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Using Thermal Mass and PCM to Shift Demand Off-Peak: A Paradigm Shift in Cold Storage Design

R. Gary Black, PE Raymond D. Cole, PE (ASHRAE Member)

Cold storage facilities are likely not the first buildings that come to mind when thinking about high performance buildings. However, the number and size of these facilities are growing every year, in part due to a worldwide focus on improving the “cold chain” for perishable food products. For most cold storage facilities in temperate regions peak electricity consumption occurs during product harvest, which occurs in the summer and autumn months during daylight hours when temperatures and electricity prices are the highest. Because it is not feasible to shift cooling loads by changing the harvest operation or schedule, and because of a heightened interest by utilities and regulators in demand side load management, it seems imperative to question the efficacy of the refrigeration industry status quo construction type – the low-mass, insulated metal panel (IMP) building. 

With grant support from the Rural Energy for America Program (REAP), the authors designed and constructed a cold storage facility which uses a unique wall and refrigeration system that together reduce energy use and shift electrical demand to off-peak times of the day . The energy efficient wall employs structural concrete membranes wrapped around an R-100 insulated core. Enhanced thermally with phase change 
material (PCM), the thermal storage capacity of the wall is increased tenfold, theoretically enabling the facility to span a six hour peak-demand period without relying on conventional refrigeration. Load shifting is paramount to the increased reliability and efficiency of the energy grid. To this end, utility companies have implemented peak-pricing models and incentive programs to encourage energy users to shift off-peak. Calculations show that the completed building presented in this paper will reduce energy costs by 50% compared to industry standard, Title 24 construction, resulting in a simple payback for the added investment in less than four years. 
 

Guam Housing

Integrated Structures Inc.

The Work of the Project:  The project is a two-bedroom single family residence with a total plan area of 1003 Square feet. The walls are constructed using a patented and patent pending Energy Mass™ wall system, fabricated from Quadlock, ICF forms, and reinforced concrete (shotcrete) combined with Tropical PCM (phase change materials). This combination provides an innovative new energy reduction product designed for equatorial installations, providing superior energy, wind and earthquake performance.

 

Coupled with the wall system, an innovative mechanical system which uses off the shelf equipment employs radiant cooling coupled with a fan coil for de-humidification. The roof system, based upon the Navy Base and Andersen AFB, Guam approved standard developed by MCR Guam, uses a proven engineered, Cool Roof, aluminum metal panel roof system which is designed and certified for 170 MPH wind speeds, providing superior performance and corrosion resistance and is coated with a specially formulated for Guam, warranted, long lasting paint system.

With the above combinations (insulated exterior walls, phase change materials, radiant mechanical system, and insulated roof) cooling loads will be reduced approximately 75% over the standard construction methods employed for the residential market. 

The following outline specs address information required by the invitation in addition to unfamiliar aspects of the construction and mechanical systems.

Design of Seismically Resistant Tree-Branching Steel Frames Using Theory and Design Guides for Eccentrically Braced Frames

R. Gary Black, Abolhassan Astaneh-Asl

The International Building Code (IBC) and the California Building Code (CBC) both recognize four basic types of steel seismic resistant frames; moment frames, concentrically braced frames, shear walls and eccentrically braced frames. Based on specified geometries and detailing, the seismic performance of these steel frames is well understood. In 2011 the authors designed an innovative steel braced frame system with tapering members in the general shape of a branching tree as a seismic retrofit solution to an existing four story “lift-slab” building. Located in the seismically active San Francisco Bay Area of California, a frame of this configuration, not covered by the governing codes, would typically require model or full scale testing to obtain jurisdiction approval. This paper describes how the theories, protocols, and code requirements of 
eccentrically braced frames (EBFs) were employed to satisfy the 2009 International Building Code (IBC) and the 2010 California Building Code (CBC) for seismically resistant steel frames and permit construction of these nonconforming geometries. Keywords— Eccentrically Braced Frame, Lift Slab Construction, Seismic Retrofit, Shear Link, Steel Design. 

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