Design and Assessment of District Heating Systems with Solar Thermal Prosumers and Thermal Storage

In this study, a holistic energy, economic and environmental assessment was performed on a prosumer-based district heating system, including scenarios with varying district size, retrofitting stages and system configurations. A modeling framework was built which comprises a thermal network design and simulation model; a building energy demand model for districts; and supply and storage technology models that allow assessing system solar fraction, equivalent annual cost and greenhouse gas emissions of district heating systems (DHS). Furthermore, the approach allows comparing the performance of a DHS with individual heating systems (IHS) for the district with the same set of technology options (rooftop-mounted solar thermal collectors, gas boilers and thermal storage tanks). The framework was applied to a Swiss case study. The results of the case study show that DHS often outperform IHS; however, parameters such as the district size, the retrofitting stage of buildings and the system configuration have impacts on the performance of the DHS. The most important parameter lies in the adequate selection of the storage volume over solar collector area ratio, which indicates that DHS solutions are only advantageous if they are properly sized. Smaller districts and districts with retrofitted buildings especially benefit from DHS solutions in terms of energy, economic and environmental performance. Maximum solar fractions of 50% (non-retrofitted case) and 63% (retrofitted case) were reached with the DHS solutions.

Relationships between District Size, Socioeconomics, Expenditures, and Student Achievement in Washington

The purpose of this article is to describe the relationship between district size, socioeconomic status, actual levy percentages, and their predictive influence on the 2003 Washington Assessment of Student Learning results for 4th and 7thgrade students in Reading and Mathematics. The convenient sample was 82 Washington State 2nd-Class school districts with enrollments between 500-2,000 students. The results indicated: (a) no significant correlations between achievement anddistrict size; (b) socioeconomic status was the best predictor of achievement; and (c) actual levy percentages and student outcomes were significantly correlated in the positive direction.

Subnational Patterns of Participation: Compulsory Voting and the Conditional Impact of Institutional Design

Cross-national studies of turnout find that compulsory voting has the strongest impact on participation, boosting turnout by 10 to 18 percent. We argue that in the absence of compulsory voting, other institutional factors such as small district size, strong electoral competition, and moderate candidate fragmentation may be similarly effective at mobilizing turnout. Where voting is mandatory, these factors should instead primarily influence how people vote once they are at the polls—diminishing levels of invalid voting, and consequently increasing effective turnout. We take advantage of the abolition of compulsory voting in Chile to test our expectations immediately before and after reform, in the exact same electoral districts. Using this unique subnational research design, we leverage data from more than 1,000 mayoral elections over the course of three electoral cycles and across 345 municipalities to examine patterns of turnout and invalid voting. Results show that small district size, strong electoral competition, and moderate candidate fragmentation are effective at reducing invalid voting when turnout is compulsory, and fostering higher levels of turnout when voting is voluntary.

It is in the Contract: How the Policies Set in Teachers’ Unions’ Collective Bargaining Agreements Vary Across States and Districts

We examine more than 1,000 collective bargaining agreements (CBAs) in place across California, Michigan, and Washington. We investigate the prevalence of a set of 43 key provisions between and within these states, providing the first comprehensive comparison of CBA terms using data drawn from economically and demographically different districts, as well as districts that vary considerably by student enrollment. We find that CBAs vary substantially within and across states, and that this variation is more associated with district size than the proportion of low-income students within districts. We conclude by discussing the implications of these findings for research and policy.