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Net Zero Roundtable

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net zero roundtable metal architecture june 2014 ralph dinola new buildings institute

Ralph DiNola, executive director, New Buildings Institute, Vancouver, Wash.

net zero roundtable metal architecture june 2014 david stermer metal sales manufacturing

David Stermer, director of engineering at Metal Sales Manufacturing Corp., Louisville, Ky.

net zero roundtable metal architecture june 2014 greg mella smithgroupjjr

Greg Mella, FAIA, LEED AP BD+C, vice president, co-director of sustainability at SmithGroupJJR, Washington, D.C.

net zero roundtable metal architecture june2014 brian court the miller hull partnership

Brian Court, AIA, LEED AP, principal, The Miller Hull Partnership LLP, Seattle

net zero roundtable metal architecture june 2014 justin harkins thermal design

Justin Harkins, vice president, sales at Thermal Design, Stoughton, Wis.

The push for net zero energy buildings has increased in recent years, with the New Buildings Institute reporting that the number of verified net zero energy buildings or those targeting net zero energy has more than doubled in just two years, from 60 in 2012 to 160 in 2013.

The International Living Future Institute, creator of the Living Building Challenge, even offers the Net Zero Energy Building Certification, designed to verify the buildings that rely on energy conservation and on-site renewables to achieve all of its heating, cooling and energy needs.

Since net zero energy is something that we will continue to hear more about, Metal Architecture took this opportunity to speak to some people in the architecture and construction industries to learn more about their thoughts on net zero energy buildings.

1. What are the most recent trends in net zero building design?

Ralph DiNola: The current definition of net zero energy buildings is generally understood as those that consume only as much energy as can be produced on-site through renewable resources. Since space for renewable is typically limited and the cost is relatively higher than energy efficiency measures, the first step in achieving net zero energy performance is to design an ultra-low energy building.

New Buildings Institute (NBI) research shows that most net zero energy buildings have an Energy Use Intensity (EUI) under 40 kBtu/SF/year, with a national average around 20 kBtu/SF/year. The second step to achieving net zero energy performance is to add renewable energy systems. Most common are photovoltaics (PVs), but multifamily projects often include solar thermal for domestic hot water.

Integrated design is the most critical aspect of creating a net zero energy building. In this process, the owner, architect, engineer and other critical roles on the design team, work in concert to ensure that the interrelationships between the building and its systems, surroundings and occupants make efficient and effective use of all resources.

Under an integrated design process, key efficiency considerations include optimizing the building envelope for thermal efficiency, occupant comfort, daylighting and natural ventilation. Advanced lighting strategies that include high efficiency equipment coupled with controls and right-sized, high efficiency HVAC systems are other measures that design teams give special attention.

Beyond the design owners and operators need to manage plug-and-process loads, work to understand the most efficient option for each component, and drive down those loads. Building occupants should be educated about the energy efficiency features of the building and engaged in what actions they can take to keep energy use in line.

David Stermer: Recent trends include high-efficiency HVAC and lighting, along with seasonal thermal energy storage. Additionally, the interest in Passive House, which features a low air permeability of the exterior envelope, is increasing.

Greg Mella: One trend is envelope commissioning, which provides a means of ensuring that the robust building enclosures we design-as a necessary component to extreme energy conservation-get built and tested. We are also seeing more performance modeling and simulation during the design process, especially early on. To achieve net zero, performance modeling is critical to optimize the performance of orientation, window design, daylighting, exterior sunshading, envelope and so on. Another trend is with energy metering information, as it's being integrated into everything from light switches, to power strips, to systems furniture. Monitoring behavior has a huge role in energy consumption. Making the energy implications of the way we use a building evident to the actual users really drives home conservation. It even stimulates a little healthy competition!

Brian Court: Active exterior solar controls are very effective tools building designers can utilize to minimize solar heat gain, control glare and direct light deeper into occupied spaces. All of these strategies help minimize energy loads making them a vital first step toward successful net zero design. While these systems are prevalent in Europe, they are just starting to make inroads in the U.S. market. We will be seeing more and more of this technology.

Justin Harkins: Recent cost reductions and quality improvements in LED lighting are a trend that is having a significant impact on the economics of net zero building designs. Lighting energy consumption is generally second only to HVAC consumption in buildings. In the past, the challenge of adopting LED lighting often involved making sacrifices in some combination of cost, color quality, light output and directionality that could render them impractical for many applications. Now, there are an increasing variety of LED lighting options that perform very well in all of those specifications. While the lighting efficacy is not always an improvement on florescent lighting, the life cycle cost is reduced by long life of the LED lamps.

