Modelling LCC for Different Indoor Climate Systems

Sammanfattning: The indoor climate system, which serves a building with a proper indoor air quality and thermal comfort, has been predominantly designed based on the initial investment costs. A life cycle approach could improve both the economic and environmental performance since the energy use would decrease. Currently, there is a lack of knowledge, models and tools for determining the life cycle cost (LCC) for an indoor climate system. The objective of the ongoing research project is to develop a model and tool for choosing indoor climate systems based on the lowest LCC. The objectives of this licentiate dissertation are to report on the-state-of-the-art, discuss and determine the methods to use in the research project, give some examples of LCC analyses on indoor climate systems, discuss different control strategies for indoor climate systems, analyse optimal supply air temperature as a control strategy to lower the energy use and to define and discuss what will be included and excluded in the LCC model. Life cycle costing is a technique where future costs are discounted to the net present value for the entire life span. Problems are to define the life span, the boundary to determine whether to include a cost or not and find interest and price change rates. Even though a number of parameters are not known, it should be better to perform analyses than use investment cost only. The most common indoor climate systems in Sweden will primarily be included. Results show that proper controlling can decrease the energy use, influence on work performance from the indoor climate can be highly decisive and residential buildings may not be forgotten in the LCC model, since a lot of energy can be saved. Risks will be handled by sensitivity analyses on deliberately changeable parameters and Monte Carlo calculations for the parameters with known statistical distributions. The tool must be easy to use for clients and manufacturer of indoor climate systems and as much input data as possible must be generated automatically. The future work will fill the model with calculation methods for a number of costs and create the tool and use it on practical examples to obtain guidelines for good indoor climate systems with regard to low LCC.