William Maclay - Vermont Architects and Planners
Choices in Sustainability
Wind NRG Partners, LLC Phase 1 - Project Details
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PROJECT DESCRIPTION


Wind NRG Partners, LLC
Manufacturing Facility

Type: Office and Manufacturing Facility
Size: Building total: 46,500 S.F.
Building Footprint: 30,595 S.F.
Site: 9.51 Acres
Program:6,500 SF of Offices, 22,500 SF of Warehouse / Tower / Electronics Production, 6,000 SF of Common Areas, 11,500 SF of Mechanical / Storage / Support
Location: Hinesburg, VT
Completion date: June, 2004
Construction costs: Building: $ 5,440,000
Total project: $ 7,833,000
LEED and Renewable Energy features cost: $ 642,730 ($13.81 / SF - 8.21% of total cost)
LEED Rating: Gold level certification - March 2005

Efficiency Vermont provided $50,000 in incentives for energy efficiency features, including low lighting power density (0.83 watts/sq.ft., average, from lighting design and high efficiency lighting fixtures, occupancy and daylighting controls for lighting, high efficiency cooling and heating equipment, high efficiency building envelope resulting in lower cooling and heating loads, premium efficiency motors, variable frequency drive control for motors and CO2 sensors to control ventilation volumes. EVT also assisted with air leakage testing of the building.


Project Overview


Project Goals and Program:

  • Design a model workplace combining social and environmental goals.
  • Design a corporate headquarters that embodies clients values, mission and core business.
  • Accommodate company's expected growth (30% per year).
  • Develop a model workplace: healthy, functional, beautiful, and productive.
  • Demonstrate a high performance building that uses primarily renewable energy.Solution: A Natural and Human Centered "Living Building"
  • A "Heart" at the center with cafe/commons/meeting areas for human interaction using certified glu-lam timber frame, wood wainscoting and stone fire place for warmth.
  • Interior "Street" with artwork, stained concrete, and transparent display walls to connect the "heart" to all workspaces.
  • Windows to connect office areas to warehouse/production areas.
  • Openings in walls and roofs to provide abundant daylight air and view for connection to nature and natural light in office, production and warehouse spaces and act like lungs and skin.
  • Pool and exercise areas for employee health and wellness.
  • Art floor by a local artist tells the history of wind energy and assists with way finding throughout office areas.
  • Environmental systems and equipment are on display, and integral to work life.

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Sustainable Design Features:


Sustainable sites

  • Native vegetation/landscape
  • Natural setting, built into hillside, set back from road.
  • Reduced building footprint.
  • Pond for cooling system heat rejection, storm water treatment and aesthetics.
  • Alternative transportation encouraged (bike rack, bike and recreation paths, electric vehicle charging stations, minimal parking)
  • Light pollution reduction from low wattage, cutoff outdoor lighting.
  • Southern orientation.

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Energy


  • Energy costs projected to be about one fifth those of a similar new building built to current code.
  • 67 Kilowatt solar photovoltaic (PV) system for electricity generation of two thirds of annual energy requirements (75,000 kilowatt hours per year).
  • PV system will avoid emission of up to 100,000 pounds of carbon dioxide annually (1.33 lbs. of CO2 per kilowatt hour saved). Wood pellet fuel saves 4000 lbs. CO2 compared to propane.
  • Solar hot water system (6 rooftop collectors) for 80% of annual domestic hot water requirements.
  • Wood-fired radiant floor heating (wood pellet-fired boiler); high efficiency backup propane boiler.
  • Radiant floor (slab) cooling system powered by ground source heat pumps rejecting heat to pond.
  • Networked building automation systems maximize building's efficiency (heating, cooling, ventilation).
  • Windows automated for natural cooling (open and close based on indoor temperature and outside dew point).
  • High efficiency window and skylights for maximum daylighting and solar control.
  • Automatic and manual natural ventilation to minimize air conditioning.
  • High efficiency office equipment upgrades (laptops and Energy Star rated office equipment and appliances).
  • High efficiency lighting with automatic dimming.
  • Occupancy sensors to minimize lighting needs.
  • South-facing windows. All glass in the building has a low SHGC, for reducing cooling loads.
  • CO2 monitoring to reduce unnecessary ventilation in open office areas.
  • White reflective warehouse roof prevents heat gain.
  • Reflective light-guiding European blinds to enhance daylighting.
  • Super insulated, air tight building envelope with minimal thermal breaks.

