The Net-Zero Challenge
In the ever-evolving sustainable design and construction arena, many owners and project teams are setting their sights on a goal that seemed improbable just a short time ago: creating commercial buildings that produce as much or more energy as they consume each year, known as net-zero energy buildings.
The Net-Zero Challenge
About DPR's Net-Zero Living Labs
|EUIs||14 kbtu/sf/yr||26 kbtu/sf/yr||23 kbtu/sf/yr||29 kbtu/sf/yr (estimate)|
|Daylighting||Rooftop Solar tube fixtures (Solatubes)|
|Rooftop daylight harvesting light wells|
|Daylight extension strategy – glass walls and reflective surfaces|
|Smart glass – Transitioning tint technology (RavenWindows and View Dynamic Glass)|
|Lighting||High efficiency and LED fixtures|
|Integrated Lighting and Zoning Design|
|Indoor Air Quality||Expanded Occupancy Thermal Comfort Zone|
|Enhanced air circulation - High Volume, Low velocity ceiling fans (Big Ass Fans)|
|Passive ventilation – Large Volume/High Ceilings – Stack Ventilation|
|Evaporative Cooling – Shower Towers|
|Natural Ventilation – Operable Windows and Rooftop Monitors – Solar Chimney|
|Exterior Window Shading/Treatments – Green Screens|
|Indoor Landscaping – In Ground Beds/Living Wall|
|Passive Ventilation – Operable Skylight|
|Heating/cooling radiant sails|
|Dew point-dependent controls|
|Simultaneous energy recovery from hot and cold water loops|
|Dedicated outdoor air system|
|Controls and Building Management||Passive Infra-Red Occupancy Controls|
|Time Controls and Shut-offs|
|Integrated Building Management System|
|Non-Occupied Energy Circuit Shut-off – Phantom Load Management Switch|
|Energy Consumption Awareness/Reduction||Energy End-Use Measurement Submeters|
|Building Energy Use Dashboard Display (Lucid Designs)|
|Occupant Plug Load Management & Measurement System – EnMetric|
|Low-energy and Energy Star equipment|
|Onsite Renewable Energy Generation||Rooftop Photovoltaic (PV) Solar Array|
|Rooftop Solar Water Heating Array|
|Shaded Parking Photovoltaic (PV) Solar Array|
Sustainability Through Reuse
As a company that strives to be environmentally responsible, DPR sees an opportunity to transform buildings seemingly at the end of their lifecycles through reuse and renovation. Each DPR net-zero-energy-certified office uses different techniques to achieve its status, because technology, systems and equipment/products are constantly evolving; some of the technology and products available in 2014 were not available even a few years prior.
Through the four DPR regional offices, as well as the corporate headquarters project for David and Lucile Packard Foundation, DPR recommends the following green strategies when thinking about net-zero projects:
DPR’s LEED Silver Sacramento office was the first privately owned LEED certified building in California’s Central Valley.
DPR’s San Diego office was the first commercial building to achieve both LEED-NC Platinum and net-zero energy status in San Diego.
DPR's LEED-NC Platinum Phoenix office became the largest building in the world to achieve Net-Zero Energy Building certification from the International Living Future Institute's Living Building Challenge.
DPR’s San Francisco office became the first certified net-zero energy commercial building in San Francisco.
DPR opened its net-zero-energy-designed Washington, D.C. office in Reston, Virginia.
The Net-Zero Challenge
Documentation Requirements for Net-Zero Energy Building Certification
Through the ILFI Living Building Challenge program, DPR Phoenix achieved NZEB certification in May 2013, DPR San Francisco in January 2016 and DPR San Diego in May 2016. DPR Washington, D.C., which opened in July 2016, seeks to become the first net-zero energy commercial office space in the Mid-Atlantic region, and will submit for certification after one year of occupying the new office.
