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Scope

1.1 This Greenfit Building Code Standard (GBCS) establishes guidelines and requirements for the design, construction, and evaluation of indoor spaces to ensure that there is sufficient natural light for the growth and sustenance of average plant life.

1.2 The purpose of this standard is to promote and facilitate the growth of plants indoors, contributing to healthier indoor environments, improved air quality, and enhanced well-being for occupants.

Terminology

2.1 Greenfit: A certification indicating that a building or space meets the requirements for sufficient natural light to support average plant life throughout the space.

2.2 Average Plant Life: Common indoor plants that require moderate levels of sunlight for growth and survival, such as pothos, spider plants, and snake plants.

2.3 Low Light Plants: Indoor plants that can thrive with minimal natural light, such as ZZ plants, snake plants, and pothos.

2.4 Medium Light Plants: Indoor plants that require moderate levels of sunlight, such as spider plants, philodendrons, and peace lilies.

2.5 High Light Plants: Indoor plants that need ample sunlight, such as fiddle leaf figs, succulents, and citrus trees.

2.6 Lux: a unit of measurement for illuminance, which quantifies the amount of visible light that reaches a surface per unit area. One lux is equivalent to one lumen per square meter, allowing for the assessment of light levels in various environments, from natural daylight to artificial lighting.

2.7 Foot-candles: a unit of measurement for illuminance, representing the amount of visible light that reaches a surface per unit area in the Imperial system. One foot-candle is equivalent to one lumen per square foot, and it is used to assess light levels in indoor and outdoor environments.

2.8 Lumens: a unit of measurement for luminous flux, quantifying the total amount of visible light emitted by a light source in all directions. This metric helps evaluate the brightness of light sources, such as light bulbs, and is used to assess the adequacy of lighting in various environments.

2.9 Photosynthetic Photon Flux (PPF): a measurement of the total amount of photosynthetically active radiation (PAR) emitted by a light source per second, expressed in micromoles per second (μmol/s). It quantifies the light energy available for photosynthesis in plants and helps evaluate the effectiveness of light sources for plant growth.

2.10 Daily Light Integral (DLI): a metric that quantifies the cumulative amount of photosynthetically active radiation (PAR) a plant receives during a day, expressed in moles of photons per square meter per day (mol/m²/day). DLI helps determine the light requirements for various plant species and assesses the adequacy of light for optimal plant growth in indoor and outdoor settings.

2.11 Daylight Factor (DF):a metric that quantifies the amount of natural light available in an indoor space, expressed as a percentage of the outdoor illuminance under overcast sky conditions. It helps assess the effectiveness of daylighting design and the distribution of daylight within a building.

2.12  Daylight Autonomy (DA): a performance metric that measures the percentage of annual occupied hours during which a space can maintain a target illuminance level using only natural daylight, without relying on artificial lighting. It evaluates the effectiveness of daylighting strategies and promotes energy-efficient design in buildings.

2.13 Spatial Daylight Autonomy (sDA): a metric that evaluates the percentage of a space’s floor area that receives a minimum target illuminance level from natural daylight for a specified portion of the annual occupied hours. It helps assess the distribution and effectiveness of daylighting strategies throughout a building’s interior spaces.

2.14 Annual Sunlight Exposure (ASE): a metric that quantifies the amount of direct sunlight received by a space’s floor area over the course of a year, typically expressed in hours per year. It helps assess the potential for excessive sunlight, glare, and solar heat gain, informing strategies for shading and energy-efficient design in buildings.

Design Requirements

3.1 Building Orientation: Building orientation should optimize natural sunlight exposure for the interior spaces.

3.2 Window-to-Floor Area Ratio (WFA): A minimum WFA of 20% shall be maintained to ensure sufficient natural light penetration. The WFA is the total window area divided by the total floor area of the space.

3.3 Glazing: Windows shall have a minimum Visible Light Transmittance (VLT) of 70% to maximize the penetration of natural light.

3.4 Daylighting Controls: Buildings should include daylight-responsive lighting controls to minimize energy consumption while maintaining adequate light levels for plant growth.

