Comparative energy and cost assessment of Vacuum Insulation Panels (VIPs) for energy retrofitting of office buildings in different climatic conditions

Improving energy performance of existing buildings can be challenging, particularly when facades cannot be modified, and the only available option is to apply internal insulation. In such cases, the choice of the most suitable material becomes increasingly complex, as in addition to energy consumption, capital cost, practicality and maintenance, the designer needs to account for the impact of the intervention on the internal usable space. This paper compares the energy and cost assessment of applying Vacuum Insulation Panels (VIPs) and different traditional thermal insulation materials to a typical 1980’s multi-storey office building requiring retrofit to meet the current building regulation standards. The building is simulated through dynamic performance simulation under three different climate conditions (London, Toronto, Madrid) in order to evaluate its annual energy needs. Energy simulations has shown that application of thermal insulation has reduced heating energy consumption in case study building by 14.6%, 9.7%, 20.1% for London, Toronto and Madrid respectively compared to pre-retrofitting. The payback period evaluation was based on the Net Present Value method and additionally considering the potential rental value of space saved due to comparatively less thickness required by VIP insulation. Results have shown for traditional insulation materials the payback periods were longer than 10 years considering capital cost and energy savings which may not be economically feasible for such type of building retrofitting. However, when accounting for the value of space saved by applying VIP insulation in case study buildings, the payback periods can be reduced to 1.8, 3.5 and 4 years for London, Toronto and Madrid respectively making the retrofitting more economical. This study shows that by considering the space saving value even at the current capital costs, VIPs raise to be the most financially appealing material to be used in multi-storey office buildings wherever the value of the internal space is above a certain threshold.