Christina Aßmann Presents at Greenbuild International Conference on Nuthatch Hollow

Christina Aßmann, Project Architect at Ashley McGraw Architects, presented at the 2018 Greenbuild Conference and Expo in Chicago, IL on Friday, November 16, 2018. Along with Amber Bartosh, Assistant Professor at Syracuse University School of Architecture, they presented “Virtual Reality: An Emerging Tool for Sustainable Design.”

The presentation will highlighted the application of VR as a visualization and simulation tool to support the design process and educational outreach of Nuthatch Hollow. The presentation demonstrated how an immersive VR representation of the project that included environmental analysis and interactive educational content supported the understanding of the sustainable quality of the built environment. It introduced critical aspects of the Living Building Challenge criteria and how the Nuthatch Hollow Project design team met them using passive house standards to help reduce energy emissions. These design aspects and more are highlighted through a VR walk-through that easily conveys to the client and public how these design decisions contribute to a better built environment. The presentation explained the workflow for incorporating energy data in the immersive 3D environment. The presentation ended with a hands-on demonstration of the Nuthatch Hollow VR environment and invite participants to engage directly with the project.

Greenbuild is the world’s largest conference and expo dedicated to green building. Sustainability is the foundation of Greenbuild. The theme for Greenbuild 2018 is Human By Nature (styled as Human x Nature). The green building movement embraces all of humanity by making sustainable buildings and environments accessible to everyone, and in doing so, benefits the natural environment all around us.

Greetings from Portland – Living Future unConference

This week, Pamela Mischen from Binghamton University and Matthew Broderick and Susanne Angarano from Ashley McGraw will be discussing Nuthatch Hollow at the Living Future unConference in Portland, Oregon. The Living Building Challenge has great power to transform thinking. Meaningfully involving more people in the design process deepens the impact. For Nuthatch Hollow students, faculty, staff, and the broader community play significant roles. Our presentation at the International Living Future unConference will explore the concept of Radical Collaboration. How can we engage more people more deeply into the design processes for deeply sustainable facilities, thereby magnifying their impact? This highly interactive workshop will engage the entire audience in thinking about employing Radical Collaboration on their own projects.

The Presentation
The Living Building Challenge has great power to transform thinking. Meaningfully involving more people in the design process deepens the impact. For Nuthatch Hollow, a Living Building in design at Binghamton University, students and faculty play significant roles, including taking primary responsibility for materials research. Through classroom curriculum and associated internships, students received extensive training on materials research then broke into teams under the direction of a student “CEO” to research materials. This involves contacting hundreds of manufacturers, reviewing extensive chemical ingredient lists, searching for alternatives, and advocating for change in manufacturing processes.

The Conference
ILFI’s focus this year on Authenticity in Action will allow the green community to bring our unique backgrounds, experiences, and personalities together to instigate united and thoughtful movement toward a living future. Celebrate 12 years of innovation and partake in out-of-the-ordinary sessions, listen to inspiring keynote speakers, and join the movement that starts at the unConference.

The Institute
International Living Future Institute is an environmental NGO committed to catalyzing the transformation toward communities that are socially just, culturally rich and ecologically restorative. Composed of leading green building experts and thought-leaders, the Institute is premised on the belief that providing a compelling vision for the future is a fundamental requirement for reconciling humanity’s relationship with the natural world.

Biophilic Design


The design team is embracing the principals of Biophilia to help guide the design decision making as well as work towards compliance with the Living Building Challenge Imperative 09: Biophilic Environment. As defined by ILFI, biophilia is “the innate, genetically determined affiliation of human beings to nature and other living organisms”. Manifestations of this could take many different forms, from biomimicry, to sensory variability, to using organic shapes. These and other strategies are categorized under environmental features, natural shapes and forms, natural patterns and processes, light and space, place-based relationships, and evolved human-nature relationships.

The kickoff to this design thinking for the Nuthatch Hollow project was the Regenerative Development Workshop, facilitated in October of 2016. The workshop brought together the design team, Binghamton University students and faculty, and the wider community, on site, to immerse themselves in the essence of Nuthatch Hollow. After exploring the nature preserve, learning more about its history, and connecting with others, the workshop group produced a list of words that spoke to them about what the spirit and essence of Nuthatch Hollow are and the elements that make it so unique. The awe of nature, and human’s affinity for it, are most definitely invigorated in this beautiful place. The goal to incorporate the natural elements of Nuthatch Hollow within the building is unanimous and the list of words have been a constant driver through the design process.