The following are the four key criteria for certification:
Sustainable Project Milestones
A Closer Look
Selecting the Right Site to Meet Lofty Sustainable Goals
DPR had maintained a presence in Phoenix’s Camelback corridor since 1998. When it came time to renew its lease, the decision was made to find a new location that would bring the office into greater alignment with DPR’s goals and sustainable mission. Leveraging previous experience, the company decided to pursue a net-zero energy goal for the new Phoenix regional office.
Selecting the site was the first major challenge. The overriding objective was to find an underutilized, existing building in a highly accessible redeveloping area of Phoenix, close to public transportation, that DPR could transform through cost-saving, sustainable strategies to reduce its carbon footprint and benefit the community’s redevelopment efforts. In addition to showcasing the latest in sustainable and energy reduction features, the intention of the project was to demonstrate the value and impact that revitalization has on an urban environment.
The team soon identified a property that may have seemed an unlikely prospect at first glance: an older retail building, seemingly at the end of its lifecycle. Beneath the surface, however, the building’s potential was apparent. Most significant was its location in the heart of Phoenix’s Discovery Triangle redevelopment district, minutes from the airport and in close proximity to a light rail stop that services the downtown core, West Phoenix and nearby cities.
The building’s overall structure was sound and contributed to DPR’s goal to maintain as much of the original structure as possible. Ultimately 93.7% of the original shell and structure remained in place.
The Importance of a Highly Collaborative Team
DPR brought together the entire design and construction team, including architect SmithGroupJJR, sustainability consultant DNV KEMA Energy & Sustainability, mechanical contractor Bel-Aire Mechanical, Inc., DPR project team members, and various consultants and subcontractors, very early on to help identify and select potential sites and then provide input throughout design and construction.
Assembling the right team and then fostering a highly collaborative environment were key to the project’s success. Every team member was hand-selected for the design-build project based on his or her talents and demonstrated expertise delivering high-performance sustainable buildings. Innovation was encouraged, and pushing the limits of conventional approaches expected. The integrated team cultivated a strong sense of trust and was united in working toward a common goal.
The extremely fast-track timeline—10 months from start of design to completion in October of 2011—meant that ideas had to be presented, discussed and decided on immediately. The high-functioning team involved in this transformative project development process ensured that the building’s physical transformation was of the highest quality, and that the end product incorporated the most innovative, sustainable features possible.
During the construction process, sustainability was always at the forefront as well, with 78% of the materials removed from the site ultimately recycled. A goal was to use sustainability strategies that yielded a 10-year return on investment.
Modern Design Fits a Progressive Company
The project’s design reflects the “workplace of the future,” with DPR’s hallmark open office environment instead of traditional private offices.
The building’s modern and innovative aesthetic also takes a “do more with less” approach with sustainability in both building form and function. For example, a green screen with biomass wrapping the facades creates a secure and inviting outdoor courtyard environment for employees while also providing shade for the building.
While the building’s south and west elevations were largely left intact, large expanses of glass were added on the east and north facades to bring in natural light. Horizontal shading devices were used to minimize direct solar gain.
Inside the building, major design features include video conferencing rooms, a learning lab, a fitness room with shower facilities, a modern open kitchen and café area, and roll-up doors that lead to shaded patio areas.
Some of the other unique elements include:
- A “Zen” Room with plush sofa and chair;
- A conical Delta Room that represents DPR’s continuous drive to push the status quo;
- An Innovation Room with sliding glass walls, whiteboard and bold colored reconfigurable furniture designed to inspire creativity; and
- A prominently located 18-ft. wine bar, used as an impromptu gathering space for meetings, celebrations and conversation with clients and staff.
- Inspired geomorphic shapes found in nearby desert canyons are reflected in the building design. A wrapped sculptural enclosure--the Delta room--in the conference space expresses DPR’s self-perform drywall expertise, utilized on this project, while the colors reflect the desert environment just outside. Strategically placed vertical green elements throughout the interior resemble a “landscape of saguaros” while functioning as message boards and power/data towers that break up the open space.
