This page is about the development of the lighting plan for the Duplicable City Center. It is purposed to share the important developments and considerations made in relationship to the interaction of light, energy conservation, and aesthetics in this structure. This page includes the following sections:
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Designing an eco-lighting plan means creating a maximally energy efficient and functional plan to meet all of a structure’s lighting needs. It saves energy and reduces up-front energy infrastructure costs in off-grid village construction. As a component of achieving LEED Platinum certification, lighting is also a big foundation of 25 possible points of 80 needed (out of a total of 110) for LEED Platinum qualification.
One Community’s goal in open sourcing the Duplicable City Center eco-lighting plan is to help people interested in more sustainable lighting approaches, saving money through reduced energy usage, and/or curious about the process of maximizing lighting-related points for LEED Platinum certification. These goals are also part of our Highest Good Energy plan for do-it-yourself and replicable teacher/demonstration communities, villages, and cities.
Eco-lighting can be designed using several different approaches. We’ve used the Leadership in Energy and Environmental Design (LEED) guidelines as our foundation. We discuss here the specifics of LEED, how you can apply these eco-lighting standards to your own projects, and our LEED Platinum design process for the Duplicable City Center. We do this with the following sections:
LEED is a third-party certification program and the nationally accepted benchmark for design, construction, and operation of high-performing sustainable buildings. LEED gives the owners the performance metrics needed for improving the holistic aspects of energy efficiency in their buildings. LEED also promotes a whole-building approach to sustainability. It does this through five key areas: sustainable site development, water savings, energy efficiency, materials selection, and indoor environmental quality.
The lighting aspects of LEED are emphasized in the energy efficiency and the indoor environmental quality sections. LEED Version 4 (the most current as of this writing) promotes more energy efficient lighting and lighting design with the following credited areas:
Here we discuss each of the areas where LEED points can be awarded in association with lighting. As previously mentioned, 25 points are possible with sustainable energy management and 80 points are needed (out of a total of 110) if LEED Platinum status it to be achieved. Lighting is a significant part of these 25 points. We discuss here the details of the various areas where points are awarded in a way we hope will help anyone interested in improving the sustainability of a structure. Regardless of whether or not you are interested in actual LEED certification, applying the strategies below will make your building more energy efficient and sustainable.
Under the Energy and Atmosphere section, as a minimum prerequisite (not for points), LEED requires a 5% overall energy reduction above the 2010 ASHRAE baseline standard for new construction. So while the ASHRAE 2010 standard provides the minimum requirements for energy-efficient design of buildings, the proposed design has to be done using the whole-building energy simulation method (using a software) and show a 5% overall reduction beyond this standard. At 6% reduction, one point is awarded – all the way up to 50+% reduction where 18 points are awarded. The prescriptive lighting density allowances do not need to be complied with if using energy modeling to demonstrate compliance for LEED. Only the mandatory provisions should be met to demonstrate compliance.
If the building owner decides not to use the whole building simulation method, he can choose to instead meet the Prescriptive Compliance Path of the ASHRAE 50% Advanced Energy Design Guide. This requires meeting both the mandatory and prescriptive provisions of ASHRAE 2010 standard. To achieve this, interior lighting requirements are divided into a set of mandatory requirements, provisions that must be complied with regardless of the quantity of lighting that is installed, and two prescriptive methods for determining the allowed wattage for the building: whole-building and space-by space.
Standard 90.1-2010 requires the following mandatory lighting controls:
Through its prescriptive requirements, ASHRAE/IES 90.1-2010 additionally imposes limits on the amount of lighting power installed in the building. This is measured in watts per square foot (WPSF) to promote efficient technology and design. As stated above, designers have a choice of using the Building Area Method (whole building power allowance) or Space-by-Space Method (individual spaces).
When using the Space-by-Space Method of compliance with the standard’s prescriptive lighting power allowance requirements, Standard 90.1-2010 offers lighting power adjustment credits based on use of advanced lighting control strategies in certain offices, meeting spaces, education spaces, retail sales areas, and public spaces. Qualifying technologies range from manual dimming control to much more complex and specific automatic continuous daylight harvesting dimming with power adjustment factors (applied to the controlled lighting load of 5-30%).
Building Area Method is mainly used for projects where the entire building is for one primary use and/or for single-occupancy types of buildings. Space-by-space is more flexible and is used if the building has multiple occupancies/spaces. Space-by-space method is often used in these situations because it allows trade-offs between spaces because it compares the total specified lighting wattage for the entire building to the sum of space-by-space allowances.
