Influence of Climate Change on Building Effluent Wastewater Temperature in Stockholm by 2040

Abstract: This report aims to give predictions of Stockholm’s region climate (especially temperature and precipitations) by 2040 and describe the consequences of possible climate changes on the building effluent water temperature and flowrate. First, I did an extensive review of the literature about climate change and climate prediction in Stockholm’s area in order to suggest probable climate scenarios for 2040, using climatic data from the reference period 1960-1990. Then the method of Heating and Cooling Degree Days was used to evaluate the consequences of climate change on household habits, and thus on building effluent water characteristics. It appears that Stockholm’s climate in 2040 will be different than in 1960-1990 with a really high probability. The most probable scenario indicates moderate warming (+1.5°C annually) and an increase in precipitations (+5% annually), with a strong seasonal heterogeneity: most warming and increase in precipitations happens during winter, while summer should become dryer. The climate is also predicted to become more variable, with increased extreme events. These changes have an impact on household habits: heating demand should decrease (by approximately 12% in a moderate warming scenario), and cooling demand increase remarkably (by more than 100% even in a moderate warming scenario). Thus, building effluent water temperature will decrease significantly (about 1°C to 2°C depending on the climate scenario), mostly due to the decrease in household heating.