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Tag: High-Performance Construction

Best Practices for Designing & Installing VRF Systems in Commercial and Multifamily Applications (Part 1)

With LL97 fines around the corner, building owners and managers are looking to reduce greenhouse gas emissions. To do so, building systems will need to rely on an increasingly green electric grid rather than fossil fuels.

And as we look to electrify our buildings’ heating and cooling systems, Variable Refrigerant Flow (VRF) systems have emerged as one solution. With buildings increasingly turning to this technology, we are sharing our current best practices for designing, installing, and operating VRF systems to help everyone — from design engineers and developers to installers and building operators — learn more about the nuances of VRF.

These best practices are based on manufacturers’ literature, ASHRAE and IECC standards, conversations with field technicians, design engineers, building operators, and manufacturers’ representatives, as well as Steven Winter Associates’ extensive functional testing experience. While the focus is intended to be large VRF systems ( >5 tons), many of the best practices are also applicable to smaller mini-split or multi-split systems.

Common terms used throughout this post are defined for those new to the topic and can be found by scrolling to the bottom of the blog.

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Passive + Adaptive Resiliency: A Recipe for Sustainability

The need for sustainably designed buildings and infrastructure is critical as extreme weather patterns and natural disasters resulting from climate change persist. One of the truest measures of sustainability in this case is resiliency. How the site, the building, and the systems respond to an extreme weather event or other consequences of climate change can determine its livability. For green building, resiliency can be passive or adaptive, meaning reactive to these types of events or proactive in surviving them.

The recent events in Texas highlight the need at a national level for building and infrastructure resiliency.  Sudden freezing temperatures forced the grid to shut down and left millions of residents without power. The failure of uninsulated water pipes and lack of winterization throughout the energy supply could (and should) have been remediated decades ago.  In fact, a commissioned report released after similar blackouts 22 years ago recommended the incorporation of resilient designs into the system by “installing heating elements around pipes and increasing the amount of reserve power available before storms”. Michael Webber, an energy professor at the University of Texas said: “We need better insulation and weatherization at facilities and in homes.. There’s weaknesses in the system we [still] haven’t dealt with.”[1] Now, politicians and leaders are calling for more of these passive solutions that may be too little too late on such a massive scale.

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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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Comprehensive Heating Upgrades for Two-Pipe Steam Systems

Most people who have lived or worked in a steam-heated building are familiar with the typical occurrences of uneven heat (underheating/overheating), banging pipes, and having to open windows all winter long.  Not only are occupants uncomfortable, but the heating bills are high as well. Balancing these systems is a huge opportunity for energy savings. It is important to point out that the root of the issue is in the distribution system, and it’s that distribution system that needs to be fixed. The steam traps are the weakest –link and when they fail, residents lose the ability to control the amount of heat delivered. This in turn makes the space uncomfortable and results in the necessity to open windows and waste fuel. The steam traps are supposed to be replaced building-wide every three years to catch broken traps, but due to the expense and logistics of such a task, this is rarely actually done.

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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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How to Talk Windows with a Passive House Nerd

Before we get into this topic, please take a few seconds to consider the following questions:

  • Do you plan to work, or have you ever worked, on a Passive House building? (If not, the rest of your answers are probably no.)
  • Has your Passive House consultant ever told you that the window U-Value you provided “won’t work in their energy model?”
  • Has your Passive House consultant ever told you that your window “doesn’t meet the comfort criteria?”
  • Have you ever scratched your head when someone asked you to provide the “Psi-spacer” for your window?

If you answered yes to two or more of these queries, please read on. If not, you’ll still learn some useful information, so why not continue?

If you’re still reading, then you are probably somewhat familiar with a “U-Value” and you may know what “SHGC” means. If not, no worries. This article will explain both, and by the end you’ll be able to talk about these terms with most Passive House nerds.

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Net Zero and Electrification

Net zero” can mean a lot of different things depending on what you choose to measure – zero energy usage, zero carbon emitted, zero lifecycle impact, etc.

At Steven Winter Associates, Inc. (SWA), we work with clients who are approaching net zero from different angles: driven by institutional goals, climate concerns, marketing campaigns, and connecting with municipal emissions targets. One thing we see over and over is that super high performance is difficult to achieve, but with a key simplification – there are not many ways to do it. All roads may lead to Rome but the closer you get, the fewer roads there are to take.

