Green/Blue Roofing System Question Answered

 

GWPhius Senior Scientist Graham Wright weighs in on an interesting proposal for a green/blue roofing system and its feasibility for use on a Phius project.

The Question: “…The design team is considering a Green/Blue roofing system. Some of these systems / designs show rainwater being stored underneath the continuous insulation on the roof. We wanted to run these design concepts by you to understand what questions we should be asking and what information we should be gathering in order to model this, whether you have encountered this and have thoughts on how to model / approach this, and/or whether we should steer away from any of these designs altogether.”

The Answer: As far as I can tell, Green roofs and high insulation are not compatible, or, this is a research area.

The concept shown has only a thin layer of insulation. The Opti-Green system in the WUFI database is about R-3 overall. This research paper from 2012 looked at an R-22 roof.  

Green-Blue Roof Graphic

So, first thought: you probably could not do a large area of this and hope to meet the energy targets. It might be OK to experiment with it in a small area. They should ask if what is being proposed has any track record. Has this ever actually been built before in this climate?

Second thought: There is also clearly a tradeoff with the insulation positioned where it is. On the one hand, placing it above the water helps keep the water from freezing. On the other hand, how does the water get up through the insulation to the plants? If there are perforations, then the “fastener correction” calc should be done to derate the insulation. This becomes more troublesome the thicker the insulation is. Also, water flowing and draining away beneath the insulation will defeat its winter performance. This will happen whenever it rains enough during the heating season, and there should be another derating for that.  

Third thought: I think the idea of these is there is an evaporative cooling benefit in the summer. So it might make sense for a cooling-dominated building in the right kind of climate — e.g. one with warm summers but not too dry summers — so you get free rain water and don’t have to pump water up for irrigation. In terms of both energy savings and heat island mitigation, I think a foam-insulated and cool-membrane roof would compete very well with this concept and would be a lot lighter. If they are thinking of doing a whole roof this way, I would suggest doing a comparison to such a baseline case on both cost and simulated performance by WUFI Pro.

 

The article about green roof modeling mentioned in the WUFI help is here

Energy and Buildings

Volume 145, 15 June 2017, Pages 79-91

Energy and Buildings

A hygrothermal green roof model to simulate moisture and energy performance of building components

D.Zirkelbach S.-R.Mehra K.-P.Sedlbauer H.-M.Künzel  B.Stöckla

Phius Ventilator Certification Program: An Upcoming Comprehensive Evaluation Tool

The main goal of the Phius Ventilator Certification Program is to comprehensively evaluate heat-recovery and energy-recovery ventilators’ suitability for passive building applications.

Ventilator BlogDefining the end goal of the program was easy, but the path to it has not been. Our technical staff has been busy analyzing existing data, creating a new set of criteria, and tinkering to balance the stringency of the program with available test methods. The end result will be a comprehensive certification program that pairs useful performance data for energy modeling with Phius-specific endorsements for most types of ventilators.

The foundation of the Phius Ventilator Certification Program is the six categories for which it gives out endorsements: 

  • Thermal Performance & Climate Zone Endorsements
  • Electrical Performance
  • Air Quality
  • Defrost & Condensate 
  • Summer Bypass Mode 
  • Acoustics

Of those, only acoustics has non-critical endorsements, meaning that a product can miss out on certification if it does not meet minimum criteria in all these areas — except for acoustics.

The presence of those critical endorsements means it is a certification program and not “just” a rating system. But this program’s evaluation goes beyond a simple yes-or-no certification. Products can earn a variety of endorsements under each of the six categories mentioned above, including climate zone-specific endorsements. 

Another aspect of the Phius Ventilator Certification Program intended to ensure reliable data is its annual verification process. Units selected at random will be subjected to physical testing as a means of verifying that performance remains consistent. In order to make the program as fair and equitable as possible, Phius has developed its own methodology for selecting units for verification each year. The formula is such that products made by “high-volume” manufacturers will be selected more often than those made by “low-volume” manufacturers. 

Building a program of this scope has come with its challenges, but the technical team at Phius has remained committed to making the program comprehensive. This has meant figuring out ways to account for a wide variety of ventilator systems varying from small packaged units to large commercial components. As an all-encompassing program, the Phius Ventilator Certification Program will adapt as new ventilation devices are developed.

As with all Phius product certification programs, the ventilator program aims to collect performance data that can be used for energy modeling while also providing a comprehensive and consistent set of performance standards that can be used to compare products.