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Water Efficiency

  • No irrigation.
  • Dual flush toilets and other water-saving devices reduce water consumption by 30% saving 100,000 gallons per year.
  • 2/3 acre (10-ft deep) pond for cooling, ground source heat pumping, storm water and recreation.
  • Pervious parking surface allows rain water to soak in (avoid storm water run-off)Materials and Resource Efficiency
  • More than half of wood used is sustainably harvested Forest Stewardship Council (FSC) certified.
  • Vermont made wood furniture from FSC wood.
  • Stained concrete flooring to minimize resource consumption.
  • Recycled steel structure (from cars, cans, and appliances).
  • Recycled glass bathroom tiles (from car windshields).
  • Wood pellets for heating made from waste sawdust.
  • No chlorofluorocarbons (CFC's)
  • Recycled Post Office boxes in mailroom.
  • Concrete with flyash.
  • Low toxic pressure treated wood.
  • More than 85% of construction site waste recycled.
  • More than 10% of materials have high recycled content.
  • 90% recycled steel structure (cars, cans, and appliances).
  • Kitchen cabinets made with formaldehyde free certified wood and wheatboard interiors.

Indoor Environmental Quality

  • Natural ventilation/operable windows.
  • Daylighting in all workstations.
  • Low or no VOC emitting stains, paints, adhesives, sealants.
  • Formaldehyde-free composite wood.
  • Minimal carpet (elevator only), green label certified.
  • Meets ASHRAE indoor air quality standards.
  • CO2 monitoring for air quality.
  • Heat recovery ventilation.
  • Radiant heat/cooling for comfort.
  • Innovation & Design Process -Collaborative design process with multi-disciplinary team.
  • Drainage plane exterior siding.
  • Design integrates human, envelope, mechanical, structural, and site engineering systems.
  • Human centered design is a major focus.


PROJECT ENERGY AND SYSTEMS

NRG Systems - A Model of Energy Efficiency and Renewable Energy

Through the use of renewable energy, a super-insulated structure, energy efficient windows, lighting and equipment, and smart controls, the NRG building achieves world-class energy performance.

Mechanical Systems

A high efficiency radiant heating and cooling system provides optimal comfort and climate control in the building. Water circulates through eight miles of tubing in the building's concrete floors. In the winter, warm water is circulated through the tubing. In the summer, cool water is circulated. Five high efficiency heat pumps provide chilled water to the radiant floors and the ventilation system for cooling. The heat pumps reject heat from the building through two miles of tubing in the bottom of the heat-sink pond located in front of the building. Total capacity cooling is 30 tons (~720 sq.ft. of cooled floor space per ton) with EER ranging from 13 to 21, depending on pond and system loop temperatures. Cool water from the heat exchanger in the pond can be used directly in the slabs for cooling, when temperatures are appropriate.

Wood waste from lumber milling and other sources is transformed into pellets to provide heating for the building. Two wood-pellet-fired boilers provide primary heating for the building's radiant heating system. A 90+% efficient propane-fired boiler provides back-up heating. A wood pellet silo located in the warehouse holds 30 tons of pellets, enough for one year's worth of heating. The pellets are gravity fed into the boilers located on the floor below. The total design heating load is 400 kBtu/hr (8.6 Btu/sq.ft.-hr).

A networked computer-based control system orchestrates the building's heating, cooling and fresh air ventilation systems. The system is programmed to provide the best comfort at the lowest energy consumption. It also tracks building sub-system energy use to maximize energy efficiency over time. Office spaces include operable windows so employees can have fresh air and natural cooling. Green and red indicators on "nurse's station lights" let employees know when windows may be opened and when the air conditioning is operating. During the summer, Vermont weather is often cool enough to cool the building during the day or to pre-cool the building at night for the next day, avoiding the use of air conditioning and saving a significant amount of energy. Several automatically operated windows open when conditions are right. Two large "barn fans" in the warehouse area supplement this natural air flow when needed.

