SHEPHERD APARTMENTS RETROFIT PROGRAM


TABLE OF CONTENTS

Executive Summary

Introduction

Highlights & Process Goals

Development Process Goals

The Overview of Program Requirements

Process & Team

Design Process, Team & Scheduling

Performance Targets & Strategies

Building Audit & Analysis

Profiles of Energy/Water Use in Building

Potable Water Use

Natural Gas Consumption

Building Electrical Demand

Tenant Meter Electrical Consumption

Energy Consumption & Heating degree-days

Natural Gas Consumption

Electrical Consumption

Building meter

Tenant Meter

Water Consumption

Building Envelope & Air Barrier Systems

Computer Model

Air Tightness Tests of Suite

Building Ventilation

Heat Recovery from Ventilation Air

Retrofit Recommendations

Building Ventilation

Heat Recovery from Ventilation Air

Lighting

Exit Lights

Exterior Lights

Power Factor Correction

Space Heating Equipment

Domestic Water Heating

Chiller for Make-up Air Unit

Domestic Cold Water Supply

Heating & Cooling Equipment Maintenance

Elevators

Future Considerations & Opportunities

High Efficiency Motors

Roof Insulation

Wall Insulation

Soda Pop Machine

Cold Water Conservation

Summary

Lessons learned

Ecological impact

Performance Achieved



Executive Summary

 

In 1997 Saskatchewan Housing Corporation (SHC), embarked on a study of their multiple housing projects.  Ray Sieber, Energy Management Coordinator, coordinated the study for SHC.  Ray had promoted the study, in part, because of the urgent need to reduce building operating costs, which were significantly rising while budgets were not.  His other reasons were more philosophical, and reflected his personal, as well as SHC's corporate commitment, to support initiatives to reduce the impact of greenhouse gasses on climate change, which increasingly posed a threat to our environment.  SHC entered into a contract with Dr. Robert Dumont and his research team at Saskatchewan Research Council.  The energy audit protocols proposed for the study were described in the new Saskatchewan Building Energy Management (BEM) program.  The BEM program, was developed under the joint sponsorship of the Saskatchewan Research Council, Saskatchewan Energy & Mines, SaskPower and SaskEnergy.  The program objectives addressed most of Ray's expectations: 1) to reduce the operating cost of buildings in Saskatchewan, at reasonable cost to building owners, and 2) to give those who are responsible for the buildings an opportunity to learn about the energy use in their buildings and options to reduce it.  In the first year of the contract the BEM program audits were carried out at three Saskatchewan locations.  This case study, however, will focus on only one of the BEM audited buildings.  The subject building is the Shepherd Apartments, located at 535, 24th Street East, Saskatoon.  The study revealed energy retrofit costs of $36,075 with annual paybacks for retrofit of $18,823 resulting in a payback of 1.9 years. The BEM program was deemed to be a successful intervention.  To date thirteen projects have been audited under the BEM program and SHC have scheduled 3 more projects for audit in 2001.

Introduction

Highlights & Process Goals

 

The apartment is representative of several apartment projects owned by SHC within the province.  The clients demand an efficient, comfortable, secure and well-run building.

 

SHEPHERD APARTMENTS - SASKATOON

Photograph of Shepherd apartments
Saskatoon


SHEPHERD APARTMENTS - SASKATOON

Building type

Apartment building

Height

10 storeys

Total floor area

121,000ft2

Number of suites

186

Year of construction

1978

Exterior wall construction.


Brick exterior with metal studs and insulation between metal studs.  Rain cavity between brick and gypsum board on the exterior of metal studs.  Exterior is well maintained.

Windows

Sliding units with two single layers of glazing with aluminum frames and no thermal breaks.

Floors

Concrete

Roof

Upgraded with R15 and a torch applied exterior roofing membrane

Heating

Natural gas with hydronic (treated water) baseboard units.

Corridor Pressurization

Air heated in winter and chilled in summer.

Development Process Goals

 

The SHC is a strong advocate of reducing operating costs through effective energy management strategies.  Ray Sieber, Energy Management Coordinator, for SHC identified the new BEM, program as a suitable vehicle to assess performance of the corporations multiple housing stock.