Overall, the project employed a variety of strategies to reduce energy while also creating a healthy environment for employees. A full 100% of spaces can have lights off during daylight hours and 75% have access to exterior views.
Some of the green materials incorporated include:
- 97% of wood from Forest Stewardship Council (FSC) sources
- 32.76% of materials were of recycled content
- Low or no-VOC content for all finishes
- Reuse of DPR’s existing built-in work stations, requiring only 14 additional stations to be built.
Major Sustainable Components to Achieve Net-Zero
At the heart of the project are the many sustainable elements that help the building both conserve energy and produce power needed to offset that demand. Every design consideration impacts the building’s overall performance, and every building component was carefully selected.
A Closer Look
DPR San Diego
Modeling DPR's Net-Zero Energy Journey
For proof of how a net-zero energy building pays dividends over time when measuring both an owner’s return on investment and the building occupants’ satisfaction level, look no further than DPR’s own San Diego regional office building, which achieved NZEB certification in May 2016.
The project team had four primary criteria:
- Bring the outside in; take advantage of the climate and location by opening up the building to the outside.
- Create a net-zero energy office that serves as a model for other commercial building projects.
- Maximize the building’s existing features and only use strategies that yield a 10-year return on investment to serve as a market case for sustainability.
- Represent the company’s core values and respect the individual (in this case, DPR employees).
According to the Environmental Protection Agency’s Energy Star rating system, the new building performs over 97% better than similarly modeled buildings in the area in both use and climate zone. The building’s Energy Use Intensity or EUI (the unit of measurement that describes a building’s energy use) is a low 14, two-thirds lower than Title 24 standards. The mixed-mode HVAC system operates 79% fewer hours compared to a mechanically ventilated building. Water consumption was reduced by nearly half.
Achieving Net-Positive Results
Since its occupancy in 2010, the San Diego office has ended each year “net-positive” as the roof-mounted 64 kW-AC photovoltaic system has generated more than 12,000 kilowatt-hours more than the office consumed annually.
The building is also on track to return all of its premiums related to sustainable construction well ahead of DPR’s 10-year goal.
So how did it achieve those results?
- Capitalizing on climate – DPR’s primary strategy was to capitalize on San Diego’s famous temperate climate to help deliver a majority of the building’s cooling and ventilation requirements. They incorporated a system of motorized operable windows and roof monitors to benefit from prevailing breezes and to help achieve stack ventilation. The operable windows and monitors create the effect of a solar chimney within the structure, providing passive ventilation to the space.
- Solatubes – To reduce dependence on artificial light, DPR enlisted a comprehensive natural daylighting strategy that incorporates 40 Solatubes, south-facing roof monitors, along with energy-efficient lighting fixtures and controls. Water savings are derived from high-efficiency fixtures, low-flow rate metered faucets, and climate controlled irrigation. Natural gas consumption decreased from on-site thermal water heating.
- Open design – Breaking down any barriers to collaboration, the building’s wide-open design and numerous amenities foster interaction and teamwork. There are 11 conference rooms that include the Big Kahuna with La Cantina segmented sliding doors that open to an outdoor patio; the audio-visual loaded training center, capable of hosting a sit-down event for 90 attendees; the circular Delta room; Pipeline, the 16-person video conference room; and Cave Rock, a space devoted to BIM technology, among other things.
- Employee engagement in building performance management – Employees stay informed and engaged in helping facilitate the office’s energy and water consumption with easy viewing of a Building Dashboard featuring data from 12 electrical sub-meters, photovoltaic system, natural gas meter and the indoor water meter.
A Closer Look
DPR San Francisco
After outgrowing its office space in 2014, DPR’s San Francisco regional office moved into an existing two-story 24,000 sq.-ft. structure at 945 Front Street, a block away from the Embarcadero.
