3 Integrated Model Nada Tarkhan and Sam Wolk Our model consists of two components, a simulation engine to calculate a large combination of technology pathways for the campus and an interactive dashboard that allows a general audience to browse the pathways and form their own opinion. Engine A simulation engine has been developed with two main steps, building load calculations and energy supply modeling. Building load calculations are executed via the US Department of Energy’s EnergyPlus whole building simulation engine. EnergyPlus is a validated, physics-based simulation to solve heat and mass flow rates in buildings (NREL 2024). The campus model of building loads is a bottom-up portfolio model, developed with urban building energy modelling (UBEM) methods, as in (Reinhart et al. 2016; Ang et al. 2022), and informed by previous work by (Nagpal, Hanson, and Reinhart 2019). EnergyPlus is used to model individual building hourly loads for heating, cooling, hot water, and electricity, informed by building characteristics, and future weather files (see section on Future Grid Emissions and Climate). Each building of interest (buildings owned and operated by MIT), is modeled as a series of 4 representative “shoeboxes,” which serve as a simplification of building geometry for rapid portfolio modeling, while maintaining geometric and solar context. Building parameters are based on calibrated findings from (Nagpal, Hanson, and Reinhart 2019), with individual definitions of building construction. Internal loads are defined based on program, with “templates” defined for circulation/support, residential, classroom/office, and lab space. In the various demand-reduction pathways, envelope retrofits, building controls, and lab retrofits are all modeled as transformations of the underlying EnergyPlus IDF models for each building. Each building is scheduled for renovation according to a sequence which completes all buildings by 2050. Hourly demands for each year are determined by selecting the appropriate result for each building according to its upgrade state, the appropriate year, and climate scenario. By default, all buildings are connected to the combined heat and power (CHP) central utility plant (“the CUP”). In scenarios including development of a new district heating and cooling network, buildings are scheduled for disconnection from the existing CUP network to the new network between 2030 and 2040. The existing CUP network is assumed to have distribution losses of 50% while the new high-temperature district network (“partial” scenario) is assumed to have distribution losses of 10%. Campus electricity demand is first supplied by any carbon-free generation capacity (photovoltaics, nuclear microreactors, and deep geothermal) if available in the specified scenario. Then, a simplified model of the CUP’s equipment (gas turbines, heat recovery steam generators, steamdriven chillers, and electric chillers) is operated at each timestep to meet the total electricity and thermal demands on the CUP, yielding total gas demand with excess electricity imported from the grid when applicable. This model is configured from simple efficiencies and capacities of
RkJQdWJsaXNoZXIy MjA2MzQ5MA==