As Phius continues to bring passive building into the mainstream, we will continue to provide any and every tool possible to those willing to help. The Phius Ventilator Certification Program is one of the main product-related tools we are providing. We look forward to seeing its impact on the growth of passive building across the world.

Breakthrough Project Aims to Bring Flood of Zero-Energy Housing to Milwaukee

 

 

Shilpa 12Shilpa Sankaran is a consultant driving adoption of innovations in the built environment and the health of the planet, societies, and people. She is currently an advisor to the City of Milwaukee, who is spearheading a breakthrough public-private partnership in offsite affordable, zero-energy housing production. Previously, Shilpa was the Executive Director of the Net Zero Energy Coalition, co-founder of the REALIZE prefabricated zero energy retrofit model, and co-founder of ZETA Communities, a modular zero energy buildings fabricator in Sacramento.

In the wake of a global crisis, a cocktail of pandemic, economic distress, political turmoil, and heightened awareness of social inequity, we sit in the still point of opportunity for change.

Cue the City of Milwaukee. This city has seen its share of change — including economic and social trauma from the depletion of its manufacturing culture — and it has shown amazing resilience through grit and innovation. Now, we see revitalized and thriving new neighborhoods, innovation in water and sustainability, and new industries popping up throughout the city.

MilwaukeeMilwaukee, led by Mayor Tom Barrett and the City’s Environmental Collaboration Office (ECO), is spearheading a project that could bring back the original spirit of the city, and serve as a model for other cities around the country. The City is seeking a partner to locate a factory that will build zero-energy housing as part of public-private social enterprise.

On the surface, this may sound like just another construction solution, but Milwaukee sees it as so much more. This one solution will create income opportunities and green skills development for the residents of one of the most economically depressed areas in the country. These very residents will also have new home ownership opportunities, and will be able to proudly support their own health and the health of the planet with zero energy homes. Local manufacturing will take place in this same area — the 30th Street corridor — restoring a culture of industry, while revitalizing the neighborhood.

The goal is to target Phius Certification for all buildings, which requires certification under EPA ENERGY STAR, DOE Zero Energy Ready Homes and EPA Indoor airPLUS as co-requisite programs.

To attract an aligned partner, the City of Milwaukee is deeply committed to lowering barriers to entry and supporting the long-term success of a factory partner with financial, training, pipeline, and policy and codes support.

The first step is garnering industry interest through a Request for Information (RFI) which is due on July 12th. Later this summer, a Request For Proposal (RFP) will be issued, and the hope is to secure a partnership by the end of 2021 or early 2022. Following the design and construction of demonstration unit(s), the goal is to open the factory for full production by 2023.

If you are interested in participating in this process, please submit your Intent to Respond, and respond to the short RFI by July 12th. The RFI can be found here.

On International Climate-Specific Passive Projects

Andres-vert3Phius Certification Team Member Andres Pinzon, PhD, explores the process of passive projects being built outside of the United States.

“Qué es una casa pasiva?” reads the cover of the drawing set of the Merlot House, a project submitted by CPHC Ignacio López pursuing PHIUS+ 2018 certification in Baja California-Mexico. This project — the first in this country — adds to the growing interest of Phius certification across latitudes.

During a regular week at Phius, we move between reviews on different climate zones, building functions and building types, assessing data from residential and non-residential, new construction, or retrofit. 

At first sight, the path toward certification may look intimidating, and we at Phius know that. Our team offers guidance and support for project submitters, especially when working on their first projects (overseas or not). The reviewers go above and beyond in helping project teams meet the specific, wide-ranged, and performance-driven goals of their buildings. This process offers achievable steps for certification within the context of each project.

How does Phius do it? The process includes: rounds of review, real-time feedback, conference calls, online open resources, etc. Phius tailors this process by providing solutions in compliance with certification, looking for red flags, and pointing out paths to avoid. This allows us to work with clients, architects, engineers, building scientists, etc. on the critical aspects of certifying a project in a particular part of the world.

Here are some remarks from our experience working with projects submitted to Phius outside of the mainstream of US and Canada.

The first step is generally custom climate data, followed by calculating the project-specific performance targets. Using the appropriate climate data and performance targets are essential to accurately modeling and reducing energy loads. Phius generates custom climate datasets for project teams that accurately represent their current project’s location. For most locations, we have not had trouble finding a TMY3 station within a (80-km) 50-mile range.  

In addition to climate data, marginal costs of electricity ($/kWh) at the regional/national level are needed to calculate the custom space conditioning targets they will use for certification. With this, teams can begin to work on comprehensive design and energy modeling; aware of the demands and loads that are expected for their buildings. 

