High Performance Ventilation for Multi-Family Buildings

- Case Studies -

Galen Staengl, PE LEED BD&C Certified Passive House Consultant Principal Staengl Engineering

Ventilation System Design for Multi-Family Buildings

Design Objectives 1. Maintain Healthy Indoor Environments

• Provide Fresh Air – Dilute Air Contaminants • Control Humidity in Ventilation Air and Building

2. Minimize Building Energy Consumption 3. Minimize Cost of System and Cost of

Ownership The Best Strategies Vary Based on Factors Such as

Building Height and Unit Size.

Governing Codes

ASHRAE 62.1 • Applies to Multi-Family 4 Stories and Greater • Does Allow Natural Ventilation ASHRAE 62.2 • Applies to Single Family and Multi-Family Up to 3

Stories • Does Not Allow Natural Ventilation in Most Climates GOOD PRACTICE: Don’t Rely on Natural Ventilation!

Centralized vs. Unit Level Ventilation

Unit Level Ventilation • Less Maintenance for Building Owner • Can Be Cheaper • Can Help to Avoid Stack Effect Issues Centralized Ventilation • Multi-Family Economy-of-Scale Allows for

Better Heat Recovery / Dehumidification Equipment

• Can Provide Better Energy Performance and Building Humidity Control

• Increased First Cost

Integrated vs. Dedicated Ventilation

Integrated Ventilation • Ventilation System Integrated with Unit HVAC • Requires System Fan to Operate to Ventilate • Dehumidification is Done by HVAC Unit

Integrated vs. Dedicated Ventilation

Dedicated Ventilation • Independent System for Ventilation • Does Not Depend on Unit HVAC • Dehumidification Can be Done at the Outdoor Unit

Benefits of Energy Recovery Ventilation

• Reduces Heating and Cooling Loads by 15-30%

• Reduces Heating Energy by 20 – 35%

• Helps to Control Building Humidity

The Crossings at 4th and Preston

BRW Architects

The Crossings at 4th and Preston • Low Income Housing • 60 Unit Single Room Occupancy • 3 Stories + Basement • Mixed Use: R-2, B & A-2 • Earthcraft Award

• Best Multi-Family 2012

The Crossings at 4th and Preston Challenges / Opportunities

1. Small Unit Size • Right Sizing Equipment • Encourages Centralized System

2. Developer Owned • Allows Recoup of Up Front

Investment 3. Low Income Population

• Smoking in Units • Occupied Much of The Time

The Crossings at 4th and Preston Ventilation Strategy

Building: • Dedicated Outside Air Unit • Pressurized Corridors / Building Units: • Intermittent Exhaust Driven

The Crossings at 4th and Preston Ventilation Strategy

Pros: • DOA Unit Controls Building Humidity • Reduced Ductwork Cost • Fresh, Neutral Air Available on Demand Cons: • No Energy Recovery • Good IAQ Relies on Occupant Behavior • Corridor Pressurization Does Not Effectively Prevent Cigarette Smoke Migration

Crescent Square

VIA Design Architects, PC

Crescent Square • Low Income Housing • 80 Unit Single Room Occupancy • 4 Stories • Mixed Use: R-2, B & A-2 • Earthcraft (Pending)

Crescent Square Ventilation Strategy

Building: • Dedicated Outside Air Unit • Energy Recovery Units: • Continuous, Balanced Ventilation & Exhaust Ducted to Each Unit • Intermittent Range Hood Exhaust

Crescent Square Ventilation Strategy

Pros: • ERV + Dehumidification Unit Control Building Humidity • Energy Recovery Saves Energy • Continuous Ventilation to Building Cons: • Increased Cost of Ductwork

Crescent Square Built-Up DOA Unit

Built-up Outdoor Air System with an ERV + Split A/C Unit.

• Cost Effective Outdoor Air Humidity Control

System Testing and Commissioning

• Build it Tight and Ventilate Right! • Building Air Leakage Testing • Duct Leakage Testing

Summary

• Built it Tight and Ventilate Right • Best Ventilation Strategy Varies Based on Building and Unit Size • Continuous Ventilation Preferred • Dedicated Ventilation Has Many Advantages • Air and Duct Sealing Important