The Overview of Program Requirements

 

In awarding the contract to SRC for the performance of energy audits on three multiple buildings, SHC’s expectations were straightforward. They required that the buildings be analyzed in order that sensible strategies could be identified to reduce operating costs and at the same time contribute to the reduction of greenhouse gasses into the environment.

Process & Team

Design Process, Team & Scheduling

 

The Building Energy Management (BEM), program uses an integrated assessment process, developed by the research team of Dr. Robert Dumont, Saskatchewan Research Council.  The BEM program evaluates the technical and financial aspects of the building and identifies potential energy efficiency options owners can employ to reduce energy use of the facility.  The effectiveness of the BEM program is contingent on ensuring that, with SRC, the clients and staff is fully involved and supportive of the program objectives.  The members of the team for this project are listed in the table below.

 

TEAM

Owner

SHC

Operator

Saskatoon Housing Authority

Energy Coordinator

Ray Sieber

On-site maintenance Engineer/Custodian

Jim Shearer

Saskatchewan Research Council

Dr. Robert Dumont
Larry Snodgrass

 

For example Mr. Jim Shearer, Maintenance Engineer, Shepherd Apartments, provided the team with invaluable information about the building's history and performance.  It was also imperative that Mr. Shearer be aware of the recommendations and implementation strategies.  After all, he would be responsible for coordinating and implementing the BEM recommendations on behalf of SRC and the Saskatoon Housing Authority.  The BEM schedule is described in the following table.

 

BEM SCHEDULE

Facility assessment & Energy Bench Marking

Obtain preliminary information to determine relative ranking of  facilities energy and water consumption

Technical Audit

On-site audit of energy using devices and systems

Evaluation of Cost Effective Options

Options are evaluated for cost effectiveness

Report Presentation

Report detailing recommended improvements is presented to facility owners.

Training

Provision of training to building operators

 

Performance Targets & Strategies

 

The BEM program requires their auditors to conduct an exhaustive analysis of the physical building and, as well, track consumption records to assess and verify current building performance.  Included in the study are, 1) to log energy and water use, 2) review drawings and building parameters, 3) conduct air tightness testing of a representative suite, 4) measure ventilation rates and heat recovery strategies, and 5) develop a computer model for building.

 

The information gathered is analyzed and the BEM audit identifies retrofit opportunities, which will result in savings for the facility owner.  In addition to the measures requiring investment, the auditor will recommend implementation of other maintenance practices that have no capital cost.

 

 

The BEM program provides advice on the type of products/materials used in the retrofit, for example,

v       no ozone depleting substances,

v      no materials that require CFC's or HFC's in their manufacture.

 

Building Audit & Analysis

Profiles of Energy/Water Use in Building

 

The energy and water consumption were tracked by reading the potable water, natural gas, tenant electrical and building electricity meters.

Potable Water Use

 

The peak water use occurred on two consecutive days between 9am and 9:30 am.  The consumption ranged from 2.69 m3/hour to 2.75 m3/hour.  The water consumption dropped, as expected, after midnight to a low of 0.74 m3/hour.  The reason that the consumption did not fall to zero was because of the demand of a water-cooled air-conditioner, which consumes about 0.43 m3/hour.  The water rate is $0.88/m3.  Over a month the water cost of the conditioner amounts to $253.

Natural Gas Consumption

 

Two boilers and three water heaters are the only appliances that use natural gas in the building.  One of the boilers is kept energized continuously.  Since the measurements were taken in the summer season there was likely no space heating demand.  The peak natural gas occurred at 10 am on August 21, 1997.  The flow amounted to 400 cu.ft. of gas for the hour time interval.  The minimum gas consumption occurred in the late evening and early morning at about 125 cu.ft. /hour.  The water heaters have individual pilot lights which each consume about 2 cu.ft. /hour.

Building Electrical Demand

 

Peak electrical demand is 106 kVa.  In the early morning hours, the demand drops to about 57 kV because elevator use and common area lighting is reduced.  It would be desirable to lower the peak kVa demand, as there is a monthly cost of about   $14/kVa for the peak above 50 kVa.  A number of electricity conserving measures that can be used to reduce peak Kva.load will be reviewed later in this case study.

 

 

Power factor correction equipment, a measure that can be installed to reduce kVa. demand, was already implemented in the Shepherd Apartment.