This article: “ASHRAE Releases 90.1-2010–Part 1: Design, Scope, Administrative Requirements” is an excellent resource for understanding this better. It also includes an informative chart showing how the various wattage allowances have evolved over the years.
The Energy and Atmosphere for Optimizing Energy Performance credit can be as high as 18 points if total-building energy modeling is performed. The objective of this credit (of which lighting is only a small part) is to increase the level of total energy performance beyond ASHRAE 2010 standards. One point can be achieved by showing a minimum of a 6% increase in the proposed building energy performance compared to ASHRAE 2010 standards. The maximum of 18 points can be achieved if a 50% (or more) increase is shown above ASHRAE 2010 standards.
The other choice is to simply meet the prescriptive requirements of ASHRAE Advanced Energy Design Guide for your specific structure type: Small-to-Medium Office Building, Medium-to-Large Retail Building, K-12 School, or Large Hospital. Without a whole-building energy analysis though, this only awards 1-2 points.
To help people desiring maximum efficiency (and points), the Advanced Energy Design Guides provide prescriptive energy savings guidance and recommendations by building type and geographic location. These are design packages and strategies to help owners and designers achieve 50%+ site energy savings over ASHRAE Standard 90.1 2010. There are four AEDG guides:
So conducting a whole-building energy analysis and demonstrating 50% efficiency increase above ASHRAE 2010 standards shows that you are not only focused on lighting, but all areas where energy savings are possible. The ASHRAE Advanced Energy Design Guide provides a path to meeting the 50% efficiency increase above ASHRAE 2010 goal. The whole-building energy analysis confirms the results so appropriate points can be awarded.
The Indoor Environmental Quality Credit for Interior Lighting can award up to 2 points. One for “Lighting Control” and one for “Lighting Quality.”
For 90% or more of occupant spaces, the project must provide individual lighting controls that allows users to adjust the lighting to suit their individual tasks and preferences with at least 3 lighting levels (on, off, mid-level). Mid-level is 30% to 70% of maximum lighting levels. More levels than this though can be accomplished with dimmers, table lamps for work spaces with a mid-level setting, etc. The idea here being that a person should be able to use any space without turning on all the lighting for the room.
This choice features eight strategies, and you must include at least four of the following eight options in your project to get the related point.
The intent of this credit is to provide occupants a connection to outdoors through daylight and views from regularly occupied spaces. This reinforces circadian rhythms and reduces the use of electrical lighting by introducing daylight into the space. This can be done by providing manual or automatic (with manual override) glare control devices (such as Venetian blinds or adjustable louvers) for all regularly occupied spaces.
To qualify for these points, simulation or measurements are accepted and there are 3 methods LEED accepts (click here for a resource article about them all):
The intent of this credit is to provide quality views and giving occupants a connection to the outdoor natural environment. This can be done by providing vision glazing for 75% of floor area. “Vision glazing” is windows, or the portion of larger windows, that provide a connection to the outdoors. These are typically vertical windows between 2.5 ft and 7.5 ft above the floor. Also known as View Windows and not to be confused with Daylight Windows – windows designed to provide interior illumination and located above eye height (7.5 ft), or the portion of a window more than 7.5 ft above the floor.
To claim this point, you must include a direct line of sight to the outdoors via vision glazing for 75% of all regularly occupied floor area. View glazing in the contributing area must provide a clear image of the exterior, not obstructed by frits, fibers, patterned glazing, or added tints that distort color balance. Additionally, 75% of all regularly occupied floor area must have at least two of the following four kinds of views:
Include in the calculations any permanent interior obstructions. Movable furniture and partitions may be excluded.
Views into interior atria may be used to meet up to 30% of the required area.
Click here for the source resource for all of the above.
All LEED projects must comply with all applicable mandatory provisions of ASHRAE 90.1-2010. To meet the LEED “Optimize Energy Performance” prerequisite, it must also be demonstrated that there is an improvement in the proposed performance beyond the baseline rating as defined by ASHRAE 90.1-2010.
