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Maria is a Mechanical Engineer specializing in energy efficiency for high-rise commercial buildings. Her ability to perform energy and economic analysis helps provide building owners with the tools they need to ensure compliance with current incentive programs and green building certifications.

Posts by Maria Rode

Recent Developments in Off-Shore Wind Energy Production and Renewable Energy Storage

Image of off shore windmills

Block Island Wind Farm, courtesy of the US Department of Energy[1]

Overview

There have been several local and global developments recently with regards to off-shore wind turbines. Advancements in energy storage from both wind and solar energy, coupled with the increased rate of adoption of wind turbines could serve as a major step towards a more renewable-based energy grid and a more sustainable future.

Updates on Energy Production

First, let’s explore some recent news surrounding the adoption of off-shore wind turbines. On a global scale, Scotland’s Hywind project recently proved that technology developed for and by the oil drilling industry can be successfully applied to off-shore wind turbines.[2] The floating 30 MW wind farm, made up of five turbines off the Aberdeenshire coast, has been operational since October 2017. During a three-month period of stormy conditions from November 2018 to January 2019, the wind farm managed to continue energy production at 65% of their maximum capacity. Note that during this period, a North Atlantic hurricane produced swells up to 27 feet! Over the course of a year  “maximum capacity” is approximately 135 GWh of electricity- or enough to power 20,000 Scottish homes. To ensure that the turbines can withstand weather events on that scale, the floating turbines are ballasted by 5,000 tons of iron ore, and 1,323 tons of chain anchor it to the seafloor. This off-shore farm proves that wind turbines can be successfully deployed in deeper waters where it would be increasingly expensive to extend the physical structure of the turbine tower to the seafloor. Additionally, the US, UK, Ireland, Portugal, Spain, France, and South Korea all have started to piggyback off the success of the Hywind farm in various ways. For instance, South Korea partnered with the Equinor, the primary backer of Hywind, to conduct a feasibility study for a 200 MW farm that would be located off the coast of Ulsan.[3][4][5][6]

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The Impact of Energy Star’s Portfolio Manager August 2018 Updates on NYC’s Local Law 33 Grades

Image of Letter Grades from SmartBuildings.NYC site

Letter grades are coming!

NYC’s building owners and real estate management firms now have one more thing on their plate to consider: Local Law 33 of 2018. LL33 compliance will assign letter grades to buildings required to benchmark energy and water consumption. The energy efficiency score will relate to the Energy Star Rating earned using the U.S. EPA Energy Star Portfolio Manager (PM).

The law will come into effect on January 1, 2020, and will utilize the previous year energy data to set the energy efficiency score and letter grade as follows:

Picture of Buildings, with quote "Your energy letter grade will be posted in your lobby in 2020. Are you ready?"A – score is equal to or greater than 85;

B – score is equal to or greater than 70 but less than 85;

C – score is equal to or greater than 55 but less than 70;

D – score is less than 55;

F – for buildings that fail to submit required benchmarking information;

N – for buildings exempted from benchmarking or not covered by the Energy Star program.

Why is my letter grade lower than expected?

Property owners should be made aware that if their property earned an energy efficiency score of 75 for the 2018 Benchmarking filing, the new score for the 2019 benchmarking filing may have fallen as much as 20 points. In LL33 terms, what could have been a letter grade “B” could now be “C” or “D” based on PM updates implemented in August 2018. Property owners will want to learn how the Energy Star PM update will affect their LL33 letter grade.

To understand the correlation and impact that the August 26, 2018 Energy Star PM update will have, it is important to look back at what took place as part of that update.

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Replacing Indian Point – An Update

Last year, we wrote about New York State’s plans for replacing the 2,000 megawatts of electricity provided by Indian Point. As of March 2018, Indian Point is still slated to close in April of 2021. The New York State Independent System Operator (NYISO) will reassess the plant’s retirement plan later this year and will continue reassessing this plan regularly to ensure that the state’s electricity needs are met. At the time of the initial closure announcement, the replacement plan leaned heavily on increasing transmission capacity to New York City, particularly via the proposed Champlain Hudson Power Express. However, there were still some gaps between downstate’s power requirements and the total power available without Indian Point.

Indian Point Image

In December 2017, NYISO released an Indian Point retirement assessment report and concluded that downstate’s power requirements will be met, providing that three proposed power plant projects in New York and New Jersey are completed on time. The CPV Valley Energy Center will be a 680 MW natural gas-fueled combined cycle plant in Wawayanda, NY, opening later this year. The Cricket Valley Energy Center will be a 1,100 MW natural gas-fueled power plant in Dover, NY, and is slated to begin power generation in 2020. An additional 120 MW of capacity will be added in Bayonne, NJ. As of the end of 2017, NYISO has determined that all three of these projects must come online by 2021 in order for the Indian Point shutdown to go through.

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Recovering from Heat Recovery Woes

IECC Image

The International Energy Conservation Code (IECC) has a number of requirements involving energy recovery on ventilation systems. Requirements vary based on climate zone, building type and size, equipment capacity, and equipment operating hours. As a result, many new construction projects must now incorporate energy recovery considerations into their design.

An energy recovery unit (ERU) equipped with a heat wheel can be a great way to satisfy these energy recovery requirements. The ERU can be a roof-mounted air handling unit, or can be an air handling unit located inside a mechanical room with outdoor air and exhaust streams ducted in. The heat wheel is positioned so that half of the wheel sits in the exhaust air duct and the other half sits in the outdoor air intake duct. During cold weather, the wheel spins, transferring heat from the exhaust stream to the outdoor air intake stream. During hot weather, the wheel transfers heat from the outdoor air intake stream to the exhaust stream. In both cases the heat exchange enables the building to take advantage of the more comfortable conditions of the exhaust air, while still allowing fresh air to enter the building. During extreme weather conditions, heat wheels can save energy on space conditioning while still allowing for healthy indoor air quality.

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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.

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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. (more…)