3.5 Artificial or supplemental plant lighting: electric light sources, such as LED, fluorescent, or HID lamps, which provide the necessary spectrum and intensity of light for plant growth and development in the absence of, or as a supplement to, natural sunlight.

Certification Levels and Requirements

4.1 Bronze Certification: Buildings that meet the minimum requirements for supporting low light plants.

4.1.1 Lux: The minimum average lux level for Bronze certification is 100 lux.

4.1.2 Foot-candles: The minimum average foot-candles level for Bronze certification is 10 foot-candles.

4.1.3 Lumens: The minimum average lumens per square meter for Bronze certification is 500 lumens.

4.1.4 Photosynthetic Photon Flux (PPF): The minimum average PPF for Bronze certification is 100 μmol/m²/s.

4.1.5 Daily Light Integral (DLI): The minimum average DLI for Bronze certification is 5 mol/m²/day.

OR,

4.1.6 Daylight Factor (DF): The minimum DF for Bronze certification is 1.5%.

4.1.7 Daylight Autonomy (DA): The minimum DA for Bronze certification is 30%.

4.1.8 Spatial Daylight Autonomy (sDA): The minimum sDA for Bronze certification is 30%.

4.1.9 Annual Sunlight Exposure (ASE): The maximum ASE for Bronze certification is 20%.

4.2 Silver Certification: Buildings that meet the requirements for supporting medium light plants.

4.2.1 Lux: The minimum average lux level for Silver certification is 200 lux.

4.2.2 Foot-candles: The minimum average foot-candles level for Silver certification is 20 foot-candles.

4.2.3 Lumens: The minimum average lumens per square meter for Silver certification is 1,000 lumens.

4.2.4 Photosynthetic Photon Flux (PPF): The minimum average PPF for Silver certification is 200 μmol/m²/s.

4.2.5 Daily Light Integral (DLI): The minimum average DLI for Silver certification is 10 mol/m²/day.

                OR,

4.2.6 Daylight Factor (DF): The minimum DF for Silver certification is 2.5%.

4.2.7 Daylight Autonomy (DA): The minimum DA for Silver certification is 50%.

4.2.8 Spatial Daylight Autonomy (sDA): The minimum sDA for Silver certification is 55%.

4.2.9 Annual Sunlight Exposure (ASE): The maximum ASE for Silver certification is 25%.

4.3 Gold Certification: Buildings that meet the requirements for supporting high light plants.

4.3.1 Lux: The minimum average lux level for Gold certification is 500 lux.

4.3.2 Foot-candles: The minimum average foot-candles level for Gold certification is 50 foot-candles.

4.3.3 Lumens: The minimum average lumens per square meter for Gold certification is 2,500 lumens.

4.3.4 Photosynthetic Photon Flux (PPF): The minimum average PPF for Gold certification is 400 μmol/m²/s.

4.3.5 Daily Light Integral (DLI): The minimum average DLI for Gold certification is 20 mol/m²/day.

                OR,

4.3.6 Daylight Factor (DF): The minimum DF for Gold certification is 4%.

4.3.7 Daylight Autonomy (DA): The minimum DA for Gold certification is 70%.

4.3.8 Spatial Daylight Autonomy (sDA): The minimum sDA for Gold certification is 75%.

4.3.9 Annual Sunlight Exposure (ASE): The maximum ASE for Gold certification is 30%.

Measurement and Certification Process

4.1 A qualified professional shall assess the space against the GBCS requirements, including lux, foot-candles, lumens, PPF, DLI, DF, DA, sDA, and ASE measurements.  Upon successful verification, the space shall be awarded Greenfit certification.

4.2 Upon successful verification, the space shall be awarded the appropriate Greenfit certification level—Bronze, Silver, or Gold.

Maintenance and Renewal

5.1 Greenfit-certified spaces shall be subject to periodic inspections, at least once every three years, to ensure continued compliance with the GBCS.

5.2 If modifications are made to the space that could impact natural light levels, a re-evaluation by a qualified professional is required to maintain Greenfit certification.