Posts

Transformers: Problems in Disguise

Sometimes a significant source of energy inefficiency in a building can be hiding in a place difficult to detect. In some buildings, a single transformer can have a substantial impact on electrical consumption.

Image of currents flowing through a transformer

click to enlarge

Some Background

Transformers are responsible for stepping the incoming voltage to a building up or down depending on the design, intended use, or connected equipment.  A standard electrical socket in a US home or office will deliver 110-120 volts AC. Some appliances require 240 V instead. Large mechanical equipment, such as the air handling units, distribution pumps and chillers found in commercial or multifamily buildings may require 460 V. In buildings where the incoming voltage from the utility does not match the voltage required by connected equipment, a transformer is used to deliver the necessary voltage.  The voltage entering the transformer is called the primary voltage and the voltage delivered by the transformer to the facility’s equipment is called the secondary voltage.

Read more

Technically Speaking: Not All Insulation is Graded Equally

About a year ago, I worked along with other HERS raters and the North American Insulation Manufacturers Association (NAIMA, a.k.a. Insulation Institute) to conduct a study on the importance of insulation installation quality and grading.

RESNET, the nation’s leading home energy efficiency network and the governing body of the Home Energy Rating System (HERS® Index) established standards for grading insulation installation.

The grading is as follows:

Grade I— the best and nearly perfect install which includes almost no gaps or compression… what some would call “G.O.A.T.”
Grade II—allows for up to 2% of missing insulation (gaps) and up to 10% compression over the insulation surface area… what some would call “mad decent”.
Grade III—insulation gaps exceed 2% and compression exceeds 10%… anything worse and the insulated surface area is considered un-insulated.

RESNET Insulation Diagram

Source: RESNET Mortgage Industry National HERS Standards

Read more

Why the Whole Building Approach Matters

At Steven Winter Associates, Inc., we support the whole building approach to design and construction by doing our best to ensure that projects meet sustainability, energy efficiency, and accessibility requirements, among other design strategies and goals. From our perspective, accessibility compliance is a key factor in determining whether a project is truly sustainable and efficient.

The Whole Building Approach to Design (from the Whole Building Design Guide, “Design Objectives”)

As an example, I was recently contacted by a New York City-based housing developer. They received a letter from an attorney stating that three of their recently constructed projects in New York City were “tested” and found to be noncompliant with the accessible design and construction requirements of the Fair Housing Amendments Act and the New York City Building Code. SWA toured the buildings and confirmed that the allegations were in fact true. We identified issues such as excessive cross slopes along the concrete entrance walk, the presence of steps between dwelling units and their associated terraces, the lack of properly sized kitchens and bathrooms, the lack of compliant clear width provided by all user passage doors, etc. It quickly became apparent to us and to the developer that the cost of the remediation required to bring the projects into full compliance would be astronomical.

Read more

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

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