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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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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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Call to Action: Voting Open Until December 6th on the Changes Proposed to the 2021 IECC

ICYMI: The code change proposals for the 2021 IECC are open for voting by Governmental Member Voting Representatives (GMVR) from Monday, November 18th through Friday, December 6th, and your vote is instrumental in making buildings consume less energy! [Need a quick refresher on the code process? Check out our blog post here!]

Does your vote even matter?

Overall, there are not actually that many voters on a given proposal. In the energy proposals, last cycle, it ranged from about 200-400 voters per proposal, even though there were a total of 1,247 voters on the Group B codes, which includes the IECC.

IECC voting numbers

So a small handful of voters can entirely shape the future of the energy codes that dictate how energy efficient our buildings will be! If history repeats itself, while some online voters tend to align with the Committee, many online voters align their votes with those cast by their fellow ICC voters at the Public Comment Hearings. This happened 81% of the time in 2016. Unlike 2016, in this cycle all the electronic votes cast during the Public Comment Hearings will be rolled into the online vote tally (although those voters can still change their vote).

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Zero(ish) – Waste Living

In a world where everything seems to be packaged in two layers of plastic, where we are encouraged to constantly discard items to make room for new ones, and where social media drives our desire to consume the newest trends, it can seem impossible to reduce our waste. Living a zero-waste lifestyle seems almost too overwhelming. I find myself wondering, “How can I possibly reduce waste when industries target consumers to do the opposite?” and “Even if I do make changes in my own habits, is it enough to make a difference?

I struggle with the same paralyzing vastness that Jonathan Chapman mentions throughout his book Emotionally Durable Design. Paralyzing vastness describes the tendency to do nothing when a task seems too large to conquer, instead of taking smaller steps. In the past, the seemingly vast nature of zero-waste living discouraged me from doing anything beyond entry-level recycling, but I realized that minimizing my waste is something worth tackling. Therefore, I will be sharing some ideas for working towards a zero(ish)-waste lifestyle — because going from zero to one hundred, or in this case one hundred to zero can be scary — and I’ll include my experience implementing a few of the ideas myself.

WEEK ONE: Apartment Composting

In blogs and articles that speak on behalf of zero-waste living, the importance of sharing with others and asking for help getting started is most frequently emphasized. For example, my apartment complex does not offer any composting services, but the SWA office does (yay sharing!). For week one, I started composting and designated two small resealable containers — one for food waste, and another for paper towels — that are now living on my kitchen counter. I intended on utilizing these two bins throughout the week, and then bringing them to the office for a dump. If you have the ability to start your own compost bin, that’s great too.

While using paper towels throughout the week, I felt less bad about it knowing that they wouldn’t be going into the landfill, but I developed some questions: If I use the paper towel with cleaning supplies, can it be composted?… Is it worth collecting small bits of food waste when I could just eviscerate them in the garbage disposal?… Are garbage disposals bad for the environment and/or do they affect the energy utilized for wastewater treatment?

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Choosing Insulation for Carbon Value – Why More is Not Always Better Part 1

SWA’s Enclosure Group is acutely aware that insulation is the most important single material choice to maximize the enclosure’s thermal resistance over its operational life. Many of us in the building industry believe that, combined with a good continuous air seal, the highest insulation value makes the greenest enclosure, helping to reduce a structure’s carbon footprint and combat climate change. It may come as a surprise, then, that some of the most commonly used insulation materials are so carbon-heavy to manufacture and/or install, that for many decades they wipe away the carbon-energy savings they are supposed to provide.  The following is a detailed discussion of how and why this is, and what the industry is doing to change the equation.

Embodied vs. Operational Carbon

The built environment looms large in the climate picture, because almost 40% of the total carbon put into the planet’s atmosphere each year is attributed to buildings. Over the past 30 years of green building, we have overwhelmingly focused on operational carbon – the carbon that buildings emit as they are being used. Only recently have we begun to focus on embodied carbon – the carbon that goes into constructing buildings, which is typically far greater than the energy saved in the first decades of operation. Changes in energy codes are aimed at operational carbon, and even those organizations and standards that have been at the forefront of promoting sustainable building [LEED, PH] have not been quantifying or limiting embodied carbon, although they bring attention to it.