2. What are some design considerations with metal to keep in mind when designing net zero energy buildings? 

Harkins: Metal buildings can be a surprisingly economical structure for net zero projects when you have an understanding of the obstacles and how to work around them. Unfortunately, the conventional methods of constructing metal buildings with ineffective thermal envelope due to compressed insulation, excessive thermal bridging due to exposed secondary structure, and high infiltration are a poor starting point.

Upgrades to R-values have little impact if those additional R-values are reduced by even more extreme compression or if the purlins and girts are not thermally isolated. Lack of thermal performance of conventional metal building envelopes require corresponding increases in heating and cooling equipment capacity that result in avoidable up-front and and ongoing costs for the owner.

Insulating the building properly is the key to economically reducing the energy consumption of metal buildings. This is because the investment in insulation is either entirely or substantially offset by other project savings, including reductions in HVAC equipment costs. On a typical project, this can make the payback timeframe on this investment as low as zero, which has an enormous impact on the economics of designing to net zero.

While the costs of solar PV modules have come down drastically in recent years, it is still more economic to invest in reducing energy consumption first. Through a comprehensive consideration of the insulation, HVAC, lighting, controls, internal loads, cost trade offs and an operational plan, consumption can be reduced such that the cost of the necessary renewable power generation equipment becomes manageable, not just for big budget projects, but for every day projects as well.

Stermer: There are several design considerations architects should keep in mind, including:

  • Color-solar reflectance.New color technologies are available that provide a high Solar Reflectance Index (SRI). These colors reflect solar energy that is usually absorbed as heat. The result is a cooler roof and less energy needed for cooling needs.
  • Roof slope and orientation, which affects the amount of solar energy on the roof. If solar panels are being utilized, then the roof orientation and slope should be considered. It's important to design the roof to receive the highest amount of sunlight to convert to usable energy. If the roof has the wrong slope or directional orientation, there is risk that the solar panels will not have enough exposure to sunlight to create enough usable energy for a net zero building.
  • Attachment of local energy production equipment. For net zero buildings, it is crucial to choose an appropriate panel profile. If a traditional solar panel is used, a ribbed panel is ideal because the attachment hardware can be clamped to the panel ribs, therefore eliminating the need to penetrate the panel. If a thin film solar panel is being used, then a flat-pan panel is ideal because the panel should be adhered to a surface that's as flat as possible. Striations can prevent a strong adhesion.
  • Metal panels are ideal for solar attachment. The panels do not require penetrations for attachment, and the life span of metal roofs are far beyond that of solar panels.

metal architecture net zero roundtable bullit center seattle miller hull partnership metal sales manufacturingDiNola: Metal materials have a lot to offer net zero energy buildings. Standing seam metal roofs provide an ideal roof surface for PV system installation and metal siding provides a durable siding material and effective rain screen for long lasting high performance buildings. Exterior metal shading devices can provide effective glare control as part of daylighting strategies.

Court: The finish and color of metal siding can be a useful tool to either reflect or absorb the sun's energy. Design teams should consider the potential of both.

Recent advances in coating and finishes have shown the potential to mitigate air pollution through the application of a titanium dioxide coating. This was first introduced to the building industry by Alcoa [Architectural Products, Eastman, Ga.] on their Reynobond aluminum panel product. Not only are the panels self-cleaning, but they will actually pull pollutants out of the air near the panels, break down into organic matter, which is then washed away with rainfall. This type of groundbreaking coating has exciting potential as buildings look beyond simply net zero toward regenerative design.

Mella: Metal exterior cladding systems and framing is often used in sustainable design because metal can be extremely durable, but metal also conducts thermal energy. Designers need to be extremely mindful of thermal bridging to make sure the super tight, highly insulated skins we create do not have major leaks from thermal bridging. Thermally broken connection details and strategies to ensure continuous insulation at the building envelope become paramount.

3. What has the demand been for net zero buildings?

Court: While it's difficult to quantify the demand, one thing that is certain is that the demand is increasing. Where 10 years ago there were none, at least a half dozen net zero buildings have now been built or are on the boards.

Stermer: The demand for net zero buildings seems to be increasing at a moderate rate, although there seems to be the highest demand in Europe. Last year Metal Sales executed several successful net zero projects and see opportunity for more in the future.