The office includes space for 50 DPR employees, 20+ subtenant employees, conference rooms, a central atrium, break area, kitchen and fitness center. With a large training room, and open-concept lobby for holding events, the DPR office is a social space that has been a part of multiple sustainability evenings, conferences, tours and collaborations. The building has incorporated a publicly accessible building dashboard and a LEED dynamic plaque.
Guided by lessons learned from the company’s net-zero energy facilities in Phoenix and San Diego, DPR created its San Francisco office with the following goals:
- Build San Francisco’s first commercial net-zero energy project in the city’s cool and foggy climate.
- Create a high-performance, net-zero energy space on a traditional budget for a Class A+ office space, specifically for under $200/sq. ft.
- Create a living lab of sustainable systems and practices that could be monitored, adjusted and replicated.
- Maximize efficiency and total cost of ownership, by allowing for performance monitoring throughout the lifecycle of the building.
Unique Challenges in the City by the Bay
The San Francisco team was challenged with the task of retrofitting a building to net-positive energy on a budget, within a tight schedule, and in the urban environment of San Francisco. With no space between buildings, the site’s taller neighbors cast shadows over the PV system, which also had to be “right-sized” for San Francisco and its uncertain foggy weather. This was a stark contrast from the consistently warm locations of San Diego and Phoenix.
The project team first set out to achieve net positive energy performance by reducing building loads to a target EUI, which could reasonably be offset by PV on the roof (24 kBtu/ft2·yr [272.6 MJ/m2·yr]). This firm goal was set and agreed upon by all stakeholders early on and enabled the team to find innovative strategies to overcome challenges while upholding the overall project goal. Being surrounded by other buildings on three sides prevented passive design strategies such as natural ventilation and full daylighting from being options.
Competing needs between roof space for photovoltaic panels and skylights, and the need to upgrade the structure to hold the additional weight of insulation and PV panels, were all challenges for achieving net zero energy design at non-premium construction costs. The project ended its first year with a EUI of 20.4 kBtu/ft2·yr (231.7 MJ/m2·yr), significantly lower than the code baseline of 49 kBtu/ft2·yr (556 MJ/m2·yr) determined using energy analysis software and less than the production on the roof of 24 kBtu/ft2·yr (272.6 MJ/m2·yr).
On the Road to Net-Zero
The integrated design build/assist process by which the product was delivered can be considered the project’s most innovative component. Stakeholders were involved in weekly meetings, enabling the use of rapid, collaborative analysis to determine the most cost-effective way to meet the energy target. This complete team allowed the project to move quickly, as demanded by tenant improvement work, and to be cost effective while still meeting the strict net-zero energy goal and incorporating additional costs such as significant structural upgrades.
An integrated design allows for simple, coordinated design solutions that can be easier to operate/troubleshoot than technology-focused building solutions. This concept was part of the design process for DPR from project inception through commissioning. As net-positive buildings have to be monitored and operated continuously for a minimum of a year to be certified, it was important to provide systems that can provide clear feedback and easy monitoring for operators and designers. A building that is hard to control and has complex systems can have an amazing design, yet also result in the building costing more to operate and troubleshoot, potentially offsetting the benefit in energy cost saved. For this reason, the design strategy was to use simple, efficient, off-the-shelf systems such as ceiling fans, tubular daylighting, a whole building “kill switch,” and an increased thermal operative temperature range.
