Energy retrofit and conservation of a historic building using multi-objective optimization and an analytic hierarchy process

When deciding on the best historic building retrofit,energy savings and thermal comfort can be quantitatively evaluated using an energy model,whereas conservation compatibility is intrinsically qualitative and reflects the perspective of the local heritage authority. We present a methodology that permits finding and comparing optimal retrofits for historic buildings in a multi-perspective and quantitative way. We use an analytic hierarchyprocess to quantify conservation compatibility by distilling a conservation score from the opinions of 10 experts in the field. This score,along with energy needs for heating and cooling and thermal comfort,are the three targets of a multi-objective optimization aimed at identifying optimal retrofits for a medieval building in the north of Italy,destined to become a museum. Retrofit measures considered were different kinds of external and internal envelope insulation,improvement of airtightness,replacement of windows,and ventilative cooling. The result is a portfolio of optimal retrofits that cover the whole range of conservation compatibility. We showthat in the analyzed case heritage preservation is compatible with a four-fold reduction in energy needs at a high thermal comfort level. Even higher energy savings are only achievable at the cost of heritage degradation.

Advancing and demonstrating the Impact Indices method to screen the sensitivity of building energy use to occupant behaviour

A critical gap between the occupant behaviour research field and the building engineering practice limits the integration of occupant-centric strategies into simulation-aided building design and operation.Closing this gap would contribute to the implementation of strategies that improve the occupants’well-being while reducing the buildings’environmental footprint.In this view,it is urgent to develop guidelines,standardised methods,and supporting tools that facilitate the integration of advanced occupant behaviour models into the simulation studies.One important step that needs to be fully integrated into the simulation workflow is the identification of influential and non-influential occupant behaviour aspects for a given simulation problem.Accordingly,this article advances and demonstrates the application of the Impact Indices method,a fast and efficient method for screening the potential impact of occupant behaviour on the heating and cooling demand.Specifically,the method now allows the calculation of Impact Indices quantifying the sensitivity of building energy use to occupancy,lighting use,plug-load appliances use,and blind operation at any spatial and temporal resolution.Hence,users can apply it in more detailed heating and cooling scenarios without losing information.Furthermore,they can identify which components in building design and operation require more sophisticated occupant behaviour models.An office building is used as a real case study to illustrate the application of the method and asses its performance against a one-factor-at-a-time sensitivity analysis.The Impact Indices method indicates that occupancy,lighting use and plug-load appliances have the greatest impact on the annual cooling demand of the studied office building;blind operation is influential only in the west and south façades of the building.Finally,potential applications of the method in building design and operation practice are discussed.