NRG Systems Energy Saving System – LEED Gold Certified in Industrial Building Construction.
Joy Null, Director of Public Relations, Watt Stopper/Legrand
June 2007, Santa Clara (USA, California). NRG Systems, headquartered in Vermont, built its new headquarters taking into account environmental requirements, as well as requirements put forward by local unions and employees. The 4,325 square meter space includes offices, workshops and warehouses. The company, which produces meteorological equipment, is located here. The main criteria for the construction of the building were: reducing the harmful environmental impact on the environment and improving the energy-saving indicators of the building.
As already mentioned, one of the project goals was to minimize energy needs in all areas of building operation, including heating, air conditioning and lighting. The second goal of the project is to provide energy needs (as much as possible) from renewable energy sources. The owners of the construction companies are confident that the investments made can guarantee significant long-term savings.
Naomi Miller (Naomi Miller Lighting Design) and Andy Shapiro (Energy Balance) envisioned the building's daylighting concept. Working with Watt Stopper/Legrand, the team selected an energy-saving system that would meet the ambitious design criteria.
Daylighting Systems and Light Control
Careful orientation of the building relative to the cardinal directions and the architectural design features provide natural lighting not only for the office space but also for the warehouse space. Strategically placed windows (including those on the roof) allow daylight to penetrate into the building's farthest areas, creating soft, diffused lighting.
Natural daylight is supplemented by an electrical lighting system consisting primarily of high-efficiency T8 fluorescent lamps with ballast brightness control from Watt Stopper/Legrand, a leading manufacturer of energy-saving lighting control systems for commercial and municipal construction.
Installed photo sensors continuously monitor the level of outdoor natural light, and fluorescent lighting is automatically adjusted to provide optimal lighting levels. The offices have a multi-zone lighting control strategy, providing separate lighting control for each workstation (Figure 1).
An optimal daylighting scheme and adjustable fluorescent lighting provide the required level of illumination for the workstation whenever it is occupied.
Workstation occupancy sensors
Additional energy savings are achieved by using presence sensors at the workplace. Their installation ensures that daylight lamps are switched off when no one is at the workplace, thus preventing any unnecessary waste of energy. To achieve maximum energy saving, most workplaces are additionally equipped with manual switches.
In accordance with the size and functional purpose, each workstation is equipped with passive infrared sensors, ultrasonic sensors and bidirectional sensors. “Dual” technology is used comprehensively in several offices or a large hall.
Using combined technologies ensures the best sensitivity and maximum coverage with zero false alarms. If any two different technologies are used in combination, they must each separately register that the workplace is occupied before the command to turn on the lights is given. If the workplace is abandoned, the lights will remain on until both types of sensors register the absence of the owner.
Special weather-proof sensors are available for outdoor installation.
They can operate in a temperature range from -5°C to +55°C.
Residents of nearby areas also benefit from the use of sensors, since their operation reduces the so-called «light pollution» coming from the windows of houses after dark.
Ballast Control of Lighting System
NRG Systems lighting system is built mainly on the use of high-efficiency T8 lamps, connected via a ballast circuit with programmable electronic control, providing the lamps with maximum light output and long life. Low, normal and high ballast resistance can be used for different parts of the building. This will allow the owner of the workplace to set the desired illumination and save electricity.
Although the idea itself sounds simple, its implementation complicates the work at the design and construction stages. Each type of cable layout requires its own outlet, which confuses suppliers who do not understand the differences between ballast resistances. This will significantly complicate the installation schemes. Also, the contractor should take care of the color differentiation of the different types of wiring in each room.
In ceiling, wall and decorative floor lamps it is supposed to use, first of all, compact fluorescent lamps of 32 watts.
The design restrictions on the type of lamps used significantly simplify further maintenance, and allow the owner to generally save on replacing failed lamps.
System setup
When asked whether the lighting control system currently functions optimally, designers usually answer no. There are several compatibility issues that are not yet satisfactorily resolved, since they require bringing together manufacturers of different types of equipment: lighting wiring, ballast electronics, the luminaires themselves, and the electronic control system. This requirement requires the building owner to be an expert in electronics.
After a series of field measurements, observations of system behavior, and analysis of laboratory test results, Shapiro and Miller discovered that some wiring runs that were designed to use a single ballast for three lamps were actually wired for one lamp and a pair of lamps. As a result, the additional current flowing through two ballasts overloaded the system.
Additionally, the installed lamps were not compatible with the ballast load, so the wiring required rebalancing.
The designers also discovered a bug in the operation of the daylight controller, which is designed to turn off the lights on a bright sunny day. Once Watt Stopper/Legrand engineers learned of this, they were able to recommend recommunicating the controller to correct the bug.
Electricians also had difficulties implementing a system where the lamps could be controlled by an external signal (both daylight sensors and sensors for the presence of a person at the workplace). These difficulties were associated with the complexity of the joint communication «sensor — relay — ballast resistance — switch». Researchers noted that putting the sensors into operation requires a significant amount of time, especially given the desire of the building owners to minimize energy consumption. This requires re-adjustment of such parameters as sensitivity, which, by the way, determines the «live» time of the sensors. However, the extended commissioning period pays for itself. Now the systems work exactly as intended at the design stage.
Successes of the designers
Fig. 2. Approximate annual energy costs of NRG Systems buildings compared to typical buildings
The result of careful attention to detail in the design was a system of relationships that uses one-third less energy than a typical new building. The lighting load for the new project will be only 0.77 watts per square meter, which is 46% lower than the ASHRAE/IESNA 90.1-2001 standard. The savings gained from this control strategy were demonstrated by continuous energy monitoring. During the daytime, energy consumption was reduced by more than 40%, even in the winter months.
The actual energy consumption for lighting the building turned out to be quite close to expectations: 40,000 kWh from March 2005 to February 2006. This building project became one of the few to earn LEED Gold certification.
NRG Systems has also had some success in using cheap energy — 72% of its energy comes from renewable energy sources such as solar, wind and fuel cells.
The company's founders, David and Jan Blittersdorf, set up and paid a premium of 8.21% of the project's $7.833 billion cost for a specialized third-party project, with the photovoltaic system requiring significant investment. According to David, «We've already prepaid most of our energy costs in the hopes of using renewable energy, so we don't have to worry about ever-increasing electricity rates.» He estimates that savings of $4 million to $8 million have already been made in the design phase over the 30-40 years of the building's life. Per year, that translates to about $643,000 in premiums for the building's construction, $460,000 for the renewable energy. The LEED certification premium was $183,000.
Designer Andy Shapiro concludes:
“The daylighting project premium, along with carefully selected energy-efficient light sources and a high-efficiency control system, will offset the low utility bills relatively quickly.”
By implementing the proposed project, NRG Systems reduced all aspects of building energy consumption. For example, the electricity consumption for lighting the premises is one-third of the typical consumption for a new custom-built building (Figure 2).