The Time Value of Carbon

Assuming that a building stands for many decades, or even centuries, its operational carbon will eclipse its embodied carbon over its lifetime, and therefore when the building’s carbon Life Cycle Assessment (LCA) is calculated, operational carbon savings will be more important than embodied carbon saved/spent in the long run. Why does embodied carbon deserve equal weight with operational carbon? Because of the total global carbon emissions from buildings, 28% is pegged to embodied carbon. That’s already a large percentage, but when you consider the near term, the first 30 years of a building’s life, the percentage jumps to about 50%. In effect, every new building is in carbon debt upon completion due to the huge amount of carbon emitted  in order to construct it., And in order for the climate to benefit from the energy savings provided by a well-insulated and sealed enclosure and a high efficiency energy system, the building needs to last and be used for a very long time. The problem is that we may not have 30 years, let alone 60, to pay off that carbon debt.

In the first 30 years of a building’s operational life, 50% of its total carbon emissions are still due to embodied carbon (Source: Architecture 2030)

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Electric Cars: Are They Better for Your Pocket and the Climate Right NOW?

Last week, I read a blog post from Connecticut Fund for the Environment President Curt Johnson, and he reaffirmed what I already expected: my next car will likely be an electric vehicle (EV). I currently drive a Toyota Prius hybrid, but when I bought it in 2013, the price to purchase and to operate an EV did not work out, so I chose the Prius, which has very reliably achieved 50 mpg over the last six years.

As an engineer who admittedly knows nothing about cars, I feel like the information out there on EVs is either slightly biased (i.e., published by EV manufacturers) or not transparent enough with the math to convince me. So I set out to create a blog post that was unbiased and transparent. I liked this one from Tom Murphy, an associate professor of physics at the University of California, San Diego, so hopefully I’m making it a bit more user-friendly and applicable to your current/local situation.

I just wanted to know two simple things (and admit to ignoring a long list of other factors that influence the type of car most people will choose to drive):

Number 1: At what gas price is an EV cheaper to drive per mile?

Number 2: While EV tailpipe emissions are zero, is my local electric grid clean enough that it’s a good idea, right NOW? I know my next car will be electric, I just don’t know WHEN the grid will be clean enough that it’s better for the environment for me to switch.

When I began writing this article, I had no idea what the answers would be.

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Become a Carbon Hero with Five Easy Tactics

Before you can really dig deep into the advanced design concepts of embodied carbon analysis and whole building energy modeling, you must first perform some bare minimum prep work. An easy way to get the pre-schematic plan up on its legs quickly is to add qualitative performance measures to the architect’s program study or create an Owners Project Requirements (OPR) document. For this article, “qualitative performance measures” refer to the metrics that express embodied carbon, but can also include operational energy, water, and even healthy materials.

Integrated Design Process Image An integrated design process (IDP) anchors the architectural program to performance metrics such as carbon dioxide equivalents (CO2e), Energy Use Intensity (EUI), and zero Energy Performance Index (zEPI). So, by completing the IDP, you’re getting the basic tools to optimize embodied carbon and operational energy use in your design:

  1. Target the early phase of the project
  2. Prepare a Carbon Hotspot and Simple Box energy analysis to compare carbon sensitivity of different schemes not limited to wall and roof construction, massing, and solar exposure.
  3. Schedule a workshop with the design team and owner to discuss findings and recommendations.
  4. Establish performance targets such as total Carbon Dioxide equivalents as a basic program requirement.
  5. Choose a compliance pathway and verify design with Life Cycle Analysis and a Whole Building Energy model.

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Building Energy Performance Standards (BEPS) are Coming to D.C., Are You Ready?

