Balancing daylight and overheating in low-energy design using CIBSE improved weather files

Abstract

A new set of CIBSE weather files for building performance simulation was recently developed to address the need for better quality solar data. These are essential for most building performance simulation applications, particularly for daylighting studies and low-energy building design, which requires detailed irradiation data for passive solar design and overheating risk analysis. The reliability of weather data becomes paramount when building performance is pushed to its limits. Findings illustrate how principles of good window design can be applied to a case study building, built to the Passivhaus standard, and how its expected performance is affected by the quality of solar irradiation data. Analyses using test reference years were most affected by changes in the solar radiation model (up to 8.3% points), whereas for design summer years the maximum difference was 1.7% points. Adopting the new model caused overheating risk to be classified as more severe using test reference years than design summer years, prompting a discussion on the design summer year selection method. Irradiance data measured on-site were used as a benchmark to evaluate the new solar radiation model, which was found to significantly improve the accuracy of irradiance data within weather files and so the reliability of overheating assessments. Practical application: CIBSE weather files are widely used for compliance verification of building performance in the UK context. This paper tests how the introduction of a new solar radiation model in weather files will affect daylighting and overheating simulation results. Examples are given on how low-energy building design considerations driven by advanced simulation techniques can help reaching indoor visual and thermal comfort requirements.

The importance of infiltration pathways in assessing and modelling overheating risks in multi-residential buildings

“…Wider consideration in this respect needs to be given to ensure that appropriate climate data are used to capture the both the immediate the local context 6,15,16 as well as the long-term temporal context of the building. 17 In the flat monitored, the assumption that infiltration was from the internal corridor through the flat to the outside produced a better overall fit to the monitored data. In terms of the corridors: scenario 1 (AFN) under-predicts the indoor air temperature, whilst the base case and scenario 2 overestimate the corridor air temperature.…”

A Comparison of the Use of Traditional Glazing and a Novel Concentrated Photovoltaic Glazing (Copvg) for Building Solar Gain Analysis Using Iesve

“…The balance between daylighting and overheating is crucial when determining the the correct balance of acceptable gain. Brembilla et al (2020) investigated this balance in low-energy building design, comparing different levels of solar radiation in models to predict daylighting and overheating with different shading components.…”

Experimental Study of Window Shading Effect on Building Thermal-Visual Comfort in a Tropical Region

“…Daylight for conventional residential building is usually obtained through windows or glass doors installed on the wall [30]. However, direct solar radiation that enters through the transparent surface of the window can cause an increase in the indoor air temperature [31]. Therefore, implementing a strategy to regulate solar radiation to obtain maximum lighting with minimal overheating impact is necessary.…”