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Air-Source Heat Pumps in Homes: Step #2 – Pay Attention to the Envelope

This is part of a series; see the first post here.

This shouldn’t be news to anyone:  In most homes, insulation and air sealing are the most effective ways to improve comfort and reduce heating and cooling costs.

This holds true regardless of heating systems or fuels used. So why is it emphasized even more when talking about heat pumps and electrification? Four reasons.

1.  Heating System Capacity and Cost.

Say your home has a design heating load of 60,000 Btu/h.[1] If heating with fuel, you’ll need a furnace or boiler with a capacity of at least 60,000 Btu/h. These are easy to find. (In fact, you may have a hard time finding heating systems with capacities lower than this.) Air-source heat pumps, on the other hand, have smaller capacities. I don’t think you’ll find an ASHP with heating output of 60,000 Btu/h at cold winter temperatures. So to meet this load, you’ll need multiple ASHPs. And that gets pricey.

Even if you are not talking about multiple heat pumps, a 3-ton[2] heat pump is quite a bit less costly than a 5-ton heat pump. Costs of heat pumps scale more dramatically than costs of boilers and furnaces. So lower heating loads → fewer, smaller heat pumps → lower upfront costs.

Spray foam insulation

Spray foam in an attic – one of many ways to insulate and seal.

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Choose Your Adventure: Constructing New vs. Adapting Old

Carbon emissions from new construction graphTo meet the goals of the Paris Climate Agreement, we must make decisions that will result in the greatest near-term carbon savings. This means taking into account both embodied carbon—those upfront emissions associated with the extraction, manufacture, transportation, and assembly of building materials—as well as the carbon that’s emitted over the course of the building’s operational phase.

We can build a high-performance building with very low operational emissions, but if its embodied emissions are so high that even if it’s a net-zero energy building (meaning it has net-zero operational energy consumption) it would take decades for the building to reach net-zero carbon (meaning it has net zero whole-building lifetime carbon emissions), we’re not actually helping to solve the critical issue of near-term carbon.

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Utilizing Enterprise Green Communities to Drive Equity in Affordable Housing

EGC logoIs Sustainability only for the wealthy? While staring at the double-digit price of organic tomatoes at the local farmers’ market I am inclined to think sustainable is synonymous with exclusive. Unfortunately, many things labeled “sustainable” or “eco-friendly” seem not to be within everyone’s budget. A society where the cost of a Tesla is the average annual income of a household easily convinces us that making sustainable choices comes with a cost many can’t afford.

The ”green” housing industry is no different. Walkable and well-connected neighborhoods, where residents can enjoy abundant services are often the pricey neighborhoods. Toxic-free natural materials, daylight, fresh air, and even living green walls fill the homes of the wealthier and healthier tenants, while high-efficient mechanical systems and solar panels provide (almost invisible) energy savings as compared to their sky-high rents.

On the other side, low-income families are often located in neighborhoods at the edges of cities where community services and fresh healthy food are out of reach except by driving, and where parks and options to catch some fresh air are far and rare. Here the apartments are more likely to be exposed to toxic materials, increasing chances to develop asthma or other diseases. Energy bills are often high with little opportunity to get any lower by using newer energy-saving appliances and equipment.

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Staff Profile: Minaiel Shoaib – Building Systems Analyst

Each day, SWA employees collaborate to create more sustainable, efficient, healthy, and accessible buildings. This holistic approach to the built environment necessitates talented teams with a wide range of specializations. (Want to join us? Check out the open positions on our Careers page!)

For our second staff profile, we interviewed Minaiel Shoaib, a Building Systems Analyst on our BODE (Buildings Operation, Decarbonization, and Efficiency) team. Minaiel is based out of our New York City office and has been at SWA for 1.5 years!

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Air-Source Heat Pumps in Homes: Step #1 – Be clear about goals

This is part of a series; see the first post here.

Building new homes that are all electric makes TONS of sense. I’ve written about that before. Electrifying existing single-family homes, however, is not necessarily straightforward. Many state and utility programs in the Northeast[1] offer hefty incentives for air-source heat pumps (ASHPs), but fuel-fired systems are often left in place and used as the primary heating system. Clearly, when that’s the case, carbon emissions are not reduced much. Other programs are pushing completely electrifying homes and removing fossil fuels, but these programs are not gaining all that much traction.

