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Energy-Efficient HVAC Upgrade for Office Building in Iowa, USA

Project Overview

Business Needs/Problem Statement

A 100,000 sq. ft. commercial office building constructed in the early 1990s in Iowa, USA, is experiencing high energy costs and inefficient HVAC (Heating, Ventilation, and Air Conditioning) systems.

Building Type

Commercial Office Building

Size

100,000 sq. ft

Location

Iowa, USA

Inputs from Client

  • Our 100,000 sq ft office building in Iowa, developed in the 1990s, has high energy costs due to inefficient HVAC systems. We need to upgrade to energy-efficient systems to reduce expenses and improve tenant comfort.

Applicable Codes and Standards

  • ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers)
  • ASHRAE 90.1: Energy Standard for Buildings Except for Low-Rise Residential Buildings
  • ASHRAE 62.1: Ventilation for Acceptable Indoor Air Quality
  • IECC (International Energy Conservation Code)
  • IECC 2018: International Energy Conservation Code
  • NFPA (National Fire Protection Association)
  • NFPA 70: National Electrical Code (NEC)
  • IBC (International Building Code)
  • IBC 2018: International Building Code
  • LEED (Leadership in Energy and Environmental Design)
  • LEED v4: Green Building Rating System (optional but often pursued for sustainability)

Challenges Faced

  • High Energy Costs: Existing HVAC systems are outdated and inefficient, leading to excessive energy consumption and high operating costs.
  • Comfort Issues: Inconsistent temperatures and poor indoor air quality affect tenant comfort and productivity.
  • Code Compliance: The building does not meet current energy efficiency standards outlined in IECC, ASHRAE, and local codes.

Our Solutions /Approach

Energy Audit and Analysis

  • Conducted a comprehensive energy audit to identify inefficiencies and quantify potential energy savings.
  • Used software tools that are compliant with ASHRAE guidelines for energy simulation (e.g., EnergyPlus) to model potential energy savings.

Energy Recovery and Control Systems

  • Implemented heat recovery ventilators (HRVs) and energy recovery ventilators (ERVs) to optimize ventilation and reduce heating/cooling loads.
  • Integrated a Siemens Desigo CC BAS for centralized control of HVAC, lighting, and occupancy sensing systems.

Selection of Energy-Efficient Equipment

  • Selected HVAC equipment (Chiller, Boiler, AHUs, FCUs, etc.) that meets or exceeds the energy efficiency standards set by ASHRAE and IECC.
  • Ensured compliance with NFPA 70 for electrical installations and IBC for structural considerations related to equipment placement.

Integration of Building Information Modeling (BIM)

  • Developed a detailed BIM model of the building to visualize existing conditions and plan retrofit strategies.
  • Coordinated MEP (Mechanical, Electrical, Plumbing) systems within the BIM environment to optimize space utilization and ensure clash-free installations.

Renewable Energy Integration

  • Evaluated the feasibility of future solar PV installation on the building’s roof to offset electricity consumption.

LEED Considerations

  • Pursued LEED certification, focusing on energy efficiency, indoor environmental quality, and sustainable materials.

Components for Retrofitting HVAC System

1. HVAC Equipment Selection:

Chiller/Heat Pump:

  • Selected high-efficiency models compliant with ASHRAE and IECC standards.
  • Variable speed drives (VSD) were considered for better energy management.

Manufacturer: Carrier

Rating:

  • Cooling Capacity: 500 tons
  • Efficiency Rating: IPLV (Integrated Part Load Value) of 0.65

Nameplate:

  • Capacity: 500 tons
  • Voltage: 460V
  • Refrigerant: R-134a
  • Efficiency: SEER (Seasonal Energy Efficiency Ratio) of 15

Boiler/Furnace:

  • Choose condensing boilers or high-efficiency furnaces to maximize energy savings.
  • Ensured compliance with local emission standards and safety codes.

Manufacturer: Trane

Rating:

  • Heating Capacity: 5,000,000 BTU/h
  • Efficiency Rating: AFUE (Annual Fuel Utilization Efficiency) of 90%

Nameplate:

  • Capacity: 5,000,000 BTU/h
  • Fuel Type: Natural Gas
  • Efficiency: AFUE 90%

Air Handling Units (AHUs):

  • Upgraded to AHUs with variable air volume (VAV) systems for better control.
  • Integrated energy recovery systems to capture and reuse waste heat.