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Choosing Insulation for Carbon Value – Why More is Not Always Better Part 2

In Part 1 of this blog post, we highlighted two of the most commonly used insulations in the U.S.– XPS board and closed-cell polyurethane spray foam – and noted that they are produced with blowing agents (HFC-based) that are putting more carbon into the air during construction than they save during building operation for many decades. We left you with a question: if we don’t use these insulations, how can we make up for the loss of the helpful qualities that has made us dependent on them?

Insulation Alternatives

One part of the answer comes from the development of new materials. In Europe over the last decade, Honeywell developed a new blowing agent, a hydro-fluoro olefin (HFO), which claims a global warming potential (GWP) of less than one, which is less than that of carbon dioxide.  First in Europe, and now in the U.S., manufacturers such as Demilec and Carlisle are coming to market with a closed-cell polyurethane spray foam that uses this blowing agent instead of the HFCs that carry a GWP of well over 1,000. These spray foams have a slightly better R-value  than their high-carbon predecessors, and otherwise have the same qualities that make them useful in multiple contexts – air/vapor barrier capability, conformance to irregularities and penetrations, etc.  However, they also have many of the same downsides – high flammability, potential (and not completely understood) off-gassing post-application, and the basic fact that they are petroleum products.

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Passive House: An Alternative Compliance Path to Toronto Green Standard Tier 3

It is clear to see that the Passive House (PH) standard is here to stay! Across North America, more States, Provinces, and Municipalities are integrating PH into their building standards. One of the more recent adopters is the City of Toronto. In the most recent version of the Toronto Green Standard (TGS), the PH standard is offered as an alternative compliance path to TGS Tier 3, and with this alternative compliance path one obvious question comes to mind: What is the major difference in required component efficiency for a multifamily building in Toronto that is looking to meet either the PH standard or TGS Tier 3?

The PH standard is performance-based and is focused on decreasing whole building energy demand, improving building durability, providing optimal occupant thermal comfort, improving indoor air quality, and reducing carbon emissions. The PH standard reduces building operation costs, decreases carbon emissions, and supports an improved indoor environmental quality for building occupants. The TGS has similar goals and benefits when compared to the PH standard, and there are some obvious synergies in the program design between TGS and PH. The tiered energy category in the TGS takes a similar approach to PH by offering an annual budget for three different categories. For PH you must comply with a total energy budget for annual heating demand, annual cooling demand, and total source energy use intensity. Similarly, but slightly differently, the TGS offers a budget for total site energy use intensity (TEUI), annual heating demand or Thermal Energy Demand Intensity (TEDI), and the additional category of Greenhouse Gas Intensity (GHGI). In both standards, the path to compliance is non-prescriptive and designers can implement a variety of component efficiencies and system options. See table 1 and 2 below:

 

Image of passive house criteria standards

Table 1: Passive House Standard Criteria

Second image of passive house criteria

Table 2: Toronto Green Standard Tier 3 Criteria

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5 New Year’s Resolutions for a High-Performance Year

We took some common New Year resolutions and put our SWA spin on them. This year, make resolutions to improve the built environment in 2020!

 

  1. Go on a (Carbon) Diet – diets are difficult, but as with all things, moderation is key. Reducing operational carbon use with super-efficient buildings is only part of the equation. We also need to understand the full Life Cycle of carbon use including building materials and products. Fortunately tools such as EC3 are making these analyses easier to understand; and products, including lower carbon insulation options and lower carbon concrete, are becoming readily available.
  2. Quit Smoking – enforcing no smoking policies is one of the best strategies to improve the health of all building occupants. If you do allow smoking, make sure you develop a good fresh air strategy and compartmentalize your units with a good air barrier. And check out more of our strategies for healthy indoor environments.
  3. Save More Money – lighting provides a significant area for savings. Sure, LEDs are great, but efficient design also means considering lighting power density (LPD). High efficiency fixtures placed in high concentrations still use a lot of energy and can result in over-lit spaces, which drive up upfront and operating costs. Lower your bills and the harsh glare with a smart lighting design.
  4. Travel More – seek out hotels and restaurants that people of all abilities can navigate with ease. Access Earth is an app that tracks the accessibility of public spaces worldwide to help take the guesswork out of accessible accommodations in new locations.
  5. Learn a New Skill or Hobby – looking to expand your horizons? Check out SWA Careers and join our team of change-makers to help develop and implement innovative solutions to improve the built environment.

 

 

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