article hosptial upgrade

8/12/2019 ARTICLE Hosptial Upgrade

http://slidepdf.com/reader/full/article-hosptial-upgrade 1/3

SECOND PLACE: HEALTH CARE FACILITIES. EXISTING

Heat Recovery Geothermal Save Energy

UPGR DEy Jack Kafesdjian Eng. Member ASHRAE

Montreal's Louis-H. Lafontaine Hospital is a 140-year

old psychiatric hospital that at its peak housed as

many as 5,000 patients. Historic buildings of this type offer

many opportunities for energy savings. Designers identified 26

energy-saving measures for the 1 5 million ft 2 ( 139 355 m2)

hospital, and the hospital administration selected 1 8 based on Montreal's Louis-H Lafontaine Hospital reduced energy con

sumption by 15 , with a projected yearly decrease of 2,387

available funds (see Energy Saving Measures sidebar).

The initial energy efficiency study performed in 2005- 06,

revealed that the annual energy consumption for the hospi

tal in the previous year was approximately 64 million kWh

(230 400 GJ) or 44 kWh/ft2 (473 kWh/m2) at 0.04/kWh

( 11.11/GJ). This equated to roughly 2.4 million in annual

energy costs (in 2003 04 dollars) and was split between

three energy sources: natural gas (70%); electricity (18%)

and fuel oil (12%).

The study showed that the annual energy savings potential

was roughly 850,000. The construction costs were estimated

at 6 million, and the original project payback period was

seven years (maximum allowable for government funding).

The financial savings estimated for this project are based on

the following utility rate structure (from 2006):

• Electric demand: 12.60/kW;

• Electric consumption: 0.0256/kWh;• Natural gas: 0.40fm3 ( 0.01 /ft3); and

• Fuel oil No.2: 0.41/L ( 1.55/gallon).

44 ASHRAE Journal

tons of greenhouse gas emissions.

The first 29 months of operation beginning in November

2006 and ending in March 2009 generated a substantial reduc

tion of more than 1.5 million or 20.8 million kWh (74 850

GJ) in energy consumption. The period from March 2009 to

March 2010 generated a reduction of 800,000 or 9,335,000

kWh (33 600 GJ) , which is closely aligned to the predicted

annual savings.This represents a 14 .6% reduction ofthe total

energy consumption for the hospital.

The energy reduction is mainly achieved using boiler stack

heat recovery and geothermal energy to heat domestic hot wa

ter. It does not include ventilation and air-conditioning ~ v i n g sbecause a large portion of the hospital has neither system. Large

portions of the hospital were not evaluated due to upcoming

renovation projects to address the lack of adequate ventilation.

bout the uthor

Jack Kafesdjian, Eng., is the techn ica l director at EnerCible, a department of

SNC-Lava lin s TIB division in Montrea l.

ashrae.org August 2011



he 140-year-old hospital housed approximately 5,000 patients at its peak.

The most innovative and important

measure ofthis project is using the exist

ing 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 con

sists simply of a stainless steel indirect

type heat exchanger in which the watercirculates and is heated via the flue gases.

The quantity of flue gas drawn from the

main chimney is controlled by the vari

able 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 oc

curs 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 wasevaluated at 70,000 gallons (264 979 L)

per day in the winter.

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 Lis]), 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 he winter. This same strategy was used

for the laundry room HVAC unit (30 ,000

cfm [14 158 Lis] 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 500ft 152m)

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

nergy 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

Sensible and latent heat reclaim

from the chimney stacks to preheat

boiler feed water and domestic hot

waterProduction 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 pressuresteam boilers 950 bhp [708 kW]

total capacity)Building envelope improvements

(sealing of more than 4 ,300

windows or 150,000 line\]r 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 line ar 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 cool

ing tower that would then exhaust the

condenser-side energy to the environment

throughout the year, instead of reusing

it in the winter. Another measure wasthe addition of two water-to-water heat

pumps of 7.5 tons (26 kW) of capacity

SHR E ournal 45



Geothermal well digging equipment dug 6 vertical wells to produce domestic hot water

each in series with the condenser side

circuit going to the cooling tower to heat

the space, instead of using steam, and

reuse this otherwise lost energy.

The modifications performed to the

building envelope greatly reduced

the heating energy requirements and

also improved the comfort conditionsfor the entire hospital's population in

winter. More than 4,300 windows or

the equivalent of 150,000 linear ft (45

720 linear m) or 28 miles ( 45 km) in

length, were sealed to reduce the heat

loss in the winter and reduce cold air

draft problems. Each winter patients,

doctors and sta ff raised concerns about

these problems to the hospital s ad

ministration department over the past

several years.

Practically no HVAC-related me

chanical improvement measures were

implemented in this energy-efficiency

project because of the minimal amount

of existing space and air conditioning

equipment in the hospital. Eighty-five

percent of the spaces are handled by

natural ventilation in conjunction with

several original exhaust fans , which

was the original design used to provide

the minimal air changes required. Also,

these same spaces are mainly heated

by steam radiators in winter. Future

building improvement and renovation

46 ASHRAE Journal

projects also include adding further

space conditioning to improve the en

vironment where patients, doctors and

personnel reside.

One building's perimeter that was

originally heated by a constant high tem

perature hot water loop provided from

a steam/hot water heat exchanger, wasimproved by implementing an indoor

outdoor temperature control strategy.

Previously, the only way to adequately

control room temperature (generally

higher on the south facing side because

of additional sun load) was to open

windows when it was too hot in the

room. This was common practice even

when the outdoor temperature was well

below freezing.

In addition, the existing pneumatic

controls for the heating were upgradedwith state-of-the-art direct digital con

trols to improve energy efficiency, com

fort conditions and to reduce energy,

regular maintenance and major repair

expenditures as well.

Bi-metallic room thermostats used for

the electric baseboards in the Fernand

Seguin Research building (an adjacent

and more recent construction from 1991)

were also replaced by electronic and pro

grammable models to control the room

temperature more accurately and also

implement a night-setback strategy.

ashrae .org

uilding t a Glance

Name: Louis-H. LaFontaine Hospital

Location: Montreal

Owner: Provincial Government of

Quebec

Principal Use: Hospital

Includes: Admin istrative offices,

cafeteria , warehouse, laundry

facilities, research center

Employees/ Occupants : 120/ 1 ,200

Gross Square Footage: 1.5 million

Conditioned Space: 22 5 ,000

Substantial Completion/ Occupancy:

Retrofit completed in 2006

This project also received substantial

grants from both local energy providers,

Gaz Metro and Hydro-Quebec. The total

amount attributed to the hospital was

$185 ,000 ($108,000 by Gaz Metro and

$77,000 by Hydro-Quebec).The hospital administration under

stood from the beginning of this project

that to decrease the annual operational

expenditures and energy consumption

for the hospital, new heat reclaim and

more efficient equipment were neces

sary. Because of the minimal operations

staff and personnel available on-site,

the equipment for this project was

selected with special care so that ad

ditional staff will not be required in

the future.The geothermal system and new elec

tric steam boiler are solely run during off

peak hours, permitting the more efficient

use of electric energy and eliminating

the need to construct further dams and

hydroelectricity generating plants to

supply the ever increasing electric energy

demand and use.

The 15% reduction of energy consump

tion will generate a yearly decrease in the

production of 2,387 tons of greenhouse

gas (GHG) emissions or the equivalent

of 682 cars.•

August 2011

article hosptial upgrade

Documents