Introduction

The newly remodeled Willamalane Aquatic Center in Springfield, Oregon is an ideal laboratory for studying the role of a large quantity of thermal mass in a conditioned airspace. The design intention is that the HVAC system will provide complete control over the interior environment. According to the project architect’s design experience, thermal transfer through the building envelope contributes just 15% to the total energy costs for operating the pool. For this reason, less consideration was given to glazing, solar exposure, and solar gains. Our case study explores the degree to which insolation affects the indoor air temperature of a pool building, and has some potential to influence design decisions regarding solar gains in pool buildings.

Abstract

Measurement of indoor air temperatures at an indoor pool facility provides a platform for exploring the relationship between indoor climate and external conditions such as outdoor temperature and solar gain. The Willamalane Aquatic Center located in Springfield, Oregon has all the conditions (and more) necessary for such a study: multiple pools maintained at three different temperatures, four zones of HVAC covering the main pool area, and a variety of enclosure treatments, including ample east-side glazing. Temperature readings were collected over a period of two weeks in November 2000, yielding two data sets, each spanning three full days.

This report offers the hypothesis that indoor air temperature readings would show negligible changes during a diurnal cycle. This is not supported by study findings, which in fact show a significant indoor temperature gain on clear days, attributable to solar gain. Willamalane's HVAC system and maintenance schedule also impact the indoor temperature on a daily basis. Aside from these conclusions, the study addresses one question that could not be answered: is it the thermally massive pool water or is it the HVAC controlled air temperature that is a driving force behind the climate of an indoor pool?