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EMRAs research endeavors have ranged from multi year research involving vast amounts of data collection to examine major energy systems loads and operations in portfolios of buildings to review of existing data sets and literature searches to evaluate the effectiveness of energy savings products.Research (for page with write-up) - Recirc 1

Multi-Family Building Energy Monitoring and Analysis, Heating Plant and Domestic Hot Water Sizing Criteria Development

In this NYSERDA (New York State Energy Research & Development Authority) funded project, Energy Management & Research Associates compiled the largest known database on multi-family building heating plant operation and hot water usage. Analysis of the data has resulted in precise DHW consumption curves for hot water system sizing, as well as figures for use in energy audit and engineering calculations. Previously, most installers relied on “rule-of-thumb” sizing procedures which resulted in oversizing and overheating with considerable waste of fuel.

The study deals with 30 buildings, concentrating on a core of buildings which were strictly evaluated using sophisticated monitoring equipment. The results of this work were reviewed by ASHRAE’s Technical Committee 6.6 (Service Hot Water), and a new set of DHW sizing guidelines (authored by Mr. Goldner) was adopted for inclusion in the revision of DHW standards that first appeared in the 1995 edition of the ASHRAE Handbook, as well as the 1998 American Society for Plumbing Engineering’s (ASPE) Domestic Water Heating Design Manual.

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DHW Recirculation System Control Strategies

This study was the third step in a series of research projects that examined domestic hot water (DHW) issues in multi family buildings. The research analyzed the effects of varying control strategies of DHW recirculation systems in multi family buildings. The question examined was whether it is necessary to continuously run recirculation pumps (as is general practice), or could DHW system energy consumption be reduced by operating the pumps with some type of control strategy? The project investigated this issue by analyzing a series of four different control strategies, employing detailed monitoring to closely observe the effects of each strategy. The four different operating strategies were: A) continuous operation (base case); B) shut down during the overnight period; C) shut down during the peak morning and evening periods; and D) cycled by a return line aquastat set at 110o F.

The analysis revealed that as compared to the base case (pump running 24 hours per day), Strategy B saved an average of 6%, Strategy C saved 6%, and Strategy D saved 11% of the DHW portion of a building’s annual energy requirements. This is significant, as Strategy D translates into a savings of 4% of the building’s total yearly fuel bill. As all of the rather simple control strategies evaluated employ low cost devices (under $250 installed), this should insure an extremely large penetration rate for the control strategy recommendation.

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