The Essence of Nuthatch Hollow:

  • diversity/variety (habitat, topography…)
  • movement
  • rhythm
  • discovery
  • balance
  • resilience
  • ancient
  • complex
  • rejuvenating
  • happiness
  • oasis/sanctuary
  • water
  • nutrients
  • changing/evolving
  • energy
  • understanding
  • layered
  • intertwined
  • sensory (sight, sounds, smell, touch, taste) >all 5
  • random
  • connection separateness
  • mystery


The essence of place together with the contextual knowledge and site research are leading the development of the following biophilic design strategies in the building design:

  • Locating the building along the seam of a hill so that visitors approach the building from above, descending to the entrance, cultivating curiosity and inviting exploration, acting as a gateway into the sanctuary.
  • Orienting the building to not only for solar considerations but for optimal views of the pond to the South, bench to the North, and clearing to the West.
  • Using wood species and stone types local to the area and found within the nature preserve to provide a strong contextual relationship between the building and its surroundings.
  • Designing the interior in a simple manner with framed views to the outside to provide a neutral background for the beauty beyond.
  • Purposeful placement of windows to provide dynamic multi-direction daylighting within the building, providing an effect more similar to being outside.
  • Coordinating ceiling elements with window placement to create shadows mimicking sunlight filtering through the trees in the forest outside.

As the detailing of the design and the material vetting continue, these strategies and the principles of Biophilia make the design even more grounded in place, aligned with the spirit of Nuthatch, and true to the goals of the project.

Written by Susanne Angarano, Principal/Senior Interior Designer, Ashley McGraw Architects

Composting Toilets and Passive House

LBC requires net-zero water, meaning the water that falls on the defined LBC project site in a year determines the project’s allowable water use per year[1]. Composting toilets are a commonly used strategy to achieve this level of water use reduction. The composting process allows water to be saved from use as a carriage medium. The project plans on using foam flush composting toilets by Clivus Multrum with a composter beneath which requires continuous ventilation. Exposure to constant air flow is necessary to allow the mixture of toilet waste and bulking material to convert to usable compost and liquid fertilizer. The continuously operating composter fan creates negative pressure at the toilet fixtures for odor control. The challenge is how to deal with this specialized system while meeting the heating goals set by PHIUS – direct exhaust would result in an insurmountable energy penalty. Two approaches are being investigated:

Keeping the composter ventilation separate from the main ERV:
This would involve a secondary ERV unit to serve the composting toilets only.

Integrating the composting toilets’ exhaust into the overall ventilation system:
This requires the use of an ERV that has virtually no cross flow leakage. This will prevent the exhaust from entering the supply air.


Conclusion to the Passive House Series of Posts:
To create a regenerative and resilient world where humans live in alignment and contribute to the natural systems we are part of, the best strategies and thinking need to be combined, synthesized and deployed. Combining Passive House and Living Building Challenge forced the project team to think and rethink goals, processes and outcomes in a way that maximized benefit and created abundance. For example using Passive House standards to achieve a net positive energy building that meets the Living Building Challenge the design team is creating a building that uses less energy than allowed by LBC and at the same time eliminates the need to use the fossil fuel allowed by Passive House. Finding components and materials that can achieve the rigorous thermal and airtightness requirements of Passive House as well as satisfy the toxicity reduction goals of LBC makes for a better building and a healthier planet. Combining the deep and thoughtful work embodied in Passive House and Living Building Challenge is a wonderful struggle that is leading the team to be innovative, creative and regenerative.

[1] Living Building Challenge 3.0 Water Petal Handbook

Written by Christina Aßmann and Nicole Schuster, Ashley McGraw Architects

Energy and Passive House

The Passive House Source Energy target equates to site energy usage multiplied by a utilization factor of 3.16 for US electricity; for a non-residential building this target is 38 kBTU/sf/yr. For a 2500 sf building, this translates to 8,782 kWh/yr in site energy (building energy) use. The relatively high occupant load for this project, combined with the restriction on combustion, makes this a difficult target to achieve.

LBC requires net-positive energy, but allows achievement of this target with unlimited renewables, whereas Passive House limits the amount of photovoltaics (PV) which is “deductible” from the project’s building energy use to reach the target. Incorporating battery backup energy storage increases the amount a project can deduct for PV.

This project has undergone a feasibility study by the Passive House Institute US. The design team provided design drawings, a 3-D model, design and mechanical narratives, occupant schedules and usages to the staff at PHIUS. PHIUS then used that information to create a WUFI energy model for the project, which contained two design cases – one as proposed by the design team, and a second modified as required to meet Passive House requirements. The model verified for the design team that the source energy target was the most challenging aspect of Passive House for this particular project, but that the target was achievable through incorporation of an 8kW PV array and minor modifications to envelope components and mechanical system efficiencies. The PV necessary to achieve the LBC Net-Positive Energy target is greater than the 8kW array needed for Passive House, so the project benefits from the combination of the two standards, in that the LBC Energy Petal also helps the project achieve Passive House.