In January of this year, the Clean Energy DC Omnibus Amendment Act of 2018 was signed into law, establishing minimum Building Energy Performance Standards (BEPS) for existing buildings. The law requires all private buildings over 50,000 square feet to benchmark energy use and demonstrate energy performance above a median baseline beginning January 1, 2021. If a building does not score above the median performance, it has five years to demonstrate improvement or face financial penalties.

While quite a few of the details on enforcement are still being worked out, the median scores will be based on 2019 building performance and there are actions you can take today to get ready for BEPS.

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Climate Week NYC: Seven Days of Climate Action and Discussion

 

Climate Week logoLast week, as I was writing this blog, I came across a New York Times article: “The Amazon, Siberia, Indonesia: a World of Fire.” By now, I’m sure most of us are aware that the Amazon Rainforest has been burning for weeks, but this deliberate act of environmental destruction will contribute to a feedback loop. These fires release carbon dioxide and kill the trees and species that not only remove greenhouse gasses from the air but are part of vital fragile ecosystems. As more climate-warming gasses fill the air, extreme weather patterns, drought, species loss, and global warming are exacerbated. These effects then accelerate the spread of infectious disease, global poverty, and human health defects. Overall, climate change and environmental degradation negatively affect both humans and the planet, which makes us less resilient and allows for climate change to accelerate even more aggressively. And the cycle continues.

So, for the sake of our (really wonderful) natural planet, and humankind, it is crucial that we try to hinder this feedback loop and make climate action a priority around the world. And, although individually we can try to have a more reciprocal relationship with the planet, our actions and voices carry more weight collectively, which is where Climate Week NYC comes in.

What is Climate Week NYC?

Organized by The Climate Group, Climate Week NYC is an annual week-long gathering for citizens and global leaders to join forces and take action to mitigate environmental harm caused by human activity. There will be a number of public events each day from September 23-29, including tours, film screenings, conferences, and more.

Fun fact: Swedish teenager and activist Greta Thunberg sailed across the Atlantic all the way from England to meet with UN Secretary-General Antonio Guterres, and to attend the United Nations Climate Action Summit, scheduled on the first day of Climate Week NYC!

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What the Climate Mobilization Act Means for Developers, Designers, and Construction Teams

Image of central park and New York City buildigns

The construction industry has been increasingly focused on meeting ever-tightening codes and achieving higher ratings in sustainability certification programs (e.g., LEED, Passive House, etc.). These standards do a good job of raising the bar, but there is a new bar in town and we’re not talking about whiskey.

Local Law 97

NYC’s Local Law 97 of 2019 establishes carbon emissions limits for buildings 25,000 square feet and larger. These emissions limits, which are based on current building performance data, will begin in 2024 and will rachet down in 2030 and beyond. While we continue to work with building owners and portfolio managers of existing buildings (“What Does the Climate Mobilization Act Mean for Building Owners?”), we need to make sure that new buildings and major renovations are set up for success. Developers, designers, and construction teams must take LL97 into account during design, construction and turnover to protect the value of these new assets.

A developer or asset manager’s least favorite word is probably uncertainty, and now there’s a whole new host of uncertainties to think about:

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Five Steps to Get Started with Net Zero Energy Buildings

Net zero buildings are becoming increasingly popular, and some jurisdictions, such as Washington, DC, are projected to become code within the decade. Massachusetts will also begin development of a net zero building code. Curious if your building is a net zero contender or what it would take to reach net zero targets?

What Does it Mean to be Net Zero?

The term “net zero” commonly refers to zero-energy buildings. In simple terms, a zero-energy building is one that produces as much energy as it consumes on an annual basis. There can be nuances and caveats to this definition, but for now, we want to bring you up to speed on five key net zero energy strategies to consider if you’re interested in developing a net zero building.

1. Maximize space for on-site renewable energy.

How tall is your building?

  • Any building over five stories will be challenging, if not impossible, to achieve net zero with on-site renewable energy production alone because building energy demand will likely exceed available site area. Maximize your solar with a smart layout and consider if other renewables, such as geothermal, are possible.

