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Efficiency and Health: Prioritizing Occupant Health and Wellbeing in High-Performance Buildings

We like to say that a building is not sustainable if it does not sustain the health and wellbeing of all its occupants. This includes considering how the materials, technologies, and building systems affect indoor air quality, comfort, and the physical and mental health of those utilizing the space.

In our post-COVID world, it also includes how a building can protect its occupants from viruses and other airborne illnesses.

We’re sharing real-world examples of how SWA consultants have helped to mitigate potential negative impacts on occupant health in high-performance buildings. (more…)

Your Top 10 Passive House Questions, Answered – The Long-Awaited Part 2

On the very first episode of Buildings + Beyond, Passive House pioneer Lois Arena answered the most common questions asked about meeting the high-performance requirements of the Passive House standard. You loved the episode—it’s one of our most popular of all time—and we loved recording with Lois. So, 6 years later, we decided to record a highly anticipated follow-up episode.

Listen as host Robb Aldrich poses the same 10 questions from the original episode, and a few new ones, to Lois and Dylan Martello—who both work on first-of-their-kind, largescale Passive House projects at Steven Winter Associates. What answers have remained the same, and what has changed in the last 6 years?

Click here to listen to the original episode.

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What Can Go Wrong with Passive House Ventilation Systems—and How to Prevent It

The envelope of a Passive House building is designed to be significantly airtight. Mechanical ventilation systems introduce fresh, filtered air and exhaust stale, contaminated air 24 hours a day—which is extremely important in maintaining optimal indoor air quality and occupant comfort.

As the saying goes, build tight and ventilate right.

When ventilation systems are designed correctly, but installed, commissioned, or operated incorrectly, the system ends up being leaky and inefficient and uses more energy than expected.

Project teams for Passive House buildings must find solutions for these implementation and commissioning hurdles, or the potential energy penalty can adversely effect the building’s high-performance design intent.

What happens when a Passive House construction expert and a commissioning engineer collaborate to find a solution to common ventilation system issues that cause excess energy use? We, the authors of this blog post, did just that!

Keep reading to learn about common construction issues with Passive House ventilation systems and five lessons learned based on our experiences in the field. (more…)

Sustainable Buildings Are Healthy Buildings: How to Design and Maintain a Healthy Built Environment

What is a sustainable building? We know it must be an energy-efficient, high-performance building and emit as little carbon as possible to protect the environment. But a sustainable building must also be a healthy building that protects people and communities.

A building can’t be considered sustainable if it doesn’t sustain the physical and mental health of all its intended occupants and sustain the community around it.

Healthy buildings require a holistic approach that accounts for how every building material, system, and technology affects the wellbeing of occupants.

This is an important topic at SWA, so we asked our interns to explore it! They talked to our experienced building systems, sustainability, and Passive House consultants and put together this blog post as a resource on designing and maintaining a healthy built environment.

Keep reading to learn more about the following considerations for healthy buildings:

  1. Occupant comfort and productivity
  2. Optimal indoor air quality (IAQ)
  3. Ventilation system upgrades in existing buildings
  4. Healthy building certifications (Fitwel, WELL, etc.)
  5. Building operations and maintenance staff training

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(ENCORE) Why is Kitchen Ventilation So Important? With Dr. Iain Walker from LBNL

We first released this episode in April 2019. Since then, our topic of discussion with Iain has only become more relevant. We recently caught up with Iain and have some updates to share, which are reflected in the resources below and at the end of the episode. Enjoy!


When you fire on a stove-top burner, whether it is electric, gas, or convection, many byproducts are released. This increase in moisture, gas, and other particulates is not only detrimental to the health of a building, but dangerous for human health as well.

To advance our knowledge on this topic, we invited building scientist and ventilation expert, Dr. Iain Walker, from Lawrence Berkeley National Laboratory (LBNL). Dr. Walker discusses strategies for controlling byproducts associated with cooking by focusing on kitchen ventilation.

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Designing for a Post-COVID World with Passive House

Passive House design for large multi-family buildings aligns with and builds upon industry guidance for mitigating the spread of infectious diseases.

