ASHRAE Journal - August 2011 - 45

technology award case studies
Energy Saving Measures
Storage of high temperature domestic hot water in a 100,000 gallon (378 541 L) tank Production of domestic hot water via an off-peak geothermal system of 150 tons (528 kW) of capacity and 18,000 linear ft (5486 linear m) of vertical wells

The 140-year-old hospital housed approximately 5,000 patients at its peak. The most innovative and important measure of this project is using the existing 100,000 gallon (378 541 L) storage tank that had once stored non-potable water for fire suppression purposes. In the winter, the tank now stores high temperature domestic hot water at 180°F (82°C) that is produced by the latent heat reclaim unit installed on the boiler stacks. The latent heat reclaim system consists simply of a stainless steel indirect type heat exchanger in which the water circulates and is heated via the flue gases. The quantity of flue gas drawn from the main chimney is controlled by the variable speed fan and set according to the desired water output temperature. The annual city water consumption used for domestic hot water and boiler makeup water was high. This motivated the hospital administration to enhance the efficiency of the unit to the maximum since it fully condenses the flue gases when below 130°F (54°C), which occurs during most of the operating time. The lowest chimney exhaust temperature recorded was 70°F (21°C). This is a huge gain from the traditional 550°F (288°C) flue gas temperature seen in the past. This energy (about 15%) was formerly lost because of the lack of a heat reclaim system. Currently, it is being used to preheat the boiler feed water and also to entirely heat the domestic hot water consumption of the hospital, which was evaluated at 70,000 gallons (264 979 L) per day in the winter.
August 2011

Each of the two boiler feed water pumps, which operated in the past at constant flow, also has been replaced with four multistage variable speed pumps that now operate according to the actual boiler steam load. The existing boiler combustion makeup air unit (12,500 cfm [5899 L/s]), which consisted of an indirect-fired gas burner, was modified to insert a glycol coil. The heat from the new domestic water loop at 180°F (82°C) was used via a heat exchanger to preheat the incoming combustion air instead of using natural gas during most of the winter. This same strategy was used for the laundry room HVAC unit (30,000 cfm [14 158 L/s] of 100% fresh air) that was preheated and heated by two separate steam coils in the past. During the summer, the closed-loop geothermal heat pump system of 150 tons (528 kW) of capacity combined with 36 vertical wells of 500 ft (152 m) of depth or a total of 18,000 linear ft (5486 linear m), produce the domestic hot water requirements. In addition, it is only operated during off-peak periods to optimize the electric use factor. Since the heat pumps can only produce a maximum water temperature of 120°F (49°C), the new 1 MW off-peak electric steam boiler increases the domestic hot water temperature to 145°F (63°C) via a heat exchanger. The water is then stored in the reservoir. The warehouse of the hospital was heated in the winter by several suspended

Sensible and latent heat reclaim from the chimney stacks to preheat boiler feed water and domestic hot water Production of domestic hot water via an off-peak 1 MW electric steam boiler Variable speed multistage boiler feed water pumps Direct digital controls replacing old pneumatic controls Micro-modulation of natural gas and fuel oil burners for high pressure steam boilers (950 bhp [708 kW] total capacity) Building envelope improvements (sealing of more than 4,300 windows or 150,000 linear ft or 28 miles [45 720 linear m or 45 km]) Lighting retrofit of 3,100 fixtures from T12 fluorescent lamps and magnetic ballasts to high-efficiency T8 fluorescent lamps and electronic ballasts High pressure steam piping thermal insulation of 9,000 linear ft (2743 linear m)

steam unit heaters but also contained five cold rooms to preserve the frozen and refrigerated foods. These cooling units were connected to a common cooling tower that would then exhaust the condenser-side energy to the environment throughout the year, instead of reusing it in the winter. Another measure was the addition of two water-to-water heat pumps of 7.5 tons (26 kW) of capacity
ASHRAE Journal 45