    Image of roof layout

    Typical roof layout for multifamily building, including necessary setbacks for fire access, mechanical equipment access, and shading from bulkheads. Fire access is based on FDNY guidelines.

Do you have other spaces available for solar photovoltaics (PV)?

  • Your development may have a separate parking garage or parking lot on site. These are great places to install a PV system, which can significantly increase the amount of on-site renewable energy production and help make achieving net zero more of a reality.

Do I have to have all renewables on-site to be net zero?

  • If you don’t have enough room for on-site renewables, you can look into purchasing off-site renewable energy options, such as community solar, power purchase agreements, or renewable energy credits.

Now that you’ve considered renewables, let’s move on to net zero building design considerations.

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20 Years of Wintergreen!

A lot has happened since the start of the WinterGreen newsletter, which was first distributed 20 years ago via fax machine. From the inception of LEED, to the Climate Mobilization Act, WinterGreen has covered it all.

In honor of its anniversary, we are looking back at the milestones that occurred along the way and making predictions for the future…WinterGreen Banner circa 1999

1999 – Steven Winter Becomes Chairman of the US Green Building Council

Image of Steven Winter as USGBC ChairmanAs Chairman of the U.S. Green Building Council from 1999 to 2003, Steven Winter helped guide the organization through a period of immense growth. This included the launch of Leadership in Energy and Environmental Design, also known as the LEED® Rating System, and Greenbuild, the nation’s largest green building conference and expo.

 

2000 – SWA Receives NYSERDA Pioneer Award

Image of Steven Winter with NYSERDA AwardAt a gala event celebrating the 25th anniversary of the New York State Energy Research and Development Authority (NYSERDA), Steven Winter Associates (SWA) was presented with the NYSERDA Pioneer Award for their extensive contributions to making buildings more energy efficient and sustainable.

 

2001 – Green Building Guidelines Book Published for Home Builders

Image of Green Building Guidelines bookIn conjunction with the U.S. Department of Energy (DOE), the National Renewable Energy Lab (NREL), and the Sustainable Buildings Industry Council (SBIC), SWA staff collaborated to create “Green Building Guidelines: Meeting the Demand for Low-Energy, Resource-Efficient Homes.” The book provided green building techniques and strategies for home builders and residential construction professionals.

 

2002 – SWA Helps DEC Become New York State’s First Ever LEED Certified Building

Image of New York DEC Headquarters in AlbanyWorking with NYSERDA, Picotte Companies and WCGS Architects, SWA provided certification support to the design team, earning the project LEED V2.0 Silver. SWA’s services included initial LEED tabulations and goal setting, detailed LEED V2.0 evaluation reporting, and completion of the final documentation package, which led to the certification of New York State’s first ever LEED building.

 

2003 – The Solaire Declared Nation’s First “Green” Residential High-rise

Image of The SolaireNew York Governor George Pataki dedicated The Solaire as the country’s first “green” residential high-rise building, calling it “a benchmark for urban sustainable development and for green buildings worldwide.” SWA supported the design team on this project from conceptual design phase through construction administration. The Solaire, located in New York’s Battery Park City, was the first residential building to be completed in downtown Manhattan after the terrorist attacks of September 2001, and was the first beneficiary of Governor Pataki’s green building tax credit.

 

2004 – SWA Joins Project Team for Oculus Terminal at World Trade Center

Image of World Trade Center PATH TerminalLed by the joint venture of DMJM+Harris and STV, as well as the internationally renowned architect, Santiago Calatrava, SWA was invited to join the project team to provide energy efficiency and sustainable design consulting services for the new World Trade Center station, also known as the the Oculus. The rebuilt PATH terminal is incorporated into the design.

 

2005 – USGBC Announces LEED for Homes Pilot Program

Image of home under constructionExcited to announce the first ever LEED program for residential construction, the USGBC immediately began seeking applicants to test the effectiveness of the all new LEED for Homes through a Pilot Program. LEED for Homes, which is considered a green building milestone, was made possible by a passionate committee of industry professionals co-chaired by Steven Winter.