Prescriptive Compliance describes exactly what is required in terms of the design and performance of the building according to the ASHRAE 2010 standard. The designer has to follow exact instructions and not deviate or use their own approach. A prescriptive approach might make sense in a very simple building design, say with single HVAC, water, and lighting systems. The work associated with creating an energy model is not trivial, and the associated cost is not justifiable for many projects. In those cases, the reduced documentation requirements of the prescriptive-compliance path make more sense.
The alternative to a prescriptive path is a performance-based method where the architect or designer may have greater flexibility and freedom in designing the building but aims to achieve the same performance level, as demonstrated through a building energy simulation. If the energy-modeling compliance path is chosen, selection of mandatory lighting controls can help improve the model’s overall performance. LEED looks at the reduction in energy cost, not just energy usage, and encourages projects to use advanced modeling guidelines outlined in ASHRAE 2010 Appendix G.
The mandatory controls requirements of ASHRAE 2010 are relatively straightforward. They have to be met by both building simulation and the ASHRAE Advanced Energy Design Guides (AEDG) method. We discuss here all the areas related to these requirements.
ASHRAE/IES 90.1-2010 requires that all lighting systems be turned OFF when not in use. Controls may be either time-of-day, occupancy sensors, or a signal from another control or alarm system that indicates that the area is unoccupied. See our open source control and automation page for the specifics of how we’re addressing these requirements and much more.
The easiest way to satisfy this requirement is to put in occupancy sensors in areas like these:
The sensor must turn the lights OFF within 30 minutes of the space becoming unoccupied
In 90.1-2010, automatic shutoff controls must be manual-ON or automatically turn the lighting ON to not more than 50% power. Exceptions include public corridors and stairwells, restrooms, primary building entrance and lobby areas, and areas where manual-ON would endanger safety or security.
The lights in each enclosed space in the building must be independently controlled by a conveniently located manual control device or automatic occupancy sensor with manual-ON or auto-ON to 50% operation. The lighting must be configured for multiple levels enabling users to select at a minimum OFF, a step between 30% and 70% (inclusive) of full lighting power, and 100% of full lighting power. Stairwell lighting must be controlled so that lighting power can be reduced by at least 50% within 30 minutes of the stairwell space becoming unoccupied. Each control device shall also control no more than 2,500 sq ft for a space of 10,000 sq ft or less and a maximum of 10,000 sq ft for a space greater than 10,000 sq ft.
Main side-lighted areas directly adjacent to daylight apertures in an enclosed space that is 250 sq. ft. or larger require that the general lighting in that area must be separately controlled using either a stepped switching or continuous dimming controller. More aggressive daylight harvesting in primary and secondary side-lighted areas is rewarded with power adjustment credits. In top-lighted spaces, if the total daylight area under skylights plus the total daylight area under rooftop monitors is larger than 900 sq. ft., the general lighting must be separately controlled using either a stepped switching or continuous dimming controller.
ASHRAE/IES 90.1-2010 requires functional testing of lighting controls and systems, a service typically provided by the installing electrical contractor in a new construction project, and sometimes supervised by the designer or a commissioning agent. The standard requires that the construction documents identify who will conduct and certify the testing
The prescriptive control requirements have to be met only if path 2: ASHRAE 50% Advanced Energy Design Guides (AEDG) is chosen. ASHRAE/IES 90.1 imposes limits on the amount of lighting power installed in the building, expressed in watts per square foot, to promote efficient technology and design. Any new building design has to have lighting within the lighting power density limit. Designers have a choice of meeting the ASHRAE prescriptive requirements using the Building Area Method (whole building power allowance) or Space-by-Space Method (individual spaces, with potential additional and tradable allowances).
The Prescriptive Approach contains a look-up table to determine allowed wattage for each occupancy type. These tables are under the copyrights of the ASHRAE but can be found online by searching. Try searching for “ASHRAE Table 9.6.1” and see what you turn up. As a general guide, you’ll find wattage/ft2 ranging from a low .63 for areas like storage rooms, elevators, and stairways and highs around 1.2-1.6 watts/ft2 for areas like classrooms, workshops, “detailed manufacturing,” exhibit spaces, etc. Ranges of 1.8 to as high as 2.2 can be seen for areas like “courtrooms” and “retails sales areas” or “ring sports arena” or “emergency rooms” respectively.
The Building Area approach can be used for a single occupancy building or separate business entities within a building. The Space-by-Space approach is used for flexibility and for non-standard building types or space configurations.