In eight months, DPR, design firm FME Architecture + Design, Oakland-based consulting firm Integral Group and 58 other essential partners, researched, designed, permitted and built a highly-efficient, modern workplace with a number of innovative sustainability features including:
- 343 SunPower 345-watt photovoltaic (PV) panels to produce a 118kW renewable energy system and provide power throughout the office
- Complete structural renovation and roof replacement to support the PV system
- Rooftop solar thermal water heating system
- 19 Solatube750 DS Daylighting Systems
- 8 Velux solar-powered, automated operable skylights over the atrium
- 2 large atrium skylights that were retrofitted with View Dynamic Glazing to control heat gain and diffuse natural light
- 9 8-foot Essence and 4 Haiku® Big Ass® Fans that efficiently promote air flow within the office
- 3 living walls installed by Habitat Horticulture in addition to a living wine bar – live plants growing beneath the glass bar top
- Reclaimed redwood from the deconstructed Moffett Field Hangar One in Mountain View, Calif. and reclaimed Douglas Fir from piles salvaged from the San Francisco Transbay Transit Center Project
- AER-DEC Sink and Ultra-low flow and flush plumbing fixtures by Sloan Valve Company
- Honeywell Command Wall Touch technology incorporated BMS System
- First deployed LEED Dynamic Plaque assisting with tracking building performance
Results: From Electric Bills to Credits
Beyond the cost of design and construction of a building, the long-term effects on total cost of ownership (TCO) are perhaps the most significant outcomes of creating a net-zero energy building. Only 10% of the cost of a building (over its lifetime) is upfront from design and construction, but the building’s operating cost (repairs, maintenance, etc.) is the other 90%.
System Performs Better Than Modeled, Resulting in 20% Net-Positive Energy
- In its first year of occupancy, the San Francisco office used 13% less energy than predicted; design estimates forecast energy consumption at approximately 151,000 kWh, but the building used only 131,000 kWh because of its highly efficient PV panels.
- Due to the PV panels, the office is actually 20% net positive energy at the end of its first year of occupancy. Emissions for the building without PV’s would be about 20 tons of carbon per year. With the PV’s, it is operating at a net positive rate of 5.84 tons/year.
Net-Zero ROI is 30% within 10 Years
- Based on DPR's green project work, the cost premium for building an energy-efficient project ranges from one to 12%, depending on the building type. However, the return on investment for energy efficiency ranges from 5% to 12% within 10 years.
- Although the cost premium for constructing a net-zero energy building ranges from 5% to 19%, the return on investment for net-zero energy is about 30%.
A Bill Becomes a Credit
- DPR received a “bill” from PG&E with a credit of almost $11,000 as a result of the energy that it put back into the grid within a year.
Reduce Carbon Emissions by One-Third Average
- DPR radically reduced its projected total carbon emissions over a 20 year period. The building also reduced its carbon footprint by 37% by the end of 2015. The goal for design energy use intensity, which is energy per sq. ft. per year, was 24 and the actual was 20.3. The average EUI in California is around 60, so the San Francisco office is using only one-third of the average.
Creating a Cost-Effective, Replicable Model
- DPR’s priority was designing a building that is not only sustainable, but also cost-effective and replicable. This project showcased that energy efficient and renewable systems have reached a nearly cost neutral tipping point.
- PV prices have dropped to an average cost of $3.10/watt (installed) in the Bay Area, down from $9-10/watt in 2008. The mechanical cost was $20.70/sq.ft, which is lower than the national average of $23/sq.-ft. for office buildings. Overall, the building cost $160/sq.-ft. and the PV and structural roof upgrades to support the PV cost $40/sq.-ft., slightly higher than other projects in the area, but the estimated energy savings per sq. ft. are predicted to bring down the cost to lower than average in the area. Costs were further offset by taking advantage of incentives and rebates, such as the California Savings by Design program.
A Closer Look
DPR Washington, D.C.
Accessibility was the main driver in moving the Washington, D.C. office from Falls Church to Reston, Virginia. A study on employee locations and commutes, along with the nearby metro line and proximity to the airport made Reston an easy choice. With so much vacant office space in northern Virginia, the team didn’t see a need to build from the ground up. DPR chose to renovate the 20,000-sq.-ft. space, which had previously been vacant for more than seven years, but was close to public transportation, the town center and nearby recreational trails. This decision emphasizes DPR’s commitment to sustainability and to moving the industry forward, showcasing how a Class-C office space with an average skin system can become a net-zero, Class-A office in the Mid-Atlantic climate.
