LCC comparison between centralized- and decentralized mechanical ventilation

Purpose: The forthcoming energy requirements that will come into force in 2020, are about more energy-efficient construction and strive to build near-zero energy buildings. In order for the building industry to succeed in producing buildings that meet these demands, it requires more energy-efficient products and installations within the framework of a normal investment. It is the operating cost that is responsible for the largest energy use in buildings, which opens to investigate the energy consumption over a life cycle cost. Choosing the right ventilation system reduces the energy consumption, and then the life cycle cost if the investment makes too much impact. It is generally known in the building industry that the design- and production times are very time limited, which means that companies use previously proven systems that work regardless of whether there are more energy-efficient products. This can lead to reduce the innovative thinking for sustainable development, so that better options for installations do not find out in the global market. The study refers to comparing the two different ventilation systems centralized and decentralized in terms of energy and life cycle costs. To make a decision which of the centralized- and decentralized system is the better option. Method: For the most part, the quantitative method of collecting and analyzing quantifiable data is applied. Document analyzes and own calculations have given rise to the result. Findings: The study´s results indicate that the decentralized ventilation system is both more energy efficient and has less cost over a life cycle. One major reason for the result is the sale of the extra living space that occurs when vertical shafts disappears when installing decentralized ventilation system. It can also be seen in the result that the air unit is cheaper for the centralized ventilation system, while installation and materials are cheaper for the decentralized ventilation system. Implications: As the result shows, the decentralized ventilation system is both more energy efficient and cheaper over a life cycle. Additional energy savings on the decentralized ventilation system can be done if a home-away mode is installed. It means that the airflow decreases when no one is home, which reduces energy consumption. Furthermore, it will be ensured that removal of vertical shaft when installing decentralized ventilation system reduces investment and more saving can be done. Limitations: This study will only analyse a five-storey multifamily house in Jönköping together whit a centralized and decentralized ventilation system. Keywords: Ventilation, HVAC, centralized mechanical ventilation, decentralized mechanical ventilation, Nzeb, LCC