This method is used for projects involving an entire building with a single, independent occupancy. The total connected lighting wattage is determined by multiplying the gross lighted area by lighting density factor according to the space type. Gross lighted area (GLA) includes basements, mezzanines and intermediate floor tiers, and penthouses, provided these spaces have a headroom height of 7.5 ft. or greater.
This method is applicable for a multiple occupancy building. The gross lighted area of the building is divided into each of the space types listed. The lighting power allowance is calculated by multiplying the area of space type by the lighting power density for that particular space.
The Building Area Method is sensitive to specific space functions and room configurations and is generally more restrictive. When a specific building type isn’t listed, “selection of a reasonably equivalent type” is permitted. The Space-by-Space Method is more flexible and is applicable to all building types. It accounts for actual room areas (e.g., lighting needs of enclosed office vs. open office) and an increase in the lighting power allowance is allowed for specific space functions.
The information on this page is meant for application by those seeking LEED Certification and also those just interested in improving their lighting efficiency and sustainability. With this in mind and based on all of our research and everything discussed above, here are our recommendations for applying what we’ve learned to achieve these goals. For new structures, here are our implementation suggestions listed from easiest to hardest:
LEED Certification guidelines can also be helpful for those interested in improving their lighting efficiency and sustainability in retrofit situations. Here are our implementation suggestions listed from easiest to hardest for retrofit scenarios:
LEED for the Duplicable City Center meets both the prescriptive and the mandatory requirements of ASHRAE 2010 as required by LEED. As discussed above, A LEED Platinum lighting plan looks at the maximum allowable light levels as a baseline and then performs an evaluation of the system you intend to build as a comparison to this maximum. New structures that incorporate a 48% (or more) increase in efficiency over the baseline are eligible for 25 (the maximum number) of LEED points for the energy usage/management category.
Our final design will demonstrate meeting these guidelines by using the Performance-based Energy Modeling method, so our energy usage rating will be for the entire building. This means that exceeding efficiency goals in one area can then provide additional energy availability in another area. Our goal, however, is to keep our numbers as low as possible because it reduces our total up-front energy infrastructure needs and costs.
We share here our complete design process with the following sections:
Before starting the detailed design process, we wanted to get a baseline for our ability to achieve LEED Platinum Certification. To do this, we first looked only at reducing our energy consumption. We chose this area first because we considered it one of the easiest to objectively evaluate and also one of the largest contributors to our overall carbon footprint and project sustainability. We used the following zones, square footages, and power density benchmarks from the Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE) as our starting point:
This would mean the following allowable watts per “zone” when using a 50% reduction (48% being the minimum needed for maximum points) as our goal:
We then made the assumption that we will exclusively utilize LED lights (click here for details), which have higher upfront costs but consume much less electricity than traditional or compact fluorescent bulbs. Here is how LEDs energy consumption compares to traditional lightbulbs to produce the same amount of light:
|LED Wattage||Traditional Wattage|
|4 W||25 W|
|8 W||40 W|
|10 W||60 W|
|20 W||100 W|
|30 W||150 W|
Assuming the use of 10W LEDs, we could very easily calculate an estimated lighting density for each area using this formula:
Wattage allowance for each area divided by 10 = # bulbs allowed. Total area divided by # of bulbs = estimated lighting density.
This produced encouraging results with the following estimated usable lighting densities:
For ease of maintenance and inventorying bulbs, we set a goal to design the Duplicable City Center to use only 5 different bulb types for all major receptacles through the building. Because the building will have 1000s of bulbs, careful selection of the correct bulb was important and became part of the initial design and evaluation process. This chart/graphic below summarizes the results of our research into this area and why LED bulbs became the clear choice.
Light color was also an important consideration. As color temperature goes higher on the Kelvin scale, it gets whiter and then bluer, and this tends to give a colder outdoor impression. A lower color temperature is yellower and softer, and tends to feel cozy and warm. Here’s an example of the comparison:
Cooler colors are good to use in big wide-open spaces to enhance the airy feeling. Warmer colors are good to use in more intimate places like next to big chairs in the library, in the living quarters, at the dining counter, etc. LEDs come in all colors, as dimmable and non-dimmable bulbs, and also as full-spectrum bulbs with the ability to change them to any color you desire. We chose full-color bulbs for the social centers like the library, Social Dome, and Dining Dome lighting where this variety of colors would be desirable and beneficial. We further maximized the usability of these full-color lights by combining them with dimmable white lights – see the Lighting Tests section for details. We chose dimmable “warm” colored bulbs for all other areas.
