A Quantitative Study of the Viability of Greywater Heat Recovery (GWHR): GWHR Implemented in Barracks and Dining Facilities

Abstract

This quantitative study examined the economic viability of using greywater heat recovery (GWHR) systems for barracks, and dining facilities on Army installations. Both training (open bay type) and "1 + 1" type barracks were studied independently due to their configuration differences. This study discusses the technology theory, installation, and expected costs and savings. Theoretical analysis is done using a variety of thermal effectiveness and savings data from independent studies, assumed water usage levels for barracks and dining facilities, and actual fuel cost data. The analytical study determined that it was economically viable, in most cases, to install GWHR systems in training barracks and in dining facilities. In almost every case, both facility types would have short payback periods and have correspondingly high savings to investment ratios. Results for a "1 + 1" barracks configuration show GWHR viability only with high energy costs and a high number of floors. Finally, this study will provide a decision tool regarding the installation of GWHR systems for barracks and dining facilities based on various energy costs and size of facility. DISCLAIMER:The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR. ERDC/CERL TR-11-20 iii Executive SummaryThis quantitative study determined that it is economically viable to install greywater heat recovery (GWHR) systems in training barracks and in dining facilities. In almost every case, both facility types would have short payback periods and correspondingly high savings-to-investment ratios. Results show that GWHR systems are most viable for barracks with a "1 + 1" configuration with a higher number of floors (and higher initial energy costs).In 2006, the "Canadian Centre for Housing Technology" conducted a performance evaluation (Zaloum, Gusdorf, and Parekh 2006) of several GWHR technologies to determine effectiveness values and energy savings for five GWHR systems. These performance and savings values were used to determine theoretical energy savings for this study.To determine applicability to Army facilities, energy consumption in barracks was estimated based on facility size, estimated showering water use, and yearly occupation. For dining facilities, water usage was estimated based on facility capacity, estimated number of daily customers, and expected annual operating days. Geographic location was not considered.Results showed that, based on simple payback and savings to investment ratio (SIR) values, it is viable to install GWHR systems in almost all cases.Tables ES1 and ES2 su...

A Key Review of Non-Industrial Greywater Heat Harnessing

“…As evident, the average usage per person is about 140-150 L. An estimate from the Oak Ridge National Lab is that a person produces about 136 L per day [31]. In terms of individual appliances, showers consume most of the water, as depicted in Figure 7.…”

“…On an average, the flow rate of a shower head is 12 L/min. This computes to about 70 L of shower water generated per day [31]. Comparatively, when a bath is taken in a tub, about 80 L of water are used [13].…”

“…In another study, the potential to harness heat from common bathrooms and the dining facilities in army barracks, was analysed [31]. For the showering facilities, it was estimated that one cadet, had a daily usage of about 50 L. Considering 400-600 cadets in a barrack, the upper limit of the usage would be about 30,600 L per day, at about 30-50 • C. A general dining hall in the US military, provides meals to about 400-600 cadets per day.…”

“…However, both these types are more prone to fouling and suffer a considerably loss of efficiency with contaminants, as in the case of GW. Usually with GW the shell and tube type, consists of a large GW storage tank with spiral cold water tubes within [31]. Sometimes the tubes are within it, or on the circumference to avoid biofilm deposits.…”

“…A list of the different type of HEs, with details of commercial manufacturers and costs, is summarized in Table 3 [31,35,43]. Options (a) and (c) are both balanced, i.e., demand and supply flow rates are equal, but (a) has more flexibility.…”