As the world continues to be turned on its head by the impacts of COVID-19, the building industry has been scrambling to respond, encouraging designers and building operators to learn about how their buildings are being ventilated. Industry experts have produced an array of documents and reports outlining guidelines for reopening buildings safely while minimizing the risk of transferring infectious disease. Much of the focus of this guidance has been on using mechanical ventilation and proper air distribution to dilute contaminant levels in spaces and minimize the spread of viruses. The American Society of Heating, Refrigeration and Air-conditioning Engineers (ASHRAE) has produced a significant amount of guidance for designers. One of their main documents, produced in April, is the “ASHRAE Position Document on Infectious Aerosols,” which provides useful information for how buildings should be designed and operated in response to a pandemic. However, it has prompted questions from design teams about how this might conflict with the goals of very low energy buildings, such as Passive House (PH). This blogpost is written as a response to some of these questions and to highlight the benefits of Passive House design in light of recent recommendations by groups like ASHRAE.

Benefits of Passive House for Mitigating COVID Transmission

The following are some of the benefits of Passive House design for multi-family buildings compared to code requirements as well as some additional guidance for how to design to mitigate virus transmission.

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Electrifying Central Ventilation Systems in Multifamily Buildings

A common strategy to provide ventilation in multifamily buildings is to design a central roof-top air handler that distributes outdoor air to each unit. The energy cost for this system, which commonly uses natural gas for heating for either a gas furnace unit or hot water from a central boiler is paid for by the building owner. However, there is another option – VRF[1]. With the unprecedented rise of VRF technology in the last decade combined with regulations such as New York City’s Local Law 97 of 2019[2] (carbon emission penalty), the industry is taking a giant leap towards building electrification. There are always questions and concerns raised against building electrification ranging from initial cost to operating cost to reliability of the VRF technology. From the owner’s perspective, the biggest question is usually surrounding the operating cost of an electric system compared to a natural gas system for heating, but the cost of ownership must consider multiple energy metrics. I was curious to understand the impact on various building energy profile metrics associated with a Dedicated Outdoor Air System (DOAS) using the conventional gas fuel source vs. the latest VRF heat pump technology using electricity in a multifamily building. The findings of this investigation challenge the deep-rooted notion that electricity, being more expensive than natural gas per BTU, will always cost more to operate.

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The Great Indoors: Creating a Healthier and Safer Built Environment

Image of elderly couple sitting on a bench laughingAs humans, we spend a lot of time indoors. Studies by the U.S. Environmental Protection Agency indicate that under normal circumstances the average American spends over 90% of their life indoors. With the spread of COVID-19 and widespread voluntary and involuntary quarantine, the rise of work from home policies and new direction to social distance has resulted in a further increase to the amount of time we spend indoors. Now more than ever, people are cognizant of the air they’re breathing and the surfaces they’re touching. The buildings that we live, work and play in impact our physical and mental health. With certain building and design considerations, we can make these impacts beneficial.

We recruited some experts at SWA to fill us in on the various considerations when it comes to the health and comfort of a building, as well as some certifications that assure these considerations are met.

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It’s Time to Focus on Our Schools

If you are a parent like me, I am sure you cherish your kids and seek to offer them the best opportunities in life. I even moved to a different school district. And, while the education is top-notch in my town, I have come to realize that it really doesn’t matter what school district you are in…all our schools need help. I am not talking about smaller class sizes, better pay for teachers, after-school programs, and more school supplies, although those are important. School buildings need attention. With budgetary pressures, a lot of maintenance and repairs are being deferred and schools are not aging well. Whether it is repairing existing systems, replacing systems at the end of their useful life, renovating, or building a brand-new school to service your community for future generations, advocate for your Board of Education (BoE) to think holistically about improving the conditions for our children.

Why My Call to Action?

This year I was asked to join our elementary school’s Tools for Schools committee, which is tasked with implementing an indoor air quality (IAQ) management plan. This experience gave me an opportunity to get involved and provided me insight into the school’s systems and the operations and maintenance (O&M) processes that were in place.

Unfortunately, at the start of the 2018 school year, mold issues were identified in our local middle school and the building was closed. In fairness, I quickly realized that buildings were outside the BoE members’ knowledge base. Afterall, they are educators, not facility managers or building scientists. They sought outside consultants but didn’t know the right questions to ask. After some time, the BoE decided to get input from local experts in the community. Fortunately, we have several experts (including me) who were willing to volunteer their time. As part of a task force, we laid out a strategy to remediate the mold issues in the school and to implement short- and long-term repairs to minimize/eliminate water incursion and elevated moisture issues within the building.

