Roof–envelope ratio impact on green roof energy performance

This paper addresses the impact of roof-to-envelope ratio on overall energy savings of a green roof design over conventional roof designs. Simulations were performed using a modified version of the Environmental System Performance program simulator, developed at the University of Strathclyde. The modified design employed a model developed by Columbia University and the Goddard Institute of Space Science which models the evapotranspiritive effect of a green roof calculated using the Bowen ratio; that is, the ratio of sensible heat flux to the surrounding air to the latent heat flux resulting from evapourative energy losses. The resulting heat flux term is proportional to the external surface convection, but inversely proportional to the surface Bowen ratio, which is held constant and chosen to match experimental results obtained for a given roof design. The present study performed simulations for the month of July in a Toronto climate on square warehouse style one, two, and three-story buildings, with windows occupying 10% of the area of each wall. For the first set of simulations, the internal building load of each story was set to zero, and the roof–envelope ratio was increased by increasing the building width and length. For the final simulations, several roof–envelope ratios were chosen, and the internal load of each story was increased from 0 to 50,000 W. As the roof–envelope ratio increases, the cooling load of the upper floor for multi-story designs approaches the entire building cooling load. This indicates the importance of upper zone cooling in total building energy reductions. Furthermore, the total energy savings of a green-roofed building over a conventional roofed building were far more significant for single-story structures. A 250 × 250 m green-roof design with 50,000 W internal loading was found to have percentage energy savings of 73%, 29%, and 18%, for a one, two, and three-story design, respectively.     

Psychotropic medication management for youth in state care: consent, oversight, and policy considerations

The use of psychotropic medications in youth with emotional disturbances in state custody is increasing and presents unique challenges concerning consent and oversight. We examine various means that state child welfare agencies use to provide consent for and oversight of psychotropic medications for children in state custody and describe benefits of a consent process that provides for expert consultation to the child welfare agency and prescribing clinicians, case-specific and systemic oversight of psychotropic medication use, and education for stakeholders.     

Influence of yard work and weight training on bone mineral density among older U.S. women

The purpose of this study was to determine the influence of type of physical activity on bone mineral density among older U.S. women. Findings from the present study indicate that jogging, swimming and calisthenics were weak predictors for high bone density values. Bicycling, aerobics, walking and dancing were moderate predictors for positive bone density. Yard work and weight training were strong and independent predictors for positive bone density.     

Estimates of air pollution mitigation with green plants and green roofs using the UFORE model

The purpose of this study was to investigate the effect of green roofs and green walls on air pollution in urban Toronto. The research looked at the synergistic effects on air pollution mitigation of different combinations of vegetation by manipulating quantities of trees, shrubs, green roofs and green walls in the study area. The effects of these manipulations were simulated with the Urban Forest Effects (UFORE) model developed by the USDA Forest Service Northeastern Regional Station. While UFORE contains several modules, Module—D quantifies the levels of air pollution for contaminants such as NO₂, S0₂, CO, PM₁₀ and ozone as well as hourly pollution removal rates and the economic value of pollutant removal. Six vegetation scenarios were developed within the Toronto study area to compare different subsets of vegetation and their effect on air contaminants. Results of the study indicate that grass on roofs (extensive green roofs) could augment the effect of trees and shrubs in air pollution mitigation, placing shrubs on a roof (intensive green roofs) would have a more significant impact. By extension, a 10–20% increase in the surface area for green roofs on downtown buildings would contribute significantly to the social, financial and environmental health of all citizens.