This may seem obvious, but it’s important to consider homeowners’ goals and desires when installing heat pumps in homes. I don’t necessarily see this considered by policy makers and electrification programs, and I think it’s a big disconnect. Programs and policies are focused on the big picture (appropriately) and generally want to reduce/eliminate fossil fuels to help meet carbon reduction goals. What homeowners want can vary like crazy.

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Trends in Healthcare: Hospital Gardens

“Trends in Healthcare” is a recurring series that focuses on exciting new designs and technologies we’re seeing in healthcare projects and provides best practices on how to ensure that these latest trends are accessible to persons with disabilities. We build on the wealth of knowledge we gain from working with healthcare design teams, construction crews, and practitioners to provide practical solutions for achieving accessible healthcare environments.


Accessible courtyardAccess to nature is known to promote healing and improve mental and physical wellbeing. The sights and sounds of the natural world have been proven to relieve anxiety, an attribute that can be immensely impactful in a hospital environment where patients, visitors, and staff experience increased stress on a consistent basis. With this in mind, hospital gardens that provide much needed respite have become an essential feature in many healthcare facilities. Even in hospitals built in places like New York City, where space is at a premium, healthcare owners and designers are prioritizing the integration of gardens and other natural spaces into facilities.

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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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Air-Source Heat Pumps in Homes: Soup to Nuts

As I’ve written in several posts [1], electrification is all the rage. Modern air-source heat pumps (ASHPs) are fantastic technologies, and they can provide reliable, efficient, clean, affordable, and sustainable heating and cooling when done well and in the right application. I worry that these caveats are too often glossed over. I’ve also seen really bad heat pump installations, and I think it’s easier to screw up a heat pump than a boiler or furnace.

ASHPs on the exterior of a home

Three ASHPs at a home

This post is an overview of the process I suggest for good ASHP installations. I’ll be doing a post for each of the steps here, but this first post is an outline of the whole process because I believe the whole process is really important. The focus here is on homes, mainly in colder climates, and I’m not talking about VRF systems. I use the generic second person, so “you”  can refer to different people in different steps.

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Innovations in Accessible Products 2021

Our accessibility consultants are constantly on the lookout for new products that will make it easier for our clients to comply with accessibility criteria while meeting their overarching design goals. As manufacturers become more familiar with accessibility requirements under applicable federal, state, and local regulations and building codes, new or modified products continue to emerge, making compliance simpler and more stylish.

Here are just a few examples of accessible products that we have been recommending…

SafePath EntryLevel™ Landings

Safepath

SafePath EntryLevel Landings provide an affordable and easily customizable option to address non-compliant level changes at doors.

One of the most common issues we see in remediation projects, especially as a result of litigation, is a non-compliant level change at exterior doors. Very often, a step up of more than ½ inch is provided from the exterior to the interior surface, resulting in a barrier to access for a person who uses a wheelchair or other mobility device. SafePath provides a range of customizable ramps and reducers to help overcome vertical barriers to access at interior or exterior conditions. One of the product lines we have frequently recommended is their EntryLevel™ Landings. The product provides a compliant ramped transition (1:12 max) along with a level landing (1:48 max slope in any direction) to accommodate the required maneuvering clearance at doors. Because the landings are fixed in place and easy to customize, they provide a great option for clients looking to create an accessible building entrance.

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Staff Profile: Joe Andracchio – Senior Sustainability Consultant

Each day, SWA employees collaborate to create more sustainable, efficient, healthy, and accessible buildings. This holistic approach to the built environment necessitates talented teams with a wide range of specializations. (Want to join us? Check out the open positions on our Careers page!)

In our first staff profile, we have Joe Andracchio, a Senior Sustainability Consultant on our Residential Buildings Services group. Joe is based out of our Washington, D.C. office and has been at SWA for around 4.5 years. He is also a licensed Professional Engineer in the state of Maryland!

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