Life Cycle Perspective on School Buildings’ Energy Retrofitting

Abstract: The building sector contributes substantial energy consumption and greenhouse gas (GHG) emissions. Energy efficiency is the main driver for the mitigation of climate change. Schools are placed with high energy consumption and GHG emitting. Most of the existing schools in Europe and Sweden need to be renovated by considering the environmental impacts and energy consumption. Most of the traditional retrofitting techniques have not been evaluated for environmental impacts as well as energy-saving. The project aims to conduct an environmental impact assessment for energy retrofitting options for the school building. Energy simulation and life cycle assessment (LCA) techniques are employed to achieve this target. IDA-ICE and SimaPro programs are used to simulate the retrofitting methods. Celsius high school in Uppsala is selected as a model to study LCA for retrofitting solutions. The retrofitting techniques are focused on three aspects, the demand-side aspect to reduce energy demand in buildings (thermal insulation and ventilation system operation), the supply-side aspect that uses a renewable energy source (solar photovoltaic), and energy consumption patterns (ventilation and lighting time according to schedule of the school days). Firstly, an energy simulation was conducted by IDA-ICE for retrofitting solutions. Adding insulation materials (Cellulose & Glass wool) to the external walls and roof, changing the ventilation operation, from continuous to variable air volume, and installation of photovoltaic panels (PV), caused the energy to be reduced from 142 kWh/m2 to 97 kWh/ m2, with efficiency 32 percent. By the retrofitting methods, the district heating energy is decreased from 87.3 kWh/m2 to 68.8 kWh/m2 and electrical energy is reduced from 54.2 kWh/m2 to 27.8 kWh/m2. Installation of PV on the roof by this area (161 m2) can be produced electrical energy of about 1.5 kWh/m2. Secondly, is conducted life cycle assessment (LCA) for all the proposed retrofitting solutions by the SimaPro program. The system boundary included manufacturing and operation (cradle to operation) and demolition and end-of-life phase are excluded from the system boundary. Functional unit is the operation of the building during during 40 years at Celsius school in Uppsala. The assumption is the retrofitting materials are produced and transport in Sweden. Vattenfall is the supplier of the electrical and heating energy for Celsius school in Uppsala. The most percent of primary energy are waste solid. LCA is presented the retrofitting is decreased the GHG and some of the environmental impact categories.