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.

Read more

The Value of Commissioning

Written by Jenny Powell, Energy Engineer

What is Commissioning?

Many energy and sustainability programs, standards, and codes require commissioning, including LEED, ASHRAE 90.1, NGBS, IECC, IGCC, the PSEG and NYSERDA’s commercial performance-based incentive programs (see glossary below). As states embrace these codes and enforce commissioning requirements you may ask yourself: what is commissioning and why is it beneficial?

Commissioning agents provide third-party quality assurance throughout the construction process. They review design drawings and submittals, periodically inspect construction progress, witness functional performance testing of mechanical equipment, and ensure that the building staff is trained and ready to operate the equipment after it’s turned over. Commissioning agents work on behalf of the owner to ensure that the owner’s project requirements are met. Most importantly, commissioning improves construction quality and reduces maintenance and energy costs.

The benefits of commissioning are never more apparent than during a retro-commissioning project. While commissioning involves a third-party review of operation during the construction process, retro-commissioning is a third-party review of operations well after construction is complete. Some difficult retro-commissioning projects have shown us how valuable it is to resolve issues when the design intent is still clear (or clearer) – and while the construction team is still onsite!

Read more

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.

Read more

High Performance Walls

Written by Joanna Grab, Senior Sustainability Consultant

Groggy and sleepy-eyed, I swung my feet out of bed this morning. Still waking up, I began the trek to my coffee pot, but was thrown off track when my bare feet stumbled (literally) upon a freezing patch of floor beside the door to my balcony. Suddenly wide-eyed, I ducked into the bathroom to rub my toes against my fuzzy bath mat. Outside, the city seemed to have surrendered itself to a single shade of gray, and though my feet were warming, I could feel the monochromatic January cold pressing its way through the metal window. I put on my architect’s (hard) hat and thought, “these are textbook examples of thermal bridging.” But aside from a chill or a draft here and there what’s the big deal? Well, let me provide a little insight.

Thermal bridging occurs when heat is lost through a less-insulated or more-conductive portion of a building’s exterior. On a frigid winter day, this means heat is lost where insulation is lacking, such as through a metal window frame or the floor slab in my apartment building. Ultimately, thermal bridging results in a less comfortable home that is more expensive to heat and cool.

Another hidden concern is condensation, which can be a consequence of thermal bridging. When warm air comes into contact with a cold spot on the floor or wall, water vapor in the air cools and collects as droplets on the colder surface. This can result in durability problems, as well as poor indoor air quality.

Read more

Tech Notes – Drinking Fountain Height

Where the 2010 ADA Standards apply, 100% of drinking fountains must comply with criteria for accessible drinking fountains found at Section 602. Of those, 50% must have spout outlets located 36 inches maximum AFF to provide access for individuals in wheelchairs (ADA Section 602.4). The remaining 50% must have spout outlets between 38 and 43 inches AFF to provide access for standing persons (ADA Section 602.7). A Hi-Lo drinking fountain satisfies requirements for both standing (Hi) and seated (Lo) persons.

Where there are an odd number of drinking fountains, the odd numbered drinking fountain is permitted to comply with criteria for seated or standing persons. For example, if there are a total of 9 drinking fountains; 4 can comply with criteria for seated persons, 4 can comply with criteria for standing persons, and the 9th one can comply with criteria for either seated or standing persons. As always, be sure to check local code requirements that apply in addition to the 2010 ADA Standards.