The team set the following goals for its project to be considered a success:
- Create an office of the future that invigorates our people and encourages creative work practices.
- Do the right thing by incorporating sustainable strategies that contribute to the health and wellbeing of the environment and our people.
- Make data-driven decisions based on cost-analysis, payback studies and team member expertise.
- Build a living laboratory where we showcase technologies, products and systems, along with a robust educational program.
DPR's Washington, D.C. office is pushing the envelope when it comes to sustainability. Targeting LEED-CI v4.0 Platinum and designed to be net-zero energy, the space incorporates a variety of sustainable elements, including:
- HVAC – Aiming for net-zero energy, the office first had to reduce their current energy loads as much as possible, using fan-powered terminal units, allowing simultaneous heating and cooling of different areas in the office.
- Radiant sails – In select rooms, DPR Washington, D.C. used Radiant Sails, a system which transforms the centuries-old technology of radiant heating and cooling, into a modern architectural element that is also an extremely energy efficient way to provide thermal comfort to its occupants.
- Natural daylight – the entire 20,000-sq.-ft. area is illuminated by more than 24 SolaTubes that allow a tremendous amount of natural daylight in, while using very little energy for lighting throughout the day.
- Lighting controls – The LED lighting system, combined with a robust control, automation, and sensor system (donated by Watt Stopper) provides a consistent level of lighting throughout the day, while maximizing energy savings. Power outlets also use a phantom load-reducing system that will eliminate all loads from devices not in use after 8 pm.
- Photovoltaic system – A rooftop 147 KW solar array is designed to include 10% more energy than will be required to achieve a net-zero certification through the ILFI program. The Sun Power Helix photovoltaic system will be one of the first of its kind on the East Coast.
- Water efficiency – A highly efficient rooftop solar hot water system provides hot water for all domestic uses, while DPR partnered with Sloan to provide extremely water efficient fixtures in the restrooms and shower facilities.
- Materials – All finished materials in the space (carpet, wallcoverings, tiles, etc.) are certified as Cradle to Cradle. The most notable architectural element throughout the space is the reclaimed wood taken from barns in Connecticut and the eastern shore of Maryland, and installed by our own self-perform carpenters.
- Connection to the outdoors – Adjacent to the kitchen, the office offers access to the outdoors for employees to take a break and get some fresh air, or let the fresh air in. The office has a LED stoplight, programmed to let employees know if the outside weather conditions are acceptable to keep the door open.
Creating a Living Laboratory
As a living laboratory, it was important to the team to be able to educate others, while also continuing to monitor its progress against its environmental goals.
- Lucid Dashboard – A Lucid dashboard provides real-time information related to energy and water consumption, as well as energy produced by the PV array, so the team can visually see what is working and what needs tweaking in pursuit of net-zero energy certification.
- Showcasing Products – New products throughout the space are used as a way to educate clients and design teams on what is possible in an office of this scale. For example, the team installed four different finished concrete options, which allow owners and architects to see what different finished products look like and how they hold up to normal office wear and tear. Other technologies, such as the Radiant Sails, were placed in key, visible spaces so visitors have the opportunity to compare to more traditional systems.
- Mechanical Room – As a technical builder, providing a glass window into the mechanical room will allow DPR Reston an opportunity to educate visitors and its own staff about the functionality of office’s complex MEP systems.
The Path to Net-Zero Continues
As we evolve as a society, so does our built environment. Building net-zero energy offices is now realistically attainable from design, construction, budget and total cost of ownership perspectives. DPR’s four living labs not only showcase the latest sustainable concepts in a variety of regions and climates, but offer the unique opportunity for DPR to study and experiment with what makes the buildings most efficient over time. Leading the way in sustainability and pioneering the net-zero movement, DPR hopes to continue sharing updates and lessons from our net-zero projects to show both industry peers and customers that net-zero construction is a viable option to both save money over time, as well as make a positive impact in this world we all live in.
Updated September 6, 2017