For this project to achieve Passive House, based on the Passive House Case in the WUFI model provided by PHIUS, the ERV efficiency level needs to be 85%, and the envelope design needs to provide insulation levels of R-83 in the roof, R-61 in the above grade walls, R-50 in the below grade walls, and R-48 in the slab, with U .12 windows. The model is extremely useful as a tool to analyze trade- offs and decisions. For example, lowering the efficiency of the ERV results in a failure to meet the heating load limit, which would result in a need to increase insulation levels to compensate. As the insulation levels described are already high, which equates to thick envelope components, it would be preferable to find an 85% efficient ERV which meets the other LBC requirements. In another case, reducing the coefficient of performance (COP) of the heat pump results in a failure to meet the source energy target with the 10kW PV array as modeled; however, since the designed PV array is larger, the project may be able to absorb a slight reduction in heat pump efficiency. At the same time LBC does not allow a gas-fired water heater, and an electric water heater results in a failure of the source energy target. The PV could potentially cover the electric water heater energy use, depending on other trade-offs taken, otherwise a combination heat pump/water heater would need to be incorporated. As a goal of the project is to minimize the energy use to reduce the amount of PV required, the design team will need to make these choices carefully.

Our next post will briefly discuss the considerations for including composting toilets in a Passive House design, and provide a conclusion to our Passive House series.

Written by Christina Aßmann and Nicole Schuster, Ashley McGraw Architects

Why Passive House?

As an enhancement, and complement, to the Living Building Challenge; the design team is working to meet the Passive House Standard for Nuthatch Hollow. The Living Building Challenge is rigorous, demanding, and well-rounded as a “Sustainable Building” standard. It sets up a great framework for nesting smaller scale, more specific goals.

The LBC Energy Petal intent is “To rely solely on renewable forms of energy and operate year-round in a safe, pollution-free manner.” [i] To satisfy this intent, petal achievement requires the project to supply 105% of its energy needs by on-site renewables on a net-annual basis, without on-site combustion, and provide energy storage backup for resiliency. A project meeting this requirement is creating more energy than it uses every year. As net-zero buildings become more mainstream, the LBC net-positive energy target is the next step forward to doing good, rather than less harm.

As a complement to the LBC requirement, the intensive energy use reduction requirements of Passive House result in an even better investment: a building with a greater level of resiliency than that of net positive energy alone. The Passive House Standard lends further rigor to the energy design of the project, resulting in a building which remains comfortable and safe in changing climates and extreme weather, with less reliance on energy production systems. The building science based approach of Passive House results in durable assemblies and healthier buildings. The combination of these two standards surpasses the achievements of each of them on its own.

One of the goals of this project is to serve as an example, and a teaching tool, for how to design better, more sustainable buildings, to make sustainable design and construction more accessible to everyone. Passive House is based on the concept of global energy sharing, in that everyone on the planet gets the same energy allowance, sized to mitigate climate change. In order for this to work, it needs to happen on a global scale, which means it needs to be achievable by everyone. The more Passive House (and LBC) projects which are constructed, the more mainstream these targets and strategies will become. Through this process and this project, people will learn about Passive House and the ways they can apply the same strategies, goals and principles to their own houses and buildings.

How these two standards work together is a significant area of exploration at this stage of the design process. Over the next couple blog posts we will discuss specific aspects of that exploration.

Written by Christina Aßmann and Nicole Schuster, Ashley McGraw Architects


[i] Living Building Challenge 3.0 Energy Petal Handbook

Design Development Update

The design team is now approximately halfway through the Design Development phase. As such we are continuing to develop many aspects of the building. In this post we are sharing three recent renderings of the exterior and interior to highlight the progress.

For the exterior we are continuing to refine the design. The roof slope over the multipurpose space has changed from a v-shaped roof to a continuous slope. This simplifies the building envelop, makes detailing and ventilation of the roof more effective, and provides more area for photovoltaic panels. We are hoping to fit all the required PV panels onto this roof surface. The exterior is still predominately clad in wood and stone, though the details have developed somewhat since the end of Schematic Design. We have continued to refine our daylighting strategies which are reflected in the current arrangement of windows, sun shades, and roof overhangs.


We are just beginning to refine the design of the interior spaces. The rendering shows the interior of the multipurpose space. The team is working to incorporate principles of biophilia into the design and incorporate some of the essences of Nuthatch that were articulated at the regenerative design workshop last year. We are also fine-tuning our approach to daylighting and acoustics. In a future post we will do a walkthrough of the interior design elements and explain the concepts and approaches.

In addition to creating a Living Building, the team is working to incorporate Passive House design principals into the building. This will be a great help in reaching Net-Positive Energy. Our next post(s) will explore this aspect of Nuthatch further.