Mella: We're finding that more and more clients are interested in net zero. Maybe three years ago, clients were interested but did not think achieving net zero would even be possible. Early innovators have demonstrated net zero buildings are possible and a variety of scales, climates and program types. We are even nearing the threshold where a net zero energy building will be commercially viable in many parts of the country.

Harkins: The interest in net zero is certainly increasing, but there is much more room for growth. Many people still assume that net zero projects are only for big budget projects and owners who have a high tolerance for payback. With a comprehensive design approach that takes advantage of the synergies of this type of design in a metal building, net zero can be a great investment on a broad range of building projects.

DiNola: This trend is still nascent, but poised to move quickly. In 2012, NBI identified 21 net zero energy buildings in North America that we were able to verify by reviewing energy use data. We found an additional 39 buildings that were energy efficient enough to be net zero energy, but did not take the step of adding renewable resources on-site. Finally, another 39 buildings were identified as working to achieve net zero energy performance, but were either still under construction or did not have a full year of energy use data.

In 2014, the number of net zero energy-verified projects grew to 33 including 32 buildings and one district-a set of buildings achieving net zero energy. The number of ultra-efficient buildings with energy performance on par with net zero energy, but without the on-site renewables grew to 53 and the number of commercial buildings working to achieve net zero energy rose to 127.

If all the buildings identified in 2014 achieve net zero energy-level performance in the next two years, we will have more than doubled the number of buildings in just four years. This kind of growth mirrors our experience with green building and LEED. Initially, the numbers were small, but then grew exponentially to transform the building design and construction marketplace in favor of sustainability.

4. Are there areas of the country where the desire for net zero has been more prevalent?

Harkins: The interest in net zero projects is from coast to coast and in between.

Court: The greatest interest is in the Pacific Northwest but examples can be found across the country and globally.

Mella: Yes. The Sun Belt is still the most prevalent location for net zero buildings. Our headquarters for DPR Construction in Phoenix, and our Energy Systems Integration Facility for the National Renewable Energy Lab (NREL) in Golden, Colo., are good examples. The financial viability of photovoltaics as the on-site renewable energy source in these regions with excellent solar availability makes net zero pursuits more achievable. But net zero projects are springing up in the least likely of places like Seattle, a city with limited solar availability. We have our Brock Environmental Center project under construction in Virginia Beach, Va., which is a hot and humid climate that puts a priority on energy-intensive cooling.

Stermer: There seems to be higher interest levels in high population areas, such as the Northeast, West Coast and Texas. However, with the recent federal mandate for building to new or net zero energy standards, the desire is more uniform across the country.

DiNola: California leads with 10 net zero energy-verified buildings and significantly more under development because of the Governor's leadership and policymaking in this area. But other states are poised to follow as net zero energy policies and practices are increasing seen as an effective means to create resilient buildings and curb greenhouse gas emissions.

net zero roundtable metal architecture june 2014 university of california davis west village 5. Who do you find is requesting net zero buildings? Is there more interest in the public versus private sector?

DiNola: Currently, the public sector leads in pursuit of net zero energy performance in buildings. This kind of trend is very similar to what we saw in the green building movement. As public projects demonstrate feasibility and model the potential for net zero energy design and construction practices, private sector will follow suit.

In 2014, NBI found that of the 160 buildings that were either verified net zero energy or targeting net zero energy performance; 26 percent were owned by private companies.

Stermer: There seems to be more interest in the public sector due to the Executive Order that 15 percent of existing federal buildings conform to new energy standards by 2015 and that 100 percent of federal buildings be net zero by 2030.

Harkins: The demand we have seen is more often for public projects, though there is private interest as well. I think this goes back to the perception that longer payback timeframes are required. Public entities generally have a longer time horizon, and tend to explore their options. Private owners may not consider it based on that perception, or if they do, there are many builders who don't understand how to do net zero economically, because the approach is so different from conventional metal buildings. When we have an inquiry about net zero from architects, owners or contractors, we first try to address those misconceptions first by walking them through our EnergyCraft Design process for rebalancing the building design, and then provide energy analysis of various design options to help them make informed decisions about the energy performance of their building.

Court: There is almost an even split between single-family residential, commercial and institutional. Single-family clients tend to be motivated by their own moral compass and simply want to do the right thing. Commercial projects are either concerned with being perceived by their peers as innovative or could be mission-driven to demonstrate environmental concern. Institutional clients, who plan on owning and maintaining their buildings for the life of the building have often been motivated by life cycle cost analysis and understand that while net zero buildings will have a higher initial construction cost, that investment will pay dividends in the long run.

