Modeling Suntubes to Design for Daylight

The benefits of natural light within the built environment have now been researched, written about and accepted as a fundamental design characteristic in successful architecture. Creating a connection to the outdoors provides the stimulation required to regulate our circadian rhythms, which can result in improved comfort and productivity. In addition, increasing natural daylight in our homes and work environments decreases the demand for electric lighting and therefore, electricity consumption.

While traditional skylights can provide a good visual connection to the outdoors, suntubes are better insulated, are more efficient at distributing daylight without glare, and don’t have the ‘thermal liability’ of a skylight. Suntubes, Solatubes, SunTunnels, Solar Tubes - whatever brand or label you choose - all are products we often recommend in our projects that have proven to be a real asset to daylighting design. Although they are often located in a project using ballpark guidelines, computer daylight modeling provides more opportunity for strategic placement.  Below are two of our recent projects with examples of how the products were used, lessons learned, and best practices.


Lompoc Transit Center

The Transit Center was built with four large commercial bays that included fleet maintenance spaces, a bus wash station, office space, support and storage space. The client’s experience at other facilities was that the bay doors were being left open to bring daylight into the spaces which caused issues with wind, dust and glare. Rather than closing the doors and installing high bay electric lighting, we were brought onto the team to investigate suntubes as an alternative solution. We ran daylight simulations comparing light levels for different times of the year, with the bay doors open and closed, with different quantities of tubes, and an option of Kalwall systems in certain buildings.

A sample comparison below shows daylight levels on a summer day with eight tubes (left) versus sixteen tubes (right):

Screen Shot 2017-12-11 at 7.59.30 PM.png

The suntubes were very effective in bringing highbay light into a space without using any electricity.

One complication for this project was when we began designing the roof top solar arrays. CalFire requires a 4-foot clearance around all openings, including suntubes, and at the eaves. In our effort to properly daylight the spaces that could not be effectively reached using side lighting, we were also carving out roof top area that would be unavailable for solar modules.

A solution that emerged was moving some of the planned solar PV panels to the canopy over an adjacent work area.  This allowed some of the electricity generation to be assumed by a concentrated installation, while freeing up space on the main building for daylighting mixed with a smaller PV footprint.


Financial Building

This project comprised a three-story multi-use building with significant glazing on all orientations, using a spandrel glazing system. We assisted the design team in improving the building’s daylight by making suggestions such as glazing performance specifications, altering the footprint shape and rearranging interior spaces to increase the depth of daylighting.

Through modeling, we demonstrated that a thinner footprint provided greater opportunity for daylight and had improved energy performance. The architects - Arris Studio Architects - were then able to create a building with great perimeter daylighting. We then focused on improving interior spaces such as common work areas of the third floor. We recommended a “shared light” strategy where suntubes were placed throughout the corridor, and the interior office doors were changed from solid to glazed, creating more consistent light levels on the top floor from the perimeter to the core.

Initially the owner group also wanted a large skylight in the lobby area but after modeling different scenarios, we suggested multiple suntubes that would still provide ample daylight but reduce glare, prevent UV-light from fading the furniture, and reduce heat gain that would have occurred with a single large skylight. You can see in the image below that four suntubes were located in the interior rectangular space directly in front of double doors to bring in light for occupants deep in the space, while single suntubes provide daylight to both the corridor and the adjacent interior spaces (through glazed doors).


Screen Shot 2017-12-11 at 8.06.53 PM.png

Suntubes, interior glazing, a thinner footprint, and coordination with roof-mounted solar panels are all strategies to achieve a high performance building that is a great place to work. To achieve all that, daylight modeling is a great tool for effective design decisions.

Zero Net Energy Series Kicks Off in 2018

Considering a Zero Net Energy (ZNE) project?  Wondering how to get started?  Looking for specific technologies to address your design challenges?

Beginning in January 2018, Zero Net Energy will be the focus of a series of four educational presentations offered the second Tuesday of the month (January through April).  Tackling topics ranging from the newest technologies to tried-and-true practical approaches, the series aims to help designers, contractors and owners understand the foundations of what makes a ZNE building work.

The series is open to the public, registration required.  Cost: $15/$40/$60 (students/members/non-members) for entire series.  To sign up or get more information, see the CCGBC's event website.


Congratulations to CCGBC 2017 Green Award Winners!

The Central Coast Green Building Council's biannual Green Awards were held recently at The Sandbox co-working space in Santa Barbara, CA. 

2017 CCGBC Green Awards logo.jpg

This year's awards were organized in six categories: New Construction, Landscaping, Innovation, Operations, Renovation and Homes. 

In Balance Green Consulting had the pleasure to work on several projects that received recognition.  The 860 on the Wye multi-family veteran's housing project and INhouse: Solar Cal Poly were both honored as Green Homes; the new Caltrans offices in San Luis Obispo were recognized as a  Green Renovation; and MindBody's new corporate headquarters received the top award in New Construction.

Congratulations to all the winners and their project teams!


What's New in 2018: Commercial Clean Energy on the Central Coast

The Central Coast Green Building Council will be hosting an interactive workshop Thursday, November 30, 1-2pm, on upcoming financial incentives for commercial projects considering solar installations.

Attendees will learn about financial products available to commercial property owners as well as hear an update on Community Choice Energy and the Santa Barbara County Commercial PACE (property assessed clean energy) program.