 

 

 

 

 

 

 

Tenant Meter Electrical Consumption

 

The peak electrical consumption of 130 kW occurred at 12:30 hours on August 21.  The lowest electrical consumption was 36 kW occurring in the early hours of the next day. The tenants each have an electric refrigerator and stove in addition to plug loads in each suite.  On each floor there is a laundry room with an electric washer and dryer.

 

 

Tenants are not charged for use of these appliances.  A recent survey showed that when tenants are billed, the consumption of electricity would be reduced by about 20% from those tenants that do not get billed.

 

 

The peak electrical load per suite averaged 0.68 kW.  The lowest electrical load per suite averaged 0.20 kW.  It should be noted, however, that several suites had window air conditioners, which can have peak loads of about 1 kW.

Energy Consumption & Heating degree-days

 

Natural gas and Electrical billing statements were collected for the complex. Consumption values were calculated for the periods between billing dates.  A second database containing past weather data for the building location was used for reference.  Total heating degree-days were calculated for the same billing periods as the consumption values and calculations compared on a per day basis.

Natural Gas Consumption

 

Natural gas consumption peaked in January 1997 at 1,989 cu.m. /day and during the same period total heating degree-days also peaked at 40.4 Celsius degree-days per day.  This corresponds to a mean daily temperature of -22.4 degrees over the 34-day billing period. 

 

 

The relationship is quite linear, with a slope of 44.6 m3/day per degree day/day and a y - intercept of 62 cubic meters/day.  The index of determination is equal to 0,995 [a perfectly straight line would have an index of determination of 1.00].  The slope of the line is a very useful measure, as the slope is an indicator of the total heat loss of the building relative to the temperature difference between inside and outside.  This slope value serves as a benchmark with which to compare before and after space heating consumption values.

 

 

Electrical Consumption

Building meter

 

Electrical consumption peaked in August 1997 at 75.9 kW and during the same period total heating degree days were at a near minimum value of 1.6 Celsius degree days/day.  The line representing building electrical consumption is linear but with two outer peaks.  This V shape is the result of the building having air conditioning loads in mid summer and high lighting and boiler pump loads in mid winter.

Tenant Meter

 

Tenant electrical consumption peaked in January 1997 at 107 kW and during the same period total heating degree days peaked at 42.5 Celsius degree days/day which corresponds to a mean daily temperature of -24.5 degree Celsius over the 28 day billing period.  Electrical consumption does not depend on temperature as drastically as natural gas but the decrease in daylight hours during the winter increases lighting loads.  The slope is 0.79 kW per degree day/day with a y - intercept of 60.4 kW.  The index of determination is 0.52.

Water Consumption

 

The water consumption is highest in the warmer weather due to lawn watering.

Building Envelope & Air Barrier Systems

Computer Model

 

Building parameters such as wall and window areas as well as wall and roof construction were calculated and tallied from the building blueprint and used as relevant data to develop a computer model for the building. 

 

 

The BEM program normally uses the HOT 2000 computer program and the building characteristics to develop a model of the buildings thermal performance.  The derived information would then be tested against historic weather data for its Saskatoon location.  Unfortunately, the HOT 2000 program has default maximum values that does not allow a building like Shepherd Apartments to be analyzed.

 

 

As a substitute, the auditors developed a spreadsheet-based model.  A printout of data for the Shepherd Apartments is shown in appendix “A”.  The upper part of the table calculates the heat loss of the building envelope at outdoor design conditions of –34oC.  This part of the heat loss amounts to 498 kW.  The air change rate of the building is then calculated using the known ventilation rate measured using a hot-wire anemometer traverse of the supply air duct for the building.  This flow was 6,495 L/s and the corresponding heat loss is 377 kW at –34oC.  As can be seen the heat loss due to forced air supply amounts to about 43% of the total building loss.  The sum of these two loads is 876 kW.  In addition to this load there is infiltration.  In order to check that the above heat loss calculations are approximately valid, a review of the natural gas bills was performed.  For the month of January 1997, the building used 1,989 m3/day at an average of 40.4 degrees Celsius-days per day.  Extrapolating to design conditions, the building consumption would be 2,375 m3/day.  The domestic hot water load is about 168 m3/day.  Thus the gross natural gas consumption for space heating is 2,560 - 168 = 2,207 m3/day.  This is equivalent to 945 kW. At a boiler efficiency of 80%, the useful space heat is 756 kW.  The electricity used in the building totals 198 kW in colder weather.  Almost all this electrical energy contributes to useful heat in the building.  Thus the total useful heat supplied is 756 + 198 = 954 kW, which compares roughly with the calculated load of 876 kW.  The difference between these two numbers is about 8%, and is most likely due to infiltration.  As can be seen, the ventilation and infiltration load is the largest single component of the total space-heating load.  The next largest is the walls at 34.7%.

