Presented by David Herman, PE, LEED AP Principal, EnerG Associates, LLC

Energy Efficiency in

Multi-Tenant Office

Buildings

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Learning Objectives

1. List the principal sources and uses of energy in existing multi-tenant office buildings.

2. Identify energy-savings opportunities in existing multi-tenant buildings.

3. Understand the potential for savings through cost-effective building upgrades.

4. Recognize the value of the ENERGY STAR score as a tool to understand a building’s energy performance.

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• Building Energy Use Profile

• ENERGY STAR Score

• Building Energy Use Savings

• Building Energy Efficiency Measures

• Typical Office Building Example

• Building Stakeholders

Outline

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Average Office Building

Building Energy Use Profile

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Consumption per

Square Fool

Energy Use Intenstiy

(kBtu/sf)Cost per Square Foot

Electricity 15.5 kWh/sf 53.0 $1.60

Natural Gas 0.27 therms/sf 26.8 $0.31

Total 79.8 $1.91

Average Office Building

Building Energy Use Profile

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Building Energy Use Profile

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Average Office Building

• According to the Department of Energy, energy use is the largest operating expense in office buildings.

• The cost of maintenance and repairs is a close second.

Building Energy Use Profile

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What is the ENERGY STAR score?

• The ENERGY STAR score is a 1-to-100 assessment of a building’s energy efficiency, as compared with similar buildings nationwide.

• The score adjusts for climate and business activity.

• To qualify as an ENERGY STAR certified building, a building must be verified to earn a score of 75 or higher, indicating that the building performs better than at least 75% of similar buildings nationwide.

ENERGY STAR Score

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Improve energy use

• 30% -- amount of energy the average commercial building wastes

• 10% -- reduction of energy use with little or no cost

• 2.4% -- annual reduction of energy use for buildings that benchmark their energy use on a regular basis, on average

Building Energy Use Savings

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• A savings of 2.4% for three consecutive years is equivalent to the following for a 500,000 square foot office building:

–Cumulative energy cost savings -- $120,000

– Increase in asset value -- over $1 million

Building Energy Use Savings

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Benchmarking Savings

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• Energy efficiency: one step at a time

– Upgrades should be made throughout the entire property NOT just in common areas.

– A phased approach can help with financing and reduce any tenant inconvenience.

Building Energy Efficiency

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• Building recommissioning

• Lighting

• Building envelope

• Fans and motors

• Heating and cooling systems

• Controls

Building Energy Efficiency

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• Recommissioning is a systemic, documented process.

– Ensures building systems are operating according to the design intent, as well as the current needs of property owners and occupants.

– Identifies energy-saving opportunities.

• Recommissioning is an on-going process.

Building Recommissioning

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• Lighting upgrades offer a quick payback and an enhanced visual environment.

• Upgrading from T12 fluorescent lamps with magnetic ballasts to higher-efficiency T8 lamps with electronic ballasts can yield savings up to 25%.

Lighting

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• Upgrade and seal walls, roofs and windows.

– Improves occupant comfort.

– Reduces heating and cooling costs.

• Ensure insulation levels match recommendations in ASHRAE 90.1 Energy Standard for Buildings Except Low-Rise Residential Buildings.

Building Envelope

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• Converting constant volume systems to variable air volume units can reduce air flow by 40%.

• Installing variable speed drives can lower fan speed and reduce energy use by up to 50%.

Fans and Motors

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• Upgrading to more energy-efficient furnaces, boilers and air conditioning systems can reduce energy costs by up to 15%.

• Ensuring new energy-efficient systems are “right-sized” further saves energy.

– An oversized energy-efficient system will continue to waste energy.

Heating and Cooling Systems

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• Building energy-management system

• Programmable thermostats

• Occupancy sensors

Controls

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• Get everyone involved.

– Optimizing efficiency requires cooperation between building management and tenants.

• Education is key.

– Conserving energy benefits everyone.

• Form an energy team.

– Establish energy-saving goals.

– Implement a strategy.

Tenant Involvement

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• Baseline Building

– High-rise office building

– Chicago, IL

– 250,000 SF/800 occupants/900 computers

– 7 AM-6 PM Mon-Fri (55 hours per week)

– Centrifugal chiller/gas-fired hot water boiler

Typical Office Building Example

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• O&M/Recommissioning Measures – Optimize temperature set points – Optimize HVAC scheduling – Optimize ventilation to minimum required for code – Chilled water reset controls – Implement janitorial best practices – Power management enabling for PCs, printers and

copiers – Turn off plug loads at night – Specify ENERGY STAR equipment-office equipment,

vending machines

Typical Office Building Example

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• Lighting Measures

– Efficient lighting (high-performance T8/T5s, CFLS, LED exit signs)

– Occupancy sensors

– Perimeter daylighting controls

Typical Office Building Example

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• All Measures

– All O&M/recommissioning measures

– All lighting measures

– High-efficiency chillers

– Variable speed pumps and fans

– Premium efficiency motors

Typical Office Building Example

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Typical Office Building Example

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ScenarioElec Use

(kWh)

Elec

Savings

(kWh)

Elec

Savings (%)

Nat Gas

Use

(therms)

Nat Gas

Savings

(therms

Nat Gas

Savings (%)

Baseline 3,760,000 - - 109,500 - -

O&M 3,306,000 454,000 12% 90,500 19,000 17%

Lighting 3,471,000 289,000 8% 112,900 -3,400 -3%

All Measures 2,483,000 1,277,000 34% 98,100 11,400 10%

Scenario

Peak

Demand

(kW)

Demand

Reduction

(kW)

Demand

Reduction

(%)

Baseline 1,224 - -

O&M 1,169 55 4%

Lighting 1,164 60 5%

All Measures 877 347 28%

ScenarioAnnual EUI

(kBtu/SF)

EUI

Reduction

(%)

Eenrgy

Cost ($)

Energy

Savings ($)

EPA Energy

Rating

Baseline 95 - $482,078 - 62

O&M 81 15% $418,946 63,132 74

Lighting 93 3% $455,092 26,986 66

All Measures 73 23% $340,323 141,755 85

• Building owner

• Property manager

• Tenant

Building Stakeholders

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• Tenant – Reduce total cost of occupancy

• Owner – Increase net operating income

Increase return on investment

Building Stakeholders

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• Investing in energy efficiency increases asset value and makes available space more attractive.

• A phased approach to efficiency upgrades can help with financing and reduce tenant inconvenience.

• Optimizing energy savings requires a collaborative effort between property managers and tenants.

Key Points

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To download a copy of this presentation,

visit www.energengineers.com

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