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ABSTRACT
A common criticism of the Nationwide House Energy Rating Scheme (NatHERS) is the adequacy of the thermal assessment software second generation AccuRate. Many argue that the software is not capable of accurately modelling the building envelope and therefore should not be used as a tool in mandatory regulation. In the ‘Rating’ mode of operation AccuRate has limited capabilities in terms of input and output due to its regulatory nature. However, at the heart of AccuRate is the computational engine Chenath, an hourly simulation engine which has been tested and validated. This paper presents a comparison of simulations of buildings with massive construction elements using Chenath (V2.26), EnergyPlus (with DesignBuilder as the user interface), and Ener-Win. The comparisons were conducted for 1) a hypothetical test cell 2) a constructed test cell, and 3) an occupied house, where the simulation results were also compared with measured data. The results show that simulations with Chenath using AccuRate as the interface, compare favourably with the other two simulation engines and measured data with acceptable CV(RMSE).

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