31 Tannery Project

Utility Metering
The utility company’s gas and electric meters have pulse output signals monitored by the building's DDC system, providing a visualization tool and important feedback. For the electric meter, as the building’s photovoltaic array output approaches the building load, the pulse meter slows and then stops. During these periods, additional meters are needed to determine building load and the amount of surplus electric energy sent to the grid.

Solar Thermal Hot Water
In addition to the solar photovoltaic system that provides electricity for the building, a solar thermal system provides hot water for domestic use (showers, kitchen and bathrooms). Two 80 gallon preheat tanks serve an 80 gallon backup electric hot water heater via a double wall heat exchanger in the closed loop solar system.

The solar thermal system eliminates the need for fossil fuels by heating water for sinks, showers and the dishwasher. Two preheat tanks store hot water during night hours and on cloudy/rainy days. Cold water is preheated by a 160 ft2 rooftop closed-loop solar hot water system from approximately 50°F to 150°F-160°F and regulated by a safety/tempering valve to 120°F. A solar thermal system was selected to heat the domestic water because it is more efficient than a solar photovoltaic system in providing hot water.

However, because 31 Tannery Project is grid-tied and produces surplus electricity that can be shared, an electric, rather than gas, water heater was chosen as the backup system for cloudy days and night use.

A commercial size radiant heating system serves a 26,190 ft2 shop and 15,318 ft2 two-story office. Approximately nine miles of in-slab PEX tubing and 16 manifold headers serve 146 loops with 80 radiant zones. During installation, 18 slab sensors were embedded in the concrete throughout the building. The loop service areas are divided into RTU-1 variable air volume (VAV) hot water- coils, radiant-first-floor, radiant-second-floor and shop-radiant areas. Generally, the boiler plant operates in full condensing mode with maximum efficiency. The majority of the time the water in the radiant flooring is 80°F.

During the coldest winter days, the highest temperature in the radiant loop is 100°F. Because human body temperature is 98°F, visitors to the building often are surprised that the floor seems cool to the touch. Visitors are satisfied after placing one hand through the garage bay doors on the exterior parking surface and the other on the radiant heated slab. The visualization of the embedded sensors and thermal imaging from the infrared camera also intrigues visitors. In the boiler room, a 14,000 Btu/h gas-fired, low nitrogen-oxide, full modulation condensing boiler serves four main loops. The hot water loops are provided with variable speed and temperature controls. Loop service is divided into VAV hot-water-coil and radiant-first-floor, radiant-second-floor, and shop-radiant areas. The room also includes a wall mounted, foldout workstation with network connections and the main control panels for the DDC system. Provisions have been made for future connections to a ground-mounted solar thermal heating plant.

Rooftop Units
High-efficiency U.S. Environmental Protection Agency (EPA) ENERGY STAR® HVAC systems heat, cool and ventilate the building. RTU-1 serves the office wing, RTU-2 serves the shop offices, and MUA-1 serves the main shop. The two rooftop unitsare equipped with factory-installed controllers. RTU-1 is a 50 ton VAV system with premium efficiency motors, enthalpy economizer,and embedded network controls that serve the two-story office area. RTU-2 is a 7.5 ton constantvolume system for the shop office and is equipped with high-efficiency motors, an enthalpy economizer and embedded network controls.

Future Plans
The 31 Tannery Project received a 100 ENERGY STAR score and was cited by New Jersey Governor Jon Corzine as being the first business in that state to meet his Executive Order 54 for the reduction of greenhouse gases. The company reduced its carbon footprint 83%. With a payback of five to seven years, the building proves that building green and designing for sustainability is commercially viable.

The Ferreira team is not stopping here. They are working on a plan to implement a solar thermal system to heat the radiant flooring system and eliminate the building's carbon footprint. This was not included in the original design because of cost. Current solar and high-efficiency systems added 35% to cost, and the owner required a short payback. Additional projects are underway.

Ferreira is working with the State of New Jersey, Liberty Science Center, and Newark Public Schools to implement a renewable energy learning program to be taught from grade school through high school.

The Ferreira team also hosts visitors on a regular basis to let other businesses learn how they can apply the same techniques to their building and achieve similar results. Upon visiting 31 Tannery Project, many business owners have expressed interest in investing in renewable energy and energy efficiency for their buildings.

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