We next explored natural light and lighting placement considerations. Bringing in natural light is one of the most effective ways to make a building feel pleasant and comfortable inside while also reducing power needs for lighting. Natural light is also a hallmark of modern architecture, but the more windows you have the more heat can be lost through them and this can increase HVAC needs.
Most of the Duplicable City Center will have a good amount of natural light and natural light dispersement due to the dome shape and big windows placed high up in the domes, but it is also important to complement that with properly placed interior light sources. When interior lights are chosen and placed correctly, the lighting in the room will feel more “natural,” enhance the open feeling of the building rather than distracting, simulates daylight on dark days or in the winter, and they’ll help keep the interior feeling more physically comfortable.
Using a combination of indistinct ambient light and detailed spot lighting is how this is accomplished. This is important because flat even lighting is boring and generally less desirable, like this:
In contrast, what we want to create is more along these lines:
Notice how the second example doesn’t have a ton of natural light but it still feels open and airy. White (or very close to it) walls and ceiling accentuate this even more by reflecting light, an experience we have specifically enhanced in our structure by aiming larger lights up to reflect off these white ceiling and walls to maximize ambient light to mix with the lights from the overhead windows like this:
In areas with a more traditional ceiling (i.e. in bedrooms, bathrooms, and underneath balconies in the domes), a combination of reflective fixtures and in-ceiling can-lights or track lights will be used. A similar feeling of ambient light can be created with fixtures similar to the picture on the right and can-lights create a relatively even amount of light in a room, but still have “hot” spots underneath them that make for a far more interesting visual experience like this:
Having a general idea of how many bulbs would be allowed for each of the domes and the cupola, and having chosen LEDs for our bulb type, the next step was specific lighting calculation and bulb selection. The criteria for number of lights per room was a 50% reduction in
Before placing the various lights in AutoCAD, we tested various configurations using free DIALux lighting software to make sure the lighting plan would supply sufficient and properly distributed light to all areas. This was especially important for the Social and Dining domes because both of these domes have two foundational lighting systems. The first is a floodlight system designed to fully light the room by reflecting light off of the ceiling. The second is a complete system of full-color spectrum lights for making these domes any color we desire. All the lights chosen are LEDs and both systems were designed to provide the minimum amount of light necessary for code compliance and safety.
Here are the Social Dome lighting tests with 38,000-lumen LED spotlights pointed at the ceiling and using the reflected light to light the entire dome. These tests show that just these three lights are sufficient to light the entire room if positioned and aimed properly as shown in Angle Test #3.
Here are the lighting tests using the spotlight positions identified as the best above, and then adding in all the other dimmable and full color-spectrum LED lights that will be mounted on the column and used in the table lamps. Using these alone or in conjunction with the spot lights will allow us to make the lighting in the main room of the social dome any color we desire.
Here are the results of the same tests done for the Dining Dome. The top row of images shows just the spot lights. The middle row shows just the column and table lights. The bottom row shows the combination of both spotlights and table and column lights. As with the Social Dome, the spotlights are dimmable and the table and column lights are dimmable and full color-spectrum LED lights to provide full color-spectrum lighting options for the entire upstairs and downstairs dining areas.
Here are these same lighting tests done for the complete and open source eco-kitchen area. What you see here is a uniform distribution of lights throughout the ceiling with hanging lights to bring more direct light to the work areas.
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One Community’s approach to Highest Good energy is a combination of conservation, functionality, and monitoring, fine tuning, and data sharing. We know people will adopt the solutions we present if we can demonstrate lighting and energy approaches that save people money, still provide functional and aesthetically beautiful environments, and teach people how to replicate them. The Duplicable City Center will do all these things and more while helping us achieve LEED Platinum certification. This page will be where we continue to share all we learn, create, and evolve throughout the process.
None yet… Click here if you have one to ask
Aravind Batra: Electrical Engineer, LEED AP, Principal of P2S Engineering
Dipti Dhondarkar: Electrical Engineer
Erika Yumi Tamashiro: Architecture and Urban Design Student
James Del Monaco: Mechanical Engineer, LEED AP, Sustainability director of P2S Engineering
Joel Newman: Architectural Visualization Designer and owner/operator of Figment
Mike Hogan: Automation Systems Developer and Business Systems Consultant