Monday, 5 September 2016

The Importance of Energy Modelling

In a recent article published by our energy expert Eoghan Hayes, he outlines how plug and lighting energy can have a major impact on building energy use.

In high-rise residential or multi-unit residential building, appliance plug and lighting energy account for 20%-25% of total energy use in the building. Eoghan explains that ‘the by-product of their electrical consumption of heat, which helps heat the suite in winter but becomes a hindrance during the summer, when we want to keep the suite cool.’  Over estimating in these energy modelling simulations can reduce heating energy and increase cooling, while underestimating them will do the opposite.

The article compared four different standards of energy modelling, analyzing the impact of underestimating and overestimating plug and lighting load power densities and schedules. ASHRAE 90.1-1-2007, LEED for Homes, Measured Utility Data, and BC Hydro New Construction Program Energy Modelling Guideline were used to compare the different methods and schedules used to simulate plug and lighting loads in residential buildings. While ASHRAE 90.1-2007 is the most common standard for lighting and plug standards, the LEED for Homes rating system is the most comprehensive for residential situations.

The LEED for Homes appliance calculator is used to calculate the annual energy usage per appliance. In the LEED rating system, points are rewarded for energy savings from appliance energy whereas most ratings systems do not. LEED for Homes requires Energy Star ratings for appliances. This usually accounts for upwards of 8% energy improvement from the baseline.

The results from all four standards ranged from 50.97 kWh/m2/year with Measured Utility Data to 56.16 kWh/m2/year with the BC Hydro guideline. The results indicate that 53.5 kWh/m/2year (+/-5%) would be an appropriate specification for lighting and plug power densities and schedules.

The article outlines how municipalities should state the appropriate energy density to ‘ensure consistency among energy models submitted for code and LEED compliance and prevent mistakes from submitted simulations’.

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