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What Does NYC’s Climate Mobilization Act Mean for Building Owners?

Image of Existing Buildings in NYC

On April 18th, Introduction 1253-2018 was approved by the New York City Council along with several other major pieces of legislation as part of a Climate Mobilization Act. The Urban Green Council describes it as “arguably the most disruptive in our lifetime of the NYC real estate industry.” We agree. While it will take some time to more precisely gauge impact across the industry, here is an initial primer.

Update: On May 18th Intro 1253 was passed into law as Local Law 97 of 2019.

Context

Previous building energy legislation in NYC has focused primarily on providing the market with access to information in the form of benchmarking and audits. In response to increasing demands for more urgent climate action, this new local law will actually require energy performance levels – and significant retrofits in some cases – in most existing buildings over 25,000 square feet between now and 2030 and deeper reductions beyond 2030.

How Does Local Law 97 Work?

The law establishes targets for carbon-emissions intensity per square foot for buildings based on occupancy class. For instance, multifamily buildings, office buildings, schools, and storage facilities will have different intensity targets. Mixed-use buildings will have their targets set based on a weighted average of their different spaces. Across all segments, these targets will get ratcheted down over time. Building on the type of data submitted as part of annual benchmarking, all tenant and owner energy used at a particular building will be converted to carbon intensity per square foot.

Starting in 2024, buildings will be fined on an annual basis for carbon footprint that exceeds their targets. Based on their performance today, approximately 20% of buildings exceed the 2024 – 2029 targets while approximately 75% of buildings exceed the 2030 – 2034 targets, according to the City Council’s press release. As an alternative to this performance-based framework, rent regulated multifamily buildings with at least one rent stabilized apartment will be required to implement a prescriptive list of upgrades by 2024. These upgrades include indoor temperature sensors providing feedback to boilers and apartment thermostatic controls.

What Will It Mean to the Market?

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Buildings to Cool the Climate

The Intergovernmental Panel on Climate Change (IPCC), viewed as the most credible source of climate change research, issued an alarming report on October 2018 removing all doubt – absent aggressive action the atmosphere will warm up by as much as 2.7 ° F above preindustrial levels by 2040, inundating coastlines and intensifying droughts and poverty. The significance of this report is that the effects of climate change will occur in our lifetime.

The building construction sector has a critical role in drawing down carbon emissions by 2040. As nations all over the globe tackle operational emissions from buildings, we must now address our total emissions impact.

Estimated cumulative carbon emissions from new buildings 2020 to 2070

Life-cycle emissions resulting from buildings consist of two components: operational and embodied. A great deal of effort has been put into reducing the former as it is assumed to be higher than the latter. Studies have revealed the growing significance of embodied emissions in buildings, but its importance is often underestimated in energy efficiency decisions.

According to the Embodied Carbon Review 2018 by Bionova Inc, embodied carbon is the total impact of all the greenhouse gases emitted by the construction and materials of our built environment. Furthermore, during their life-cycle, the same products also cause carbon impacts when maintained, repaired, or disposed of.

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What is the Carbon Footprint of Your Holiday Shopping?

Have you ever wondered about the carbon footprint of your shopping habits? Is online shopping better for the environment than brick and mortar shopping? There are many studies on the subject and there are myriad factors to consider when answering these questions. To try and make this process a little easier, we have pulled together existing research and have developed a guide to reducing your carbon footprint this holiday season.

Image of Santa gifting coal

One 2013 study by MIT looked at the impact of online vs. in-store shopping for a few items (a t-shirt, a Barbie Doll, and a computer) and concluded that a few key factors can tip the scales in either direction. While this study ignored the impact of the embodied carbon of these items (more on this later), let’s look at the biggest factors that could contribute to your holiday shopping carbon footprint and factor into the store vs. online debate.

