King County Aquatic Center: Air Quality and Energy Upgrades


The King County Aquatic Center is a large indoor facility that frequently hosts regional and national swimming events.  The facility was originally constructed for the 1990 Goodwill Games.  Over a number of years, the facility had been reducing energy use through operational scheduling changes.  However, concerns over air quality at other large aquatics centers across the country led to close examination of the air exchanges being provided at the facility. 


Measurements resulted in the realization that the facility was at times not capable of providing sufficient air exchanges to ensure healthy air quality.   A significant percentage of the energy savings achieved since 2011 were the result of reduced air flow, and the air quality in the facility was being compromised.  It was also determined that the facility’s peak airflow could not provide sufficient fresh air during large swimming events, which often bring thousands of people into the facility at one time.

The agency in charge of the pool decided it was necessary to add additional ventilation capacity for large events to increase air flow and improve indoor air quality.  During project design, there was an intervention with planning staff to make sure that “fixing” the air quality issues would not come at the expense of energy efficiency.  Management agreed that the design needed to incorporate energy efficiency.  The refined design solution to the air quality problem was a comprehensive project to significantly improve air quality and upgrade equipment in the facility, while integrating the most efficient technologies available.   During final project scoping, the project was also awarded a $500,000 energy efficiency grant from the State of Washington.  This money allowed for the replacement of boiler and heating system equipment that were not part of the initial scope of just addressing the air quality concerns.



A prioritization process looked at the energy use and costs of different options for fixing the air quality concerns. The following measures were identified for implementation during the building retrofit:

  • New condensing boilers: 4,793 therms of savings
  • Heat recovery, natatorium: 529,925 kWh and 31,015 therms of savings
  • Removal of electric resistance heaters
  • Banquet hall HVAC: 34,332 kWh of savings
  • Locker room HVAC: 225,476 kWh of savings
  • Energy efficient lighting, including LED lighting for both interior and exterior applications: 132,529 kWh
  • Solar photovoltaic system: 100 kW

The Aquatic Center has a complicated mechanical system that makes use of condensing boilers, “PoolPak” dehumidification systems, and heat recovery.   Designing the flow of air across the pool surface to minimize chloramines (chlorine byproducts) was a critical consideration during project design.   It has been a challenge to properly balance the efficiency and performance of the different pieces of mechanical equipment while providing the healthiest swimming environment.  The systems in the building are being continually examined to optimize performance, air quality and energy use.   As of late 2015, the facility is undergoing phase two of lighting retrofit activity, which will replace the majority of the lighting throughout the facility with LED fixtures.



Swimmers at the facility have been incredibly happy with the air quality improvements, with many people going out of their way to communicate how pleased they are with pool management.Lighting levels have also been greatly improved in the recreation pool area following installation of the new LED lights.The project is estimated to reduce greenhouse gas emissions by over 550 metric tons each year.


Annual Energy Use

(Source EUI)
Baseline (2011)
695 kBtu/sq. ft.
Actual (2015)
530 kBtu/sq. ft.

Energy Savings:


Annual Energy Cost

Baseline (2011)
Actual (2015)

Cost Savings:


Sector Type

Local Government


Federal Way, Washington

Project Size

81,000 Square Feet

Financial Overview

$3 million

KCAC Boilers
KCAC Boilers

Large Swim Event at KCAC
Large Swim Event at KCAC

Divers at KCAC
Divers at KCAC