The ventilation system provides fresh air to all the office working spaces, while removing stale air at the same time to provide superior indoor air quality. An "energy recovery wheel" recovers 75% of the heat and moisture energy required for fresh air in winter and in summer. The boilers add more heat in the winter when it is needed and the heat pumps further cool and dehumidify the air in the summer. Up to 4,200 cfm of outside air is provided. Ventilation air provides the latent portion of the cooling load in summer. The ventilation rate is also automatically boosted to provide additional sensible cooling beyond that provided by the slab, when and where needed. With its large open space and ample windows, the warehouse uses natural ventilation for its fresh air needs.

Every motor from large to small was researched and chosen to minimize power usage and heat gain from equipment. Employees use laptops, which consume only 27 watts, compared to 100 to 150 watts required for a typical desktop computer. The kitchen and other areas feature Energy Star-rated equipment and appliances to further reduce energy consumption. Roll down window shades in workspaces reduce the sunlight's glare and also help prevent heat build up.


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Building Envelope

The building's walls and roof are tight and "super-insulated." An air barrier is located between two 3-inch layers of foam insulation on the roof to reduce air leakage. The roof's overhang is made of OSB-skinned insulated panels to avoid "thermal bridges" caused when steel, passing from inside to outside insulation, carries heat out during cold weather. The warehouse walls consist of 4" thick foam, steel-skinned panels. The office walls have 3" of sprayed-on foam, forming a tightly insulated wall system. Six air leakage tests over the course of construction, combined with infra-red scanning, helped the contractor locate and seal air leakage points. The warehouse's white TPO roof helps reduce summer heat gain, while avoiding the use of vinyl compounds. Building systems were chosen and detailed for long term performance, reducing repair and materials costs over time.

The windows have an R-value of 5, twice current energy code, with triple glass, low solar-gain, low-e layers and argon gas. The edge spacers between the glass act as insulators, and the frames are made of insulated fiberglass. Ground floor slabs are insulated with 4" of high density expanded polystyrene.

Renewable Electricity

The 67 kW solar installation is the largest in Vermont. Twelve 2.2 kilowatt trackers use unique non-electric "thermal motors" (by Zomeworks) to track the sun and improve the collection of solar energy by about 30% compared to fixed solar panels. On the south-facing roof, 35 kW of Unisolar amorphous silicon PVs are adhered directly to the standing seam metal roofing. On the building's south wall, there is an awning comprised of 7 kW of high efficiency crystalline silicon PV panels. Roof-mounted solar thermal collectors use the sun's energy to heat the building's domestic hot water. NRG is going through the permitting process to install a 10-kilowatt wind turbine on the hill behind the building.

Daylighting and Electric Lighting

The building's southern orientation and numerous windows and skylights bathe the warehouse and office areas with natural light. A high strip of south-facing windows in the offices is equipped with special "light guiding" blinds to redirect sunlight up onto the ceiling and diffuse the light for general illumination. Open floor plan and glass in interior partitions further distributes light. Skylights in the second floor offices supplement and balance of light coming from the windows. Direct sun from the skylights is diffused by the white north walls most of the year, and the floor of the corridor area during the peak of summer.

High efficiency Super-T8 fluorescent fixtures are used throughout for general ambient illumination. General lighting in the offices directs most of the light toward the ceiling to mix the electric light with the daylighting coming in through the windows. Automatic dimming ballasts dim or brighten the lights as sunlight increases or decreases.

In the warehouse, skylights and large windows practically eliminate the need for artificial lighting on sunny days. The triple-glazed acrylic skylights include two prismatic layers that diffuse the light. Three-lamp dimming fixtures direct most of the light downward, for higher efficiency. Occupancy sensors in every room of the building, except closets and mechanical rooms, turn lights off when they are not needed. Fluorescent parking lot lighting is also controlled with occupancy sensors.