Registration is required.  To learn more, see CCGBC's website for the event.

In Balance Green Consulting Recognized for Excellence in Energy Modeling

The California Multifamily New Homes (CMFNH) Program recently recognized the energy team at In Balance Green Consulting for excellence in energy consulting.  The program is open to new multifamily construction and offers three tiers of cash incentives for energy performance, as well as “kickers” for additional measures such as 100% LED lighting, Energy Star Tier II appliances, high performance walls and fenestration, etc.

CMFH certificate.jpg

Typically we start the process for clients by developing an energy model to be evaluated by the program for eligibility.  By working closely with the Owner, Developer, and CMFNH staff, we can help optimize design choices to meet project and program requirements, and maximize incentives.

This program is funded by California utility customers and administered by PG&E under the auspices of the California Public Utilities Commission.  For more information, see the program’s website.  They are currently accepting applications for 2016 Title 24 Code cycle for projects in PG&E service territory.

If you think your project might benefit from participation in the program, contact us!  We’d be happy to help you get the process started.

Long Beach Celebrates New LEED Silver Library

Last month, the City of Long Beach received the good news that the Michelle Obama Neighborhood Library has earned LEED Silver certification. Replacing the old North Library built in the 1950’s, the new library is a state of the art 24,655 SF single story facility that includes reading and activity areas for children, teens, and adults, as well as three public community meeting spaces.  

In Balance Green Consulting was pleased to join the contractor team, Woodcliff Construction, to ensure compliance with construction phase LEED credits including: regional and recycled materials; low-emitting materials; construction waste diversion; and indoor air quality during and post-construction, among others.

The project took a few unexpected turns that resulted in lessons learned:

1)     Flexibility on design credits: Due to some budget decisions late in the design process, several points in the energy category were lost, jeopardizing a contractual requirement for LEED Silver. Often in publicly-bid projects, the shortfall is shifted to the contractor to make up, so they are left scrambling for expensive specialty materials. It’s a difficult situation, but that was the condition when In Balance and Woodcliff came on board.

After a few all-hands-on-deck discussions, the entire team was tasked with making up points. This team approach worked well since we could evaluate a broad range of design and construction phase credits, based on cost and benefit, to see which were most effective.

2)     Flush-out: Who would have guessed that the flush-out would be scheduled for the three weeks of the year with 90% humidity?! We needed every hour of time available to get the number of hours required. Don’t push the flush-out schedule too close to the grand opening, and be sure to have good data loggers.

Michelle Obama - North Branch - library.jpg

Photo credit: LPA

Congratulations to the project team! 

Architect: LPA

Construction Management: Varin

Contractor: Woodcliff Construction

LEED Construction Consultant: In Balance Green Consulting



Green Building: Acoustic Performance Sounds Good

Within a few years of LEED setting the standard for green building, occupancy surveys were starting to reveal a gap: many occupants were unhappy with the acoustics – noise, noise, noise! Open offices provided great daylight, views, and air movement, but the work environment suffered from inadequate sound isolation. At the same time, carpet and soft goods that can degrade indoor air quality were transitioning to hard surfaces, inadvertently creating echo chambers.

Noise grinch.png

Noise + Echo = Unhappy clients!

Thankfully, LEED v4 has a new Acoustic Performance credit that provides common sense thresholds for typical building spaces, whether or not a project is pursuing LEED certification. Here’s a quick rundown of the credit’s four criteria and how it might apply to your project, whether new or existing:

1)     Sound Isolation: Isolation for walls, floors and ceilings is measured by Sound Transmission Class (STC), with higher STC rating required between sensitive uses. Isolation between offices should be STC 45, Classrooms require STC 50, and if you have an equipment room, you’ll need STC 60 to keep the noise down. Make sure isolation includes the ceiling, interior glazing and doors.  Here are typical STC Ratings:

Screen Shot 2017-10-27 at 3.15.11 PM.png

Keep in mind that these STC ratings assume no sound flanking, i.e. sound that travels through unsealed walls, ungasketed electrical outlet boxes and recessed lighting, and dropped ceilings.

2)     Reverberation Time: This can be complicated science but the LEED credit provides reasonable criteria for common uses so you have the right balance of sound absorption and reflection. For concert venues and some restaurants, you want spaces to be ‘live’ in strategic locations – leave this to your professional acoustic consultants! – but mostly the goal is to have speech be clear and understandable.  A classroom building for the Air Force Reserve was designed with acoustic ceilings, but calculations showed that the reverberation times were still too long, so a few acoustic panels were added to the walls.

3)     HVAC Background Noise: This element follows ASHRAE standards, depending on use, but it does need early evaluation. For a recent hotel project, the owner was considering PTAC units, commonly seen at the exterior wall in guest rooms. No reasonable isolation can bring down the noise for these units, so a more acoustics-friendly choice would be heat pumps or other traditional system where the HVAC equipment is more remote, with appropriate isolation springs or other treatment.

4)     Sound Reinforcement and Masking: Finally, there are requirements to evaluate the need for and performance of sound reinforcement/amplification for any space accommodating 50 people or more.

Ideally, your project includes an acoustic consultant on the team. If not, or even just as a head start, using LEED Acoustic Performance criteria to evaluate sound isolation, reverberation time, background noise and sound reinforcement could trigger adjustments that will help create a more healthy, productive indoor environment and happy occupants.