Mella: We've seen a real variety of private, public and nonprofit clients requesting net zero. Our net zero design for DPR Construction is a good example of a private client, motivated by a sense of stewardship. Our design for the Energy Systems Integration Facility at NREL is a good example of a public client wanting to embrace federal mandates that seek net zero. Finally, Chesapeake Bay Foundation's Brock Environmental Center is a good example of a nonprofit client wanting to walk the talk and encourage others to follow their leadership.

6. Do you think there will be more net zero residential communities popping up across the nation? Why?

Stermer: Yes, because of energy codes and a continued push to reduce environmental impact in architectural design. At Metal Sales, we've noticed an increase in net zero communities, multi-family housing and residences. We expect this trend to continue with the growing push toward net zero.

Court: Yes, we see greater potential in the private market where individuals can more easily prioritize and make the upfront investment though, as described earlier, life cycle cost analysis should make net zero buildings more attractive to any entity that plans on occupying a building for a term longer than that of the construction loan.

DiNola: Absolutely. Evidence in California and other parts of the North America show that net zero energy residential communities are technically feasible and cost effective today. The state of California has a goal for all new residential development to be net zero energy by 2020 and other states and cities such as Vermont, Rhode Island, Salt Lake City, and Washington, D.C., are looking at policies that will drive zero net energy projects in their jurisdictions.

As feasibility expands for more buildings types and larger square footage, net zero energy offers a critical solution for addressing carbon mitigation mandates and higher resiliency in buildings. Buildings account for about 40 percent of the carbon emissions in the United States, but in some cities that number approaches 80 percent. Policymakers understand that dramatically improved efficiency for buildings will be required if we are going to tackle the challenges presented by climate change.

Net zero energy buildings are good business as well. Developers such as Gary Christensen of Boise, Idaho, are finding a positive return on investment for the value of net zero energy buildings.

Harkins: There is already great interest from a segment of the population in net zero homes, and energy conservation. The technology advancements and economies of scale of home automation products have increased the tools available to homeowners to help reduce energy savings at home. Also, with individual families the decision to reduce energy consumption is not always primarily driven by economics alone, but can also about social consciousness or just enjoying technology as a hobby. I myself installed all LED lighting, photovoltaics and Energy Star appliances in my home over the past two years. As a result, my net electricity consumption at my home for the last four months was only 26 kWh!

A positive aspect of this interest by homeowners is that some of the consumer off the shelf technologies developed for that market can be adopted for commercial metal building projects as well.

7. What do you think is the future of net zero?

Court: Net zero buildings will continue to become more wide spread and we are seeing interest in buildings that are not only net zero energy but also net zero waste, water and toxin free, most notable are buildings certified by the Living Building Challenge.

Stermer: Products that help achieve net zero, including efficient lighting, HVAC and heat energy reclamation will continue to mature. Strategies, such as reduced energy use, energy production and energy reclamation will also mature over time. Additionally, on-site/local energy storage, or the reliance on the grid during times of peak usage, is not necessarily reduced by current net zero measures.

Harkins: The potential benefits of local and distributed renewable power generation, including the impact on our environment, energy infrastructure, dependence on foreign energy sources, and our economy are tremendous. However, for net zero buildings to become the norm for new construction, the economics need to be there. Metal buildings have some unique advantages in delivering economic energy performance, and this will be a great asset to the industry in the coming years.

Mella: The 2030 Challenge set the building industry on a path to achieve net zero energy for every building we design, by the year 2030. When these targets were established in 2005, 2030 seemed like a long way away. We are now a decade closer to that target date, and I've been extremely encouraged to see early adopters and pioneers provide examples that net zero energy buildings are possible. It gives me optimism that the aggressive goal established in the 2030 Challenge can be met by the mainstream following the path of these early examples. As the efficiency of photovoltaic panels goes up while at the same time the costs for PVs come down and simultaneously the cost for non-renewable purchased energy goes up … well, we are nearing that tipping point. And when the economy reaches that tipping point, the building industry will have the knowledge to make a net zero energy future a reality.

DiNola: NBI research shows that net zero energy buildings are technically feasible and are already happening in 36 out of 50 states, across a broad range of building types and sizes with strategies and technologies that are readily available. Developers in California and other states are developing speculative net zero energy buildings. I believe that this emerging trend will become mainstream in the next decade. A growing network of owners, developers, practitioners, contractors and suppliers are aligning their efforts behind this next wave of sustainable development. Like LEED, this market transforming movement is poised to dramatic change practices in the building industry.