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Linkageless Burner Retrofits for Steam Boilers

Going Beyond Carburetor Technology in the NYS Market

Fun Fact #1: Space heating and domestic hot water generation represent two of the greatest energy end uses in New York State.

Fun Fact #2: More than 70 percent of all New York City buildings utilize steam for space heating.

Background

The clear majority of the distribution systems in these NYC buildings are supplied by high mass steam boiler plants. Digging down a bit further, it is important to note that the most common air:fuel control for these boilers is a mechanical linkage that connects a single servo motor to both the combustion air damper and the fuel control valve(s). We know that adjusting one part of the linkage’s movement affects fuel and air rates elsewhere in the range, making accurate adjustment difficult. We also know that modern linkageless controls use separate servo motors to operate the fuel control valves, combustion air damper, and (in some cases) the flue damper, allowing for finer control.

mechanical linkage system and linkageless system

In fact, SWA recently completed a demonstration study (partially funded through NYSERDA’s Advanced Building Program) to evaluate linkageless burner retrofits on two buildings with respect to energy savings and carbon reductions, as well as qualitative or non-energy benefits. The retrofit materials were funded by Preferred Utilities Manufacturing Corp. of Danbury, CT, who also provided manufacturer’s technical support. The study also focused on quantifying the seasonal efficiency of intermediate-sized, high mass steam boiler plants, which had not previously been studied. The demonstration addresses this gap in the industry’s knowledge.

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Electrify Everything? Part 1

So in utility and policy circles, electrification is all the rage. Grid electricity is getting cleaner (i.e. resulting in lower CO2 emissions), on-site renewables are taking off (sometimes even with storage), and heat pump technologies are getting better. More regional and utility initiatives are encouraging building owners/designers/developers to forego onsite fossil fuels entirely (or at least mostly) to help meet CO2 emission reduction goals. But is electricity really more sustainable than natural gas? Is it cheaper? Which is better, really?

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Low-Carbon Concrete: Reducing the Embodied Energy of a Notorious Emitter

It is safe to say we are in a climate crisis. Of the last 17 years, 16 have been the hottest on record.[1] Sea level is expected to rise by as much as eight feet by the end of the century.[2] And by 2050, as many as 140 million people will have been displaced by climate change.[3] The time to act is now, and a major area of impact is buildings, which account for 40% of carbon emissions in the United States. Better envelopes, lighting, and mechanical systems are helping buildings become more efficient, which means an increasing proportion of carbon—up to 68% of a building’s lifetime emissions—is locked up in materials.[4] This “embodied” carbon gets released during a material’s extraction, manufacture, transport, maintenance, and, eventually, disposal.

If our industry is to meet the 2030 Challenge of carbon neutrality by the close of the decade, we will need to reevaluate building materials and select low-carbon alternatives.

Embodied carbon life-cycle

Figure 1: Courtesy of Faithful+Gould

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Five Year Solar Performance on Connecticut Home

Written by Gayathri Vijayakumar, VP – Senior Building Systems Engineer

Over the last 10 years, we’ve seen great strides in the solar PV market in the United States. Between the federal tax credit and utility-sponsored incentives, the price to install PV systems came within reach of many homeowners. For others, eager to make a positive impact on the environment, power purchase agreements with solar companies and no up-front costs made it possible to utilize their roofs to generate electricity.

While the calculated cost-effectiveness of solar panels relies on the future price of electricity (which we can’t predict), we can confirm that they do deliver energy. In a very scientific study of exactly one home, owned by a SWA engineer, five years of generation data is available. Sure, it’s not the pretty Tesla roof, but these panels were installed back in November 2011. At 4.14 kW, with no shading and great Southern exposure, the panels were estimated to generate 5,400 kWh/year of electricity in New Haven, Connecticut (Climate Zone 5). The panels have exceeded expectations, generating on average, 6,200 kWh/year, which is roughly 70-80% of the electricity required by the 2,500 ft2 gas-heated home and its 4 occupants.

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