ASHRAE Journal - August 2011

Table of Contents for the Digital Edition of ASHRAE Journal - August 2011

ASHRAE Journal - August 2011
Contents
Commentary
Industry News
Letters
Meetings and Shows
Feature Articles
2011–12 Presidential Address: Sustaining ASHRAE Through Leadership
Retrocommissioning Older Buildings
Liquid Refrigerant Pumping in Industrial Refrigeration Systems
Technology Award Case Studies:
Hospital Upgrade: Heat Recovery, Geothermal Save Energy
Cool Weather Savings: Using Hybrid Refrigeration Systems for Chiller Retrofit
Special Section
InfoCenter
Standing Columns
Solar NZEB Project
Emerging Technologies
Special Products
IAQ Applications
Washington Report
People
Products
Classified Advertising
Advertisers Index
ASHRAE Journal - August 2011 - Intro
ASHRAE Journal - August 2011 - ASHRAE Journal - August 2011
ASHRAE Journal - August 2011 - Cover2
ASHRAE Journal - August 2011 - 1
ASHRAE Journal - August 2011 - 2
ASHRAE Journal - August 2011 - Contents
ASHRAE Journal - August 2011 - Commentary
ASHRAE Journal - August 2011 - 5
ASHRAE Journal - August 2011 - Industry News
ASHRAE Journal - August 2011 - 7
ASHRAE Journal - August 2011 - 8
ASHRAE Journal - August 2011 - 9
ASHRAE Journal - August 2011 - Letters
ASHRAE Journal - August 2011 - 11
ASHRAE Journal - August 2011 - 12
ASHRAE Journal - August 2011 - 13
ASHRAE Journal - August 2011 - 14
ASHRAE Journal - August 2011 - 15
ASHRAE Journal - August 2011 - Meetings and Shows
ASHRAE Journal - August 2011 - 17
ASHRAE Journal - August 2011 - 2011–12 Presidential Address: Sustaining ASHRAE Through Leadership
ASHRAE Journal - August 2011 - 19
ASHRAE Journal - August 2011 - 20
ASHRAE Journal - August 2011 - 21
ASHRAE Journal - August 2011 - 22
ASHRAE Journal - August 2011 - 23
ASHRAE Journal - August 2011 - 24
ASHRAE Journal - August 2011 - 25
ASHRAE Journal - August 2011 - Retrocommissioning Older Buildings
ASHRAE Journal - August 2011 - 27
ASHRAE Journal - August 2011 - 28
ASHRAE Journal - August 2011 - 29
ASHRAE Journal - August 2011 - 30
ASHRAE Journal - August 2011 - 31
ASHRAE Journal - August 2011 - 32
ASHRAE Journal - August 2011 - 33
ASHRAE Journal - August 2011 - 34
ASHRAE Journal - August 2011 - 35
ASHRAE Journal - August 2011 - Liquid Refrigerant Pumping in Industrial Refrigeration Systems
ASHRAE Journal - August 2011 - 37
ASHRAE Journal - August 2011 - 38
ASHRAE Journal - August 2011 - 39
ASHRAE Journal - August 2011 - 40
ASHRAE Journal - August 2011 - 41
ASHRAE Journal - August 2011 - 42
ASHRAE Journal - August 2011 - 43
ASHRAE Journal - August 2011 - Hospital Upgrade: Heat Recovery, Geothermal Save Energy
ASHRAE Journal - August 2011 - 45
ASHRAE Journal - August 2011 - 46
ASHRAE Journal - August 2011 - 47
ASHRAE Journal - August 2011 - Cool Weather Savings: Using Hybrid Refrigeration Systems for Chiller Retrofit
ASHRAE Journal - August 2011 - 49
ASHRAE Journal - August 2011 - 50
ASHRAE Journal - August 2011 - 51
ASHRAE Journal - August 2011 - InfoCenter
ASHRAE Journal - August 2011 - 53
ASHRAE Journal - August 2011 - 54
ASHRAE Journal - August 2011 - 55
ASHRAE Journal - August 2011 - 56
ASHRAE Journal - August 2011 - 57
ASHRAE Journal - August 2011 - 58
ASHRAE Journal - August 2011 - 59
ASHRAE Journal - August 2011 - 60
ASHRAE Journal - August 2011 - Solar NZEB Project
ASHRAE Journal - August 2011 - 62
ASHRAE Journal - August 2011 - 63
ASHRAE Journal - August 2011 - 64
ASHRAE Journal - August 2011 - 65
ASHRAE Journal - August 2011 - Emerging Technologies
ASHRAE Journal - August 2011 - 67
ASHRAE Journal - August 2011 - 68
ASHRAE Journal - August 2011 - 69
ASHRAE Journal - August 2011 - 70
ASHRAE Journal - August 2011 - 71
ASHRAE Journal - August 2011 - 72
ASHRAE Journal - August 2011 - 73
ASHRAE Journal - August 2011 - 74
ASHRAE Journal - August 2011 - Special Products
ASHRAE Journal - August 2011 - IAQ Applications
ASHRAE Journal - August 2011 - 77
ASHRAE Journal - August 2011 - 78
ASHRAE Journal - August 2011 - 79
ASHRAE Journal - August 2011 - Washington Report
ASHRAE Journal - August 2011 - 81
ASHRAE Journal - August 2011 - People
ASHRAE Journal - August 2011 - 83
ASHRAE Journal - August 2011 - Products
ASHRAE Journal - August 2011 - 85
ASHRAE Journal - August 2011 - Classified Advertising
ASHRAE Journal - August 2011 - 87
ASHRAE Journal - August 2011 - Advertisers Index
ASHRAE Journal - August 2011 - Cover3
ASHRAE Journal - August 2011 - Cover4
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