Manufacturer: Johnson Contro

Rating:

  • Airflow: 50,000 CFM
  • Fan Efficiency: 70%

Nameplate:

  • Capacity:50,000 CFM
  • Voltage: 230V/3-phase
  • Fan Efficiency:70%

Fan Coil Units (FCUs)/VAV Boxes:

  • Replaced outdated units with energy-efficient models.
  • Opted for units with programmable controls for better temperature management.

Manufacturer: Daikin

Rating:

  • Airflow: 4,000 CFM
  • Static Pressure: 1 inch

Nameplate:

  • Capacity: 4,000 CFM
  • Voltage:120V/1-phase

2. Control Systems

Building Automation System (BAS):

  • Implemented a centralized BAS for monitoring and controlling HVAC operations.
  • Integrated with BIM for real-time data visualization and optimization.

Manufacturer: Siemens

Nameplate:

  • Model: Desigo CC
  • Protocol:BACnet/IP
  • Capabilities: HVAC control, lighting integration, occupancy sensing

Thermostats and Sensors:

  • Installed programmable thermostats with occupancy sensors to adjust HVAC settings based on occupancy.
  • Used CO2 sensors for demand-controlled ventilation to improve indoor air quality.

3. Ductwork and Distribution System

Duct Insulation:

  • Ensured proper insulation of ducts to minimize heat loss or gain.

Air Distribution Design:

  • Optimized duct layout to reduce pressure drops and improve airflow distribution.
  • Sealed duct joints and connections to prevent air leaks.

4. Energy Recovery Systems

Heat Recovery Ventilators (HRVs) / Energy Recovery Ventilators (ERVs):

  • Installed HRVs/ERVs to recover heat or coolness from exhaust air to precondition incoming fresh air.
  • Enhanced indoor air quality while reducing heating/cooling loads.

5. Lighting and Controls Integration

Lighting Upgrades:

  • LED lighting retrofits were considered to reduce internal heat gains.
  • Integrated lighting controls with HVAC controls for coordinated energy management.

Manufacturer: Philips Lighting

Rating:

  • Efficacy: 100 lumens per watt
  • Colour Rendering Index (CRI): 80

Nameplate:

  • Wattage: 45W
  • Colour Temperature: 3500K
  • Rated Lifespan: 50,000 hours

6. Building Envelope Improvements

Windows and Glazing:

  • Upgraded to energy-efficient windows with low-E coatings and improved insulation.

Manufacturer: Pella Corporation

Rating:

  • U-Factor: 0.30
  • Solar Heat Gain Coefficient (SHGC): 0.35

Nameplate:

  • Type: Low-E, Double-pane
  • U-Factor: 0.30
  • SHGC: 0.35

Insulation

  • Enhanced building insulation levels to reduce heating and cooling loads.

Manufacturer: Owens Corning

Rating:

  • R-Value: R-20

Nameplate:

  • Insulation Type:Fiberglass
  • R-Value: R-20

7. Water Heating System

Water Heaters/Boilers:

  • Replaced outdated water heaters with high-efficiency models.
  • Tankless water heaters are considered for on-demand hot water supply.

8. Renewable Energy Integration

Solar PV Systems:

  • Assessed the feasibility of installing rooftop solar panels to offset energy consumption.
  • Proposed Integration of solar energy production with HVAC and electrical systems.

9. Maintenance and Monitoring

Commissioning and Retro-commissioning:

  • Conducted thorough commissioning to ensure all HVAC components operated as designed.
  • Scheduled regular maintenance to optimize system performance and longevity.

Impact / Result

By implementing a comprehensive retrofit plan that integrates modern HVAC systems, adheres to relevant codes (NEC, NFPA, IBC, IECC, ASHRAE), and utilizes BIM for design and coordination, the building owner has achieved significant energy savings and improved tenant comfort.

This approach not only addresses the initial problems of high energy costs and comfort issues but also ensures compliance with current building regulations and sustainability standards.

The upgraded systems have enhanced operational efficiency, reduced environmental impact, and positioned the building for long-term cost savings and increased asset value.

Energy Savings: Estimated 30% reduction in energy consumption post-retrofit.

Cost Savings: Projected payback period of 5 years based on reduced utility costs.

Occupant Comfort: Improved indoor air quality and temperature control, enhancing tenant satisfaction and productivity.

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©2025 Edifice Expert. All rights reserved.
  • 42 Washington St. Ipswich MA 01938 (USA)
  • 42 Washington St. Ipswich MA 01938 (USA)
  • 42 Washington St. Ipswich MA 01938 (USA)
©2025 Edifice Expert. All rights reserved.

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