Overview This element investigates and demonstrates the application of building science and ventilation engineering to produce simultaneous savings in building energy use and improvements in indoor environmental quality. The work focuses on developing and testing a concept for high-performance relocatable classrooms (RCs). Commonly known as "school portables" or "modular classrooms," RCs are frequently used in California as a quick and convenient means of adding or replacing classrooms. RCs can be moved, reducing unnecessary classroom construction. Currently, the state of California mandates that at least 20 percent of new classrooms be RCs.

Technical Highlights

We have set out to evaluate the benefits of a novel building ventilation system and of construction materials that emit fewer indoor pollutants than is currently typical. We are currently building four RCs that we will study in pairs at two elementary schools, each in a different California school district and different climate zone. We have selected a high-performance ventilation and air conditioning system, the Indirect-Direct Evaporative Cooler (IDEC) that is suitable for warm, dry California climate zones. In these climates, IDEC could save about 70 percent of the cooling energy used by the standard 10-Seasonal Energy-Efficiency Rating (SEER) air conditioner that is typical in RCs. In addition to saving energy, the IDEC provides a continuous flow of outside air, which improves indoor air quality relative to traditional ventilation strategies. The IDEC only provides cooling, however, so we have recently completed design and testing of a prototype high-efficiency gas-hydronic heating system that is incorporated into the IDEC air distribution system.

Our study includes comparison of the energy use, ventilation performance, thermal comfort, and indoor environmental quality of the IDEC/hydronic system against a standard 10-SEER, wall-mounted heating, ventilation, and air conditioning (HVAC) system. We are constructing the test RCs so that they will have both the IDEC and a conventional electric-compressor-based air conditioner/heat pump installed; this is a case-crossover design where each RC serves as its own control. During the next school year, we will alternately operate each system weekly for 8-10 weeks during the cooling and heating seasons and compare the energy use and indoor environmental conditions during the alternate weeks of operation.

Computer simulations of energy use with the conventional RC versus the high-performance RC have been developed for a range of California climate zones. These simulations will be refined at a later phase of the study using the data on system performance collected from RCs in the field.

A second research area focuses on the selection of building materials. Adequate building ventilation helps ensure that volatile organic compound (VOC) concentrations do not build up in classrooms. The choice of materials and construction techniques, however, can make a significant difference in the amounts and types of VOCs emitted. Some VOCs are known to be odorous or irritating to the respiratory system, eyes, nose, and throat and have been associated with health symptoms in building studies. Working with an RC manufacturer, we have evaluated and tested specific categories of interior construction materials used in conventional RCs to identify significant VOC sources. We have found alternative low-VOC-emitting materials or materials-sealing techniques to reduce the release of these gases. We have specified replacement of selected materials with those tested and found to have lower emission rates of potentially toxic or irritating VOCs. One of each pair of RCs to be located at each participating school district's elementary school is being constructed using the substituted materials. During the upcoming field investigation, we will take VOC measurements on one school day per week throughout the study period to compare the VOC levels in the low-VOC RCs with those in the standard units as well as to the predicted concentrations from empirical emission factors determined by laboratory environmental chamber conditioning and testing.

• High-Performance Modular Classrooms (588 KB, 2 pp)
   

The purpose of the Energy Simulations and Projected Statewide Energy Savings project is to develop reasonable energy performance and cost models for high-performance RCs across California climates. This project is broken into an initial and a final phase.

Tasks:

The role of this project is to conduct energy and indoor environmental quality studies on high- performance RCs in California.

Tasks:

Contact: Michael Apte, Lawrence Berkeley National Laboratory (LBNL), (510) 486-4669