Phius has projects in places such as Japan, Colombia, Nigeria and Mexico, where Phius certification represents a third-party verification on a desired performance for energy use and high-quality housing (see post on Housing Equity). The accumulated experience of different situations helps Phius come up with new solutions for diverse challenges and pass that knowledge to teams in subsequent projects.  

For example, approaches on cooling and dehumidification seen in Phius projects in southern states can guide us on how to tackle larger demands and peak loads in projects in tropical areas of South America or Africa. We see this potential in aspects such as: the enclosure’s insulation and airtightness, shading dimensioning and optimization to avoid overheating, and the proper selection and sizing of mechanical devices.  

Energy and carbon saving targets in buildings and operational budgets are a global concern. However, some information might be lost in translation when moving between countries, languages, cultures, or systems of measurement. In this sense, Phius is working on expanding the limits on a technical language that might hinder the domain of Phius projects.

Phius’ CPHC training is also offered and taught in SI units. In this way, professionals abroad who are interested in earning this credential can have access to material on building science principles, design exercises, and software tutorials prepared in the metric system. Furthermore, WUFI® Passive, the energy modeling software used for Phius certification, allows users to easily toggle between SI and IP units any time during the process.

More actions are in development within the idea of expanding the Phius community abroad. It is exciting to see creative and innovative approaches, integrating different sorts of information to make a high-performance building, such as the “bilingual” drawing set from the Merlot house. I cannot wait to attend the breakout session on international climate-specific passive projects at PhiusCon 2021 to continue the conversation.

Phius and Housing Equity: We Can Do This

What do we mean when we say equity in housing? Is it providing a place for all unhoused populations to live? Is it creating enough resources so that everyone has housing security, no matter their class, race, or age? What about high quality housing?

Finch Cambridge, an affordable housing project that won Best Overall Project in Phius' 2020 Design Competion.

Finch Cambridge, an affordable housing project that won Best Overall Project in Phius’ 2020 Design Competion.

Homes and apartments built to the Phius standard are airtight, energy efficient, super insulated, and low maintenance. They are comfortable, quiet, and provide a quality of life. These dwellings provide hard-to-find clean, high quality air, because the ventilation brings in fresh, filtered air and exhausts the stale air, something the coronavirus pandemic has shown is essential to mitigate spread of the virus. Better indoor air quality produces better health outcomes for people with chronic conditions like asthma.

Does your definition of housing equity include the quality of housing? It does for Phius.

Comfortable, well-built, and sustainable homes do not have to be for only the upper class. This is a policy issue. The cities and states of our country owe it to low-income citizens to provide them with a home that keeps them safe, does not strain their finances, and improves their quality of life. Affordable multifamily passive housing has proven time and again that it can be achieved at the same cost as a less sustainable or less reliable home. Single-family homes are being delivered at costs that range from 5 to 10 percent more than conventional buildings. Everyone should live in housing that is reliable and resilient.

Affordable housing, how do we define that? Usually it means housing built for lower-income individuals and families, those on a tight budget. It should also mean housing that is affordable to maintain and to heat or cool. It is not affordable if the occupants have to make a choice between paying for food and paying their utility bills. Multifamily buildings built to the Phius standard use 40-60% less energy than a comparable building built to code, resulting in similar reductions to utility bills.

Homes built to the Phius standard are resilient and reliable. In 2021, the state of Texas froze when its power grid failed. The information from the passive houses we have from Texas show that the temperatures in the building never came close to freezing. Families would have been able to stay in their home and no pipes would have burst, saving hundreds if not thousands of dollars in repairs and replacement.

Imagine living in a home that maintains its temperature no matter the season outside; that weathers severe temperature swings, and costs you less money to live in. Did you feel your stress levels lower just a bit? Don’t your children deserve to live like that? Doesn’t everyone’s child deserve that? How about your parents too?

The infrastructure can be created. This country can do it for its people.

How do we do this? Reach out to your city council, to the people who represent you on the most local level, to educate them about the benefits of passive building to the community.

Many states, like Massachusetts and New York, already have incentives for energy efficient homes. In Pennsylvania, 7 Phius certified projects, representing over 350 units of affordable housing, have been built and shown to be cost-effective. Incentives in Massachusetts have led to the construction of 8 Phius low-income projects with almost 550 units. These projects have come in at between 1.5% and 2.8% above building code. Massachusetts, building on this success, just passed a progressive energy bill that will push it’s already progressive buildings sector forward.

The change is possible and we all deserve it, including those who never even seem to get a piece of the pie.