IES Consulting performed energy analysis to document LEED EA Prerequisite Minimum Energy Performance and EA Credit Optimize Energy Performance for this project. To do this they assessed the model through the Performance Rating Method (PRM) of ASHRAE 90.1-2010 Appendix G using IESVE building energy simulation software.
The project is an 11 150 m2 renovated commercial office building located in Guyancourt in the Paris region and is pursuing LEED V4 Certification.
The purpose of the work performed by IES Consulting was to demonstrate the reduction in running costs of the Proposed design in comparison to the ASHRAE 90.1 2010 Baseline model.
The analysis demonstrated the Proposed building achieved a reduction in energy of ~29% and a reduction in running cost of 29%. For ‘Core and Shell’, a cost reduction of 29% would therefore achieve 13 LEED points.
Significant savings were discovered in heating and internal lighting. The significant savings in lighting energy are predominantly due to the significantly lower Lighting Power Densities specified in the Proposed case in comparison to the Baseline. Both the Proposed and Baseline buildings included dimming controls as per ASHRAE 90.1 2010. The significant reduction in the building’s heating demand was achieved through the inclusion of building fabric with U-values significantly lower than used in the Baseline. As a consequence heat lost through the building fabric is less than 50% to that of the Baseline.
In addition, the Proposed case also has reduced ventilation losses since the ventilation is tempered via a heat recovery device. As the minimum outdoor air flow rate is <30% of the design airflow rate the Baseline does not include heat recovery.
The reduction of these loads means that for the majority of the time the heating set point can be achieved through the presence of internal gains only. At times where heating is required in the Proposed it is generated by a heat pump with a high COP. By comparison, heating provided in the Baseline is generated by electrical resistance with a significantly lower efficiency.