Air Tightness Tests of Suite

 

A blower door apparatus was used to check the air tightness of a suite. The suite was as originally constructed.  The suite has an equivalent leakage area of 363 cm2.  For comparison, a suite measured at Temple Towers, Moose Jaw was tested, and it had a measured air leakage area of 520 cm2 before retrofit and 305 cm2 after retrofit.  While this provides a relative ranking the main purpose for the test was to identify specific leakage areas within the suite tested.  The assumption would be that these leakage areas would typically be found in other suites of the building.

Building Ventilation

 

The mechanical drawings for the building show recommended airflows of 47 L/s per suite (33 L/s for each bathroom and 14 L/s for each kitchen).  This ventilation rate is somewhat high.  The CSA Residential Mechanical Ventilation System Standard  (CAN/CSA - F326 - M91) requires only a total of 40 L/s (30 L/s per kitchen and 10 L/s per bathroom).  The drawings for the building show a design supply flow of 8,305 L/s; the measured flow was 6,495 L/s.

Heat Recovery from Ventilation Air

 

An outside air supply of 6,495 L/s was measured for the building.  This air supply pressurizes the hallways, enters the suites, is exhausted through the bathrooms and kitchens, and is eventually exhausted by fans in the upper part of the building.

 

The supply air fans are located in or near the mechanical room.  The exhaust air fans are located at different locations throughout the plan of the building.

Retrofit Recommendations

 

 

An energy management program can produce positive financial benefits.  A good energy management strategy includes both long term and short-term initiatives.  There are always methods to continue to reduce operating costs in a facility.  Employees, improved maintenance practices, and improved energy using equipment can do this with a combination of increased energy conservation awareness.

 

Building Ventilation

 

Even though the measured air supply flow is slightly less than that recommended by the CAN/CSA - F326 - M91 standard, the auditor does not recommend any modifications be made to the building ventilation strategy.  A survey of tenants or facility managers indicated no dissatisfaction with the indoor air quality.

Heat Recovery from Ventilation Air

 

The auditors calculated the cost of heating supply air to the building was about $14,000 per year. The auditors were, however, reluctant to recommend the installation of a heat recovery installation until a detailed study was undertaken.  They projected that a heat recovery system could recover about 70% of this heat and also recover some cooled air in the summer.  The auditor identified several implementation concerns, including:

·            Capital cost of installation.  Heat would have to be gathered from up to eight separate fan systems located throughout the plan of the building.

·            Additional fan electrical costs.  Saskatchewan has relatively high electricity prices and relatively low natural gas prices.  Auditors projected that with a designed heat ventilation system, about $10,000 could be saved in natural gas costs.  The cost, however, to install and operate additional fans using 10 kW of electricity would cost approximately $8,000 for a net saving of only $2,000.

·            Any heat recovery system would require low-pressure drop heat transfer surfaces, large duct sizes and efficient fans to minimize additional electrical energy costs for fans and pumps.

·            Maintenance costs.  These costs would increase due to the need for cleaning the heat exchange surfaces periodically and servicing the additional fans.

·            Space requirements for the heat exchanger.  In the existing mechanical room space is limited.

Lighting

 

Lighting was found to be a major user of electricity in the building.  The current interior lighting system in the building was systematically recorded and where appropriate a more conserving option was listed.  The auditors recommended that.

·            The existing fluorescent fixtures be retrofit using a combination of T-8 lamps, electronic ballasts and reflectors.

·            Retrofit of 2-lamp 4-foot fixture would reduce its power consumption from 93 watts to 30 watts.

