VRF Systems vs. Electrical Resistance Heaters – A Case Study

Variable refrigerant flow (VRF), also known as variable refrigerant volume, was a concept developed by Daikin Industries in the 1980s. The technology is based on transferring heat through refrigerant lines from an outdoor compressor to multiple indoor fan coil units. VRF systems vary the amount of refrigerant delivered to each indoor unit based on demand, typically through variable speed drives (VFDs) and electronic expansion valves (EEVs). This technology differs from conventional HVAC systems in which airflow is varied based on changes in the thermal load of the space.

The two main VRF systems are heat pump systems that deliver either heating or cooling, or heat recovery systems that can provide simultaneous heating and cooling. These two applications, plus the inverter-driven technology of the outdoor compressors, allow for greater design flexibility and energy savings. In applications where heating and cooling are simultaneously called for in different zones, VRF heat recovery systems allow heat rejected from spaces that are being cooled to be used in spaces where heating is desired. Read more

Which LEED Rating System Do I Use? Part 1: NC versus Midrise

Here’s a question our clients often ask: “I’m building a new residential building, should I use LEED for New Construction (NC) or LEED for Multifamily Midrise?” The answer isn’t exactly simple, especially with the introduction of new credit requirements in LEED v4 and the fact that USGBC allows project teams to choose between the two rating systems. Ultimately, it’s often a difficult decision based on the goals and final design of the project. So, in an effort to help clear up the confusion and possibly make the decision a little easier for you, we decided to break down a few scenarios that highlight key differences between the rating systems that may not be apparent upon first glance. In this first installment, we’ll start with a smaller multifamily building to get a sense of the essential differences between the rating systems and begin to understand the critical decision-making points.

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Moderate Rehabs in Pre-War Buildings: Practical Limits to Hydronic Building Energy Savings

Written by Bryan Simpson, Mechanical Engineer

New York City has established high goals for CO2 reductions as part of the 80 x 50 plan enacted under Mayor de Blasio’s administration. In short, NYC aims to reduce its CO2 production by at least 80% by 2050 (from a 2005 baseline). This requires vast energy conservation and renewable energy production proliferation across the city’s energy, transportation, waste management, and building sectors. Buildings themselves account for 68% of current CO2 production in the City, and as such have the largest reduction targets1. Goals can only be met by implementing repeatable and scalable scopes of work in coordination with policy updates and improvements in other energy sectors. To better understand the efficacy of these moderate improvements on overall energy consumption, we’ve analyzed the results from a recent portfolio rehabilitation. These findings help us to create a map of where we need to go in order to approach 80 X 50.

Figure 1: 80 x 50 NYC Buildings CO2 Reduction Goals, NYC Mayors Office of Sustainability, Roadmap to 80 x 50 Report

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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.

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Green Building Targets the Indoor Environment, as Health Becomes Top Priority

SWA_GreenEnergyTimes

In SWA’s second contribution to Green Energy Timeswe examine the certification programs, operational strategies, and occupant behavior trends that contribute to enhanced indoor air quality (IAQ). The full article is featured below, or on page 29 of the April-June edition of Green Energy Times.


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