Assessment of Retrofit Measures for Industrial Halls: Energy Efficiency and Renovation Budget Estimation

The need for renovation is driven mostly by high energy prices and by the amortization of building envelope structures and building systems. Industrial buildings built before 1990s are usually poorly insulated and without ventilation heat recovery. When renovation is considered, it raises a question of what and to which extent to renovate, to achieve the optimal result for the investment. The current study focuses on the building envelope insulation and ventilation renovation options for hall-type industrial buildings. We have analyzed the impact of different renovation measures, regarding envelope insulation and ventilation systems, to the energy consumption and renovation budget for three typical buildings built between the 1960s and 1990s in Finland. The energy consumption calculations have been conducted with building energy and indoor climate simulation tool IDA-ICE. For the economic calculations, we have used the current Finnish energy prices and interest rates with moderate trends for the next 20 years to estimate the internal rate of return and net present value of the retrofit measures. The calculations have been done for two building sizes: a large hall, 137m x 66m, and for a smaller hall, 40m x 22m, both with an average height of 8m. The results show, that retrofitting the building envelope only for energy efficiency might not be beneficial when considering a payback period less than 20 years in the case of both large and small hall buildings. In case of smaller halls, some combinations of envelope retrofit can be also economically reasonable. Renovating the ventilation system by applying heat recovery and replacing lighting for energy efficient LEDs would be beneficial for all the initial building cases. Combination of supporting measures as a renovation package would be the most recommendable solution.