·             Retrofit of 4-lamp T12 fixtures with 2 lamp T8's and a silver reflector would reduce its power consumption from 173 watts to 60 watts.

·            Retrofit of low wattage incandescent bulbs, (mainly 60 and 75 watt), with 13 watt compact fluorescent lamps.

·            Main hallway lights located in the areas surrounding the elevator be retrofitted with single T-8 lamps and reflectors.

·            The recessed fixtures located in the lobby area should be surfaced mounted.  A reduction of over 50% of the fixtures can be achieved without sacrificing any light level a reduction.

Exit Lights

 

Auditors recommended that the thirty-five rectangular exit signs, illuminated with 30 watts incandescent per fixture, be retrofitted with light emitting diode bulbs.  The fixture load will drop from 30 watts per fixture to about 4 watts per fixture.  The installation of the light emitting diode bulbs has a major labour saving advantage with their long life. Typically the light emitting diode bulbs are warranted for more than ten years.

 

 

Total annual electrical savings (which included demand savings) were estimated to be $10,938 with a simple payback of 2.2 years.

 

Exterior Lights

 

The auditors recommended that the twenty eight 75 watt incandescent lamps on the exterior of the building be retrofitted with 22 watt Panasonic compact fluorescent lamps that are rated for minus 30oC.  The two 450 watt mercury vapour fixtures located in the courtyard be retrofitted with 150-watt high-pressure sodium fixtures.  The remaining 75-watt high-pressure sodium fixtures presently do not have an economical replacement.

 

Power Factor Correction

 

Power Factor Correction FC was added to the building in 1993.  Sixty-two kVRA of capacitors were added reducing the peak kVA reading from 144 kVA to 122 kVA.  A substantial saving of about $300 per month in demand charges was realized. The auditor emphasizes that when the lighting retrofit is implemented the power factor should be re-examined because an over correction may occur.

 

 

Power Factor Correction (PFC) is the addition of capacitors to the system, which reduce the peak electrical demand.  Without PFC, the facility must be supplied with more electrical current than the equipment requires

 

Space Heating Equipment

 

The boilers are relatively new and since the efficiency ratings were above 80%, no boiler retrofit was recommended.  The combustion efficiency of the boiler was tested using an R.A.B. Dedesco meter that reads both the carbon dioxide and temperature rise.  At a 50% firing rate, the boiler had an estimated 84.6% efficiency rating based on a 208 degrees Fahrenheit temperature rise and a carbon dioxide concentration of 8.1% in the exhaust gases.  At a 100% firing rate the boiler had an 81.9% efficiency rating based on a 301 degrees Fahrenheit temperature rise and a carbon dioxide concentration of 8.1% in the exhaust gases.

Domestic Water Heating

 

The building has three domestic water heaters.  The units have an input rating of 720,000 Btu/h each and a recovery capacity of 10.1 USGPM.  The units have induced draft fans on them equal to 1/10 hp [3.25 Amperes at 120V].  The induced draft fans for the water heaters are wired in parallel.  Thus if one water heater is turned on, all three water heater induced draft fans are turned on.  Apparently this was done so as to prevent back drafting of the water heaters.

 

The combustion efficiency of one water heater was measured at 77.7% under steady state conditions, based on a 290oF.temperature rise and a carbon dioxide concentration of 4.9% in the exhaust gases.

 

The hot water temperature measured at the outlet of water heaters was equal to approximately 57.5oC to 58.1oC.  The hot water measured at suite 702 was 55oC.

 

 

Restricted flow on the liquid flow side of boilers or on the warm air side of the furnaces are often the key reason for low efficiency

 

 

The heating equipment is original to the building.  More efficient heating equipment is now available; however, the payback period on the cost of replacing the functioning equipment with higher efficiency equipment is longer than about eight years.  In the meantime, the equipment should be checked out each year for energy efficiency checks that can be performed.  The check involves measuring both the temperature rise and the carbon dioxide concentration in the flue gases.

 

New boilers and furnaces can have efficiencies in the range of 89% to 96% efficiency.  Existing boilers and furnaces are often in the range of 60% to 65% efficiency.