I am not saying you must get involved at this level, but I do encourage you to attend a BoE meeting and start asking questions related to IAQ. Ask if the school has deferred maintenance needs and if/when these are being addressed in the annual budget. Ask when (if) comprehensive physical needs assessments and energy audits were performed on all school buildings. Educate yourselves; then help educate your BoE and your community on IAQ guidelines for schools. Here are some great resources:

How Can SWA Help?

In working with schools, I have learned that one of the greatest challenges school decision-makers face is not knowing where to turn for support and guidance. Steven Winter Associates, Inc. (SWA) has been working to improve educational facilities for decades. Whether you have questions related to mold, moisture, comfort, absenteeism, accessibility, high utility bills…on up to zero energy design and progressive learning environments, SWA can support you. Here is just a sample of past school projects that SWA has worked on:

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Establishing Moisture Control in Multifamily Buildings

Most of us are familiar with the feeling of a humid apartment after taking a hot shower. Some of us kick on an exhaust fan, perhaps un-fog the bathroom mirror, or even open a window to get the moisture out. Domestic moisture generation—moisture from human activity—is a major factor driving the humidity levels in our residential buildings, especially in super air-tight, Passive House construction. Before diving into just how much of an impact domestic moisture has in our buildings, let’s first look at average daily moisture generation rates of a typical family of three[1]:

  • breathing and transpiration—6 to 9 pounds of water vapor/day;
  • 10-minute shower in the morning for each individual—3.6 pounds of water vapor;
  • cooking fried eggs and bacon for breakfast—0.5 pounds of water vapor;
  • cooking steamed vegetables with pasta for dinner—0.5 to 1.0 pounds of water vapor; and
  • one small dog and a few plants around the house—0.5 pounds of water vapor/day

This brings the daily total to 11.1 to 14.6 pounds of moisture generation per day, or about 1.5 gallons of liquid water.

Where does all of this moisture go? In a typical code-level apartment building with moderate to high-levels of air leakage, water vapor has two year-round exit pathways: exfiltration through the façade and dedicated kitchen or bathroom mechanical exhaust. Additionally, in the summer, moisture is removed via condensate from the cooling system.

Let’s now put this in the context of a highly energy-efficient apartment with very low levels of air leakage (about 5 to 10 times less than the code-compliant unit), and balanced ventilation with energy recovery. The first means of moisture removal, façade exfiltration, is virtually non-existent given the building’s superior air-tight design. Next is mechanical exhaust ventilation in the kitchens and bathrooms. Because the unit has balanced ventilation and energy recovery, the exhaust air stream in a Passive House project typically passes through the energy recovery core. Depending on the core selection, a large percentage of the interior moisture may be retained in the apartment air despite the constant mechanical air exchange.

There are two basic types of cores:

  • Heat recovery ventilator (HRV) in which a certain percentage of sensible heat is recovered (transferred from the exhaust air stream to the supply air stream) while no moisture is recovered.
  • Energy recovery ventilator (ERV) in which a certain percentage of sensible heat and a certain percentage of moisture in the air is recovered.

To fully understand this issue, Figure 1 breaks break down the moisture-related pros and cons of ERVs and HRVs in the context of a high-density, Passive House building.

  ERV HRV
Pros Summer – prevents high exterior air moisture load from being supplied to interior air; cooling loads are minimized Winter – flushes high internal moisture load out of building; humidity levels reduced
Cons Winter – if internal moisture generation is high, interior moisture load is not flushed out of apartment; humidity levels increase Summer – allows exterior air moisture load to be supplied to interior air: cooling loads increase

Figure 1. Moisture related pros and cons with ERVs and HRVs in high efficiency, airtight construction

 

Traditionally, the key factor in deciding between an ERV or HRV for a high-efficiency building has been the project’s climate. However, as internal moisture loads begin to exceed exterior moisture loads in high-density projects, the decision between ERV or HRV must be looked at more closely for each project regardless of climate.

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