Nuthatch Next Steps – Design Development

Schematic Design has wrapped up, and classes are coming to their hectic close. We now look forward to the start of “summer” while we enjoy all that spring in Upstate New York has to offer. The Nuthatch team, designers, faculty and students now dive headlong into the next phase of the project, Design Development. This is where all those ideas developed during the concept and schematic phases get turned into reality, something that is buildable and meets Living Building Challenge (LBC) requirements. Some key areas of focus in the near term include the following:

  • Further developing the building itself, especially details of the wall and roof assemblies. These assemblies need to be highly insulated, requiring careful consideration of building science and constructability.
  • Development of the mechanical and power systems. Between this and the detailed design of the wall and roof assemblies we will be aiming to continue to reduce the energy consumption of the building. The energy modeling and daylight modeling that we described in previous blog posts will continue in support of this goal.
  • Ongoing analysis of the carbon footprint of the building.
  • Development of the Urban Agriculture component of the LBC. Based on LBC requirements a significant amount of our site will need to be involved in food production. This is a very unusual design consideration and should make for a fascinating exploration.
  • Continued incorporation of principles of Biophilia into the design.
  • Much more materials research. There will be several students working over the summer to continue the excellent research work they conducted this spring.

It’s going to be a busy summer. The design team looks forward to presenting an update to the university community in September. In the meantime, we’ll provide regular updates on the blog.

Schematic Design & Energy Modeling

In high performance building design it is helpful, critical even, to start detailed energy modeling for the proposed design as early in the design process as possible. This allows the design team to use this modeling tool to influence the design process resulting in a more cost effective, optimized building design. Pathfinder developed the first energy model for Nuthatch Hollow during Schematic Design. Throughout the next phase, Design Development, the team will continue to update the model and use it to refine our design decisions.

One of the goals of the Nuthatch Hollow project is to be a “Net-Positive Energy” design. The project will use renewable energy on site to provide 105% or more of the annual energy that the project uses. Building simulation tools are used to help minimize energy consumption of the design and help achieve the Net-Positive goal. The first step is to enter the building geometry and floorplan into the model. Walls, windows, roofs and floors are entered along with their thermal properties. The building geometry is easily viewed and modified in a graphical interface, shown below.


Next, building loads are entered, consisting of occupants, equipment, lighting and hot water. The simulation represents one year of operation, so schedules are entered to describe how the loads vary hour-by-hour, as well as daily and monthly, including vacation and holiday periods per the Binghamton University school calendar. For example, a typical Monday schedule for occupancy is shown below.


HVAC systems (heating, ventilation and air conditioning) are entered into the model, along with thermostat schedules and the ventilation load (fresh air). Electric HVAC systems will be used to avoid using fossil fuels or other combustion. We are focusing on VRF systems (variable refrigerant flow – similar to heat pump systems). HVAC systems are controlled in the simulation to run only as needed to meet the building loads. The energy model provides detailed information about energy consumption of the proposed design. It is easy for us to make adjustments in the building loads, geometry and thermal properties, and HVAC system efficiency and controls, to see the likely impacts on energy and help us achieve our Net-Positive goal.

Daylight Analysis as Design Tool

Performance based design requires that a design team consider multiple factors simultaneously as they design a building. One of those factors is optimizing the building for daylighting. For Nuthatch the design team performed daylight analysis to help define both the form and orientation of the building and optimize window openings. We used the Honeybee extension for the Rhino plugin, Grasshopper to perform our analysis.


Our building is composed of two volumes, the volume enclosed by the existing building foundation and another volume containing the multipurpose room. For the volume defined by the existing building we primarily used the software to analyze window openings, since the shape and orientation of the space was defined by the existing building footprint. For the multipurpose volume we were able to do a more extensive analysis looking at shape, location, orientation and window openings.

The software was used to consider three key factors: Spatial Daylight Autonomy; glare; and Occupant Adaptive Thermal Comfort. Spatial Daylight Autonomy looks at the normalized daylighting in a space over the course of a year allowing us to understand which approaches have the best overall daylighting. We then look at the space during specific times of day and year to make sure there are not issues with glare. Finally, the Occupant Adaptive Thermal Comfort analysis uses ASHRAE Standard 55 thermal comfort model to show the relative comfort level in the space for each approach, which subsequently helps reduce the building energy consumption for heating and cooling.



A great benefit of a tool like Honeybee is the ability to run hundreds of iterations to quickly refine and test our approaches. The images included with this post show some of those iterations along with the analysis of the scheme as it is at the end of Schematic Design. As we move forward with Design Development we will continue to refine our window placement and shading strategies and test them using this analysis tool.

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