LED horticultural luminaire lighting systems had lower life-cycle costs and the remaining seven had higher life-cycle costs than either of the two 1000-watt HPS lighting systems that were tested. 

The results of the evaluation show that stakeholders can be misled by considering luminaire efficacy alone. Rather, the luminaire intensity distribution and layout to reach a criterion PPFD are necessary for an accurate life cycle cost analysis. The LRC report provides a technology-neutral framework that stakeholders can use to evaluate lighting systems. 

The project was funded by the Lighting Energy Alliance and Natural Resources Canada. Members of the Lighting Energy Alliance include Efficiency Vermont, Energize Connecticut, National Grid, and the Northwest Energy Efficiency Alliance.

View the report

This article is a lightly edited version of the report’s introduction.

Photo source: Philips Lighting

* The results in this report are based on electrical and photometric testing of one luminaire sample per model. Life testing was not conducted for this project. No crops were grown or evaluated with any of the tested luminaires.

Related Articles


Changing Scene

  • LEDVANCE Expands Ontario Presence with New Specification Agent

    LEDVANCE Expands Ontario Presence with New Specification Agent

    LEDVANCE is pleased to announce the appointment of Sterling Architectural Products Ltd. (Sterling Lights) as their new specification agent in Ontario. This partnership strengthens LEDVANCE’s presence in the region and reinforces their commitment to serving the professional lighting design and specification community with innovative, reliable lighting solutions. With decades of experience and a service-driven mindset,… Read More…

  • May 29, 2025 - Eureka Wins Three 2025 Red Dot Awards for Product Design

    Eureka Wins Three 2025 Red Dot Awards for Product Design

    Eureka is pleased to announce that its Velia, Cirra, and Junction luminaires have each received a 2025 Red Dot Design Award for Product Design. It is the 11th consecutive year that Eureka products have been honored with this prestigious award, which is a testament to the company’s consistency and relentless drive to design exceptional luminaires.… Read More…


Design

  • The Difference Between Accent, Ambient & Task Lighting: Ultimate Guide

    The Difference Between Accent, Ambient & Task Lighting: Ultimate Guide

    In interior design, lighting is not just about brightening the room. Sensitive lighting layout is the key in the whole aesthetic atmosphere. An outstanding lighting solution will not rely on one type of fixture. Rather, it is through the combination of different types of lighting. Accent, ambient, and task lighting are three basic types of… Read More…

  • Graphic Office Interiors Enhance Their Office Space, Incorporating State-Of-The-Art Lighting Solutions

    Graphic Office Interiors Enhance Their Office Space, Incorporating State-Of-The-Art Lighting Solutions

    Graphic Office Interiors, a renowned office design and furnishings company serving Vancouver Island since 1966, embarked on a unique lighting project for their personal office in Saanichton, BC. This project marked the first collaboration between Kelly Inglis of Mac’s II Agencies and Graphic Office Interiors’ in-house registered interior designer, Laura Harlos. Known for their exclusive Steelcase furniture line, modular moveable… Read More…


New Products

  • Eureka Announces New Accessories for Scout Luminaire

    Eureka Announces New Accessories for Scout Luminaire

    Eureka has announced the enhancement of its Scout luminaire family with the introduction of new accessories and a new color palette. Three new diffusers have been introduced. Bell is minimalist, translucent and cloche-shaped. Pebble introduces a soft touch and an ambient glow in a distinct, oval-shaped diffuser. Orb is sleek and dome-shaped, adding a touch… Read More…

  • Amico: SOLAR ECLIPSE – 2X4 Multi-Functional Luminaire

    Amico: SOLAR ECLIPSE – 2X4 Multi-Functional Luminaire

    The Solar Eclipse Series provides a multi-functional luminaire that supports the demands of the hospital environment. The sleek and modern design merges architectural aesthetics with exceptional lighting performance to improve patient comfort while maximizing clinical efficiencies. This architectural patient room fixture offers reading, ambient, and exam functionalities and an optional night light. Multi-functional capabilities provide… Read More…