Chiller for Make-up Air Unit

 

A chiller tempers the make-up air that supplies the corridors and common areas.  The chiller unit is located on the roof.  An interesting retrofit had been performed on the make-up air for the building.  As originally built, the heat rejected from the chiller was exhausted in the vicinity of the fresh air intake for the building.  In addition, a dark coloured steel-sided wall was also adding heat to the intake air. By adding ductwork for the outside intake, the air is now being drawn in from a cooler part of the roof, thus reducing the need for cooling the fresh air.

 

The airflow is constant.  A duct traverse was performed in the mechanical room.  The airflow measured was 6,495 L/s [13800 cfm]

Domestic Cold Water Supply

 

The pump is located on the main floor adjacent to the water meters

 

 

Night Time Temperature Setback This energy conservation measure is not recommended for this facility, as almost all parts of the building are occupied through all hours.  In addition, the likelihood of freezing part of the building during night setback condition is greatly increased

 

Heating & Cooling Equipment Maintenance

 

Ensure equipment receives seasonal maintenance.  Filters should be cleaned, boiler efficiency should be checked, and fans and motors checked and lubricated according to the manufacturers specifications.  Dirty filters and fans can reduce operating efficiencies considerably, as they reduce the available airflow.

Elevators

 

The elevators are both in operation 24 hours per day.  In some high-rise buildings it is recommended for energy efficiency reasons to shut down some of the elevators during low hours of use.  In an apartment building with many seniors and handicapped persons it is not advisable.

Future Considerations & Opportunities

High Efficiency Motors

 

When motors fail, they should be replaced with energy efficient motors rather than a straight replacement of the identical motor.  The rate of return on higher efficiency motors is generally attractive.  More details about this topic can be found in the SRC “E” Notes series, which can be found on the       EMTF web pages.

Roof Insulation

 

A recent survey of roof life expectancies found that an average roof had a life expectancy of about 20 years – with maintenance.  As roofs are replaced, it is usually cost effective to add additional insulation.  The proposed energy code recommends levels of up to R26 for roofs on commercial buildings in Saskatchewan based on cost effectiveness criteria.  The existing roofs have R15 insulation

Wall Insulation

 

Walls in the apartment buildings have insulation placed between the steel studs.  It is not cost-effective to retrofit the walls on commercial buildings unless the walls are undergoing major repairs.  The heat loss per sq.ft. of the existing walls is about $0.25 per square foot per year.  Adding new insulation would generally cost between about $5 and $10 per square foot of wall surface.  Thus the payback is generally not cost effective unless major wall repairs are being undertaken.

Soda Pop Machine

 

A soda pop machine can consume a sizable amount of electricity.  A measurement of the electrical consumption of the soda machine on the main floor indicated an average consumption of 264 watts.  On an annual basis the machine consumes about $160.  Several inexpensive measures can be taken to reduce electricity consumption of these machines, including; delamping and installing a timer to shut off the cooler during periods at night when it is rarely used.  More details about this topic can be found in the SRC “E” Notes series, which can be found on the EMTF web page

Cold Water Conservation

 

Major cold water users inside the building are primarily toilets, baths, showers, washbasins and laundry. The use of cold water is a concern even though no energy cost is charged to the owner.  There is a cost for water and sewage charges.  The topic of cold water conservation measures can be reviewed in the SRC “E” Notes series, which can be found on the EMTF web page.

Summary

 

An energy management program can produce positive financial benefits.  Good energy management strategies include both long term and short term initiatives.  There are always methods to continue to reduce operating costs in a facility.  Employees, improved maintenance practices, and improved energy using equipment can do this with a combination of increased energy conservation awareness.

Lessons learned

Final audit unavailable - this section will be updated later

Ecological impact

Final audit unavailable - this section will be updated later

 

The predicted reduction of CO2, SO2, and Nox are all common greenhouse gases produced as a direct result of energy expenditures.  These gases increase the "greenhouse effect" which accelerates global climate change.  Based on achievement of recommendations the reduction of energy expenditures is….

Performance Achieved

Final audit unavailable - this section will be updated later

For more information regarding the Shepherd Apartment retrofit program contact Dr. R. Dumont, Saskatchewan Research Council Tel: 1(306) 933-6216 or R. Sieber P. Eng., Saskatchewan Housing Corporation Tel: 1(306) 787-0032