Power vs. Energy

I can get worked up about units, and this can really annoy people. It especially annoyed students I taught in grad school. I was pretty tyrannical when grading; they always had to include units in their calculations. They could have all the right numbers, but they didn’t get full credit unless all the units were right too. I have no regrets about being such a stickler, because I see tons of confusion about this in the building & energy fields. So here’s a rant about one of my pet peeves: power and energy.

Question: What’s the difference between Power and Energy?

Is this some kind of philosophical question? A koan to meditate upon? No. There’s a real answer (in the engineering world at least). Power is the rate of energy.

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Replacing Indian Point

Written by Mike Flatley, Director, Commercial Building Energy Services

Under an agreement reached earlier this year between New York state officials and Entergy, the Indian Point Energy Center could be shut down as early as April 2021. The big question going forward is what will replace the 2,000 MW of electricity currently being provided to the downstate region by Indian Point. This energy gap will occur just as New York State is working to meet Governor Cuomo’s goal of having renewable energy account for half of the electricity delivered by utilities in New York by 2030.
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2016 New York Energy Code Blower Door Testing – How Does it Measure Up?

Written by Sunitha Sarveswaran, Energy Engineer

Welcome to part three of the air sealing blog post series! In previous posts, we have reviewed the substantive changes in 2016 New York Residential and Commercial Energy Code, focusing specifically on the new blower door testing requirements. In this blog post, we’ll examine how these requirements stack up in comparison to green building certifications that we are already familiar with: LEED for Homes, LEED BD+C, ENERGY STAR® Certified Homes, ENERGY STAR® Multifamily High-Rise (ES MFHR) and Passive House (PH).

To make this easier to digest, we’ve divided this comparison into two parts – compartmentalization and building envelope. If you need a refresher on the difference between these two types of blower door tests, we recommend referring to the article “Testing Air Leakage in Multifamily Buildings” by SWA alumnus Sean Maxwell.

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Heat Pumps Are Taking Over

Air-source heat pumps are a booming business. In the Northeast, manufacturers report that sales of residential systems have increased by 25-35% per year over the past 5-10 years. We’ve seen more and more systems being installed in existing homes (to provide cooling while offsetting oil or propane used for heating) and into new homes (often as the sole source of heating and cooling).

We’ve looked into these systems often, and from many perspectives. I’m planning a series of posts, but, for now, here are the answers to some basic questions we receive from clients.

First, the basics: What is an air-source heat pump (ASHP)?

It’s an air conditioner that can operate in reverse. During the summer, it moves heat from indoors to outdoors. In the winter, it moves heat from outdoors to indoors. We helped NEEP (the Northeast Energy Efficiency Partnerships) to put together a market assessment and strategy report on ASHPs. The early sections in this document (see p. 12) outline the different terms and types of heat pumps (ducted/ductless, split/packaged, mini-split, multi-split, central, etc.) Unfortunately, different people can use the same term to mean different things, but hopefully the NEEP Northeast/Mid-Atlantic Air-Source Heat Pump Strategies Report can help clarify things.

Indoor section of heat pump.


Outdoor section of a heat pump.

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California: Three Hours Behind the East Coast, but Years Ahead in Sustainability?!

Solar Panels San Francisco

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As a native Californian, I often marvel at my home state’s progressive attitude towards environmental conservation. In 1988, we were the first state to adopt air quality standards, which the federal Clean Air Act would later be amended to resemble. More recently, landmark legislation such as A.B. 32, or California’s Global Warming Solutions Act of 2006, set the first statewide requirements for GHG emissions reductions in the country. Today, cities like San Francisco have plastic bag bans and zero-waste initiatives. However, our culture is one of sustainability partly out of necessity—in January 2014, Governor Brown declared California’s severe and sustained drought situation a state of emergency. Despite our already resource-constrained present, California’s population is anticipated to increase by 14% over the next fifteen years to 44 million people. The good news is, we’ve made some big strides recently in planning for the future demands of an ever-growing population.

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