Office Refurbishment - Operational Energy Modelling and M&V


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IES Consulting and the new iSCAN tool played a pivotal role in ensuring the client’s sustainability aspirations were met by using cutting edge operational energy modelling, and M&V techniques to assess and ensure energy performance targets were met at design, construction and operation.

Key Facts

  • LEED Gold Certified
  • Predicted energy saving of 63%
  • Energy modelling used from design, to operation, and for M&V
  • Actual building brought to within 8% of its predicted energy performance

IES Consulting was engaged on this high-end refurbishment project in Dublin, Ireland, across the whole design-build-operate cycle. Undertaking innovative energy modelling which encompassed ‘what if’ testing of retrofit options, LEED Certification and post occupancy Measurement & Verification (M&V) that predicted energy savings were being achieved.

At design the project achieved LEED Gold with a predicted 63% energy saving over the baseline. To ensure this predicted performance was achieved post occupancy, the client used M&V as a way to verify the expected cost and energy savings were actually seen, and that the expected return on investment would be achieved within the predicted period.

The client opted to use the International Performance Measurement and Verification Protocol (IPMVP) Option D, Calibrated Simulation as the method of Measurement and Verification (M&V).

IPMVP Option D involves the detailed model calibration of the LEED energy model to align with actual as-built operational conditions including the update of HVAC system operational times, occupancy patterns, real weather data, equipment and lighting loads. The performance of the actual building is then assessed against this operational calibrated model.

In order to undertake this, IES first uploaded to our cloud-based tool iSCAN, all the data relating to the energy performance of the building that was being logged by the Building Management System (BMS) and Utility meters. IES then performed a comprehensive data audit and forensic interrogation of the data using iSCAN to assess the impact of the energy efficiency measures. This was before connecting the data to the IES Virtual Environment IESVE) software for model calibration.

At this stage, a number of energy affecting issues/inefficiencies within the building’s HVAC plant were identified and fixed on-site leading to impressive measured energy savings of; 25% in cooling energy, 18% in heating energy and 13% in fan and pump energy.

The detailed energy model was then successfully calibrated with a 1.0% variation (Mean Bias Error-MBE) between the actual building metered energy and the model energy usage. Results of the calibration showed a reduction in predicted total building energy savings from design stage at 63% to 55% at post construction stage.

By identifying and working with the client to address the energy inefficiencies discovered within the building in operation, IES was able to attribute gap to the following key differences between how the building was built over how it was designed:

  • No insulation on ground floor slab
  • Building negatively pressurised in the order of 21% (leading to higher infiltration rates)
  • 30% reduction in internal heat gain
  • Higher process energy loading in data center, UPS and comms rooms
  • HVAC distribution losses excluded in design stage models as required by ASHRAE 90.1 have been included in the calibrated energy model.

Following the calibration process, additional opportunities for energy savings were found and recommendation made to the client on how to further improve building performance.

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