A luxury development of 6 detached homes in Plymouth
– A plot was planned to be sited close to a stand of 5 mature mixed deciduous and coniferous trees.
– The rear elevation comprising the living areas, study and bedrooms may be influenced by the feature.
– The client required an understanding of the impact of the obstruction on future occupants of the dwelling
– An in depth analysis of the available daylight into the dwelling as designed when in relation to the stand of mature trees was required.
– A Daylight Study was commissioned to offer an understanding of the impact on internal daylight conditions of a stand of mature trees to the Rear of one of the dwellings.
– The Study utilises daylight analysis software and Dynamic Simulation Modelling with RadianceIES and Suncast to illustrate the impact of the various daylight scenarios on the dwelling
Three Daylight analyses methodologies were used to investigate the available light within the building.
- Vertical Sky Component (VSC). VSC measures the amount of unobstructed skylight. the guidance is that if the VSC falls below 27% there is unlikely to be sufficent daylight. If it is above this level, there is potential for acceptable light levels. The CIE Overcast Sky is used to give the worst case scenario (in design terms) for illuminance.
- Shading Study. A simulation taken at 3 times of the day during daylight hours was used to illustrate the shading potential within the dwelling associated with the standing of trees in the rear garden. The simulations time were taken as 9.30am, 12.30pm and 4.30pm. The simulation was made for mid January, and mid July.
- Dynamic Simulation. A simulation of natural light across each room taken at the working plane (0.85m above floor level) for 12 design days through out the year for each room. The daylight is measured as a Daylight Factor.
The results from Visible Sky Componet (VSC), Shading Study and Dynamic Simulation show there are rooms within the unit which will be effected by low daylight levels associated with the tree canopy to the rear of the property.
March -April 2017
Plymouth City Council
Vertical Sky Component (VSC)
The first stage of the investigation is to establish the obstructions to daylight. Initial Dynamic Simulation modelling established the Vertical Sky Component (VSC) which measures the amount of unobstructed skylight through each window opening. BRE guidance suggests that if the VSC falls below 27% there is unlikely to be sufficient daylight in that zone or room. If it is above this level, there is potential for acceptable light levels.
A simulation taken at 3 times of the day during daylight hours was used to illustrate the shading potential within the dwelling associated with the stand of trees in the rear garden.
Dynamic Simulation Results Summary
|Annual Average Daylight Factor for Overcast sky
|300 lux 50% of daylight hours
(% of room)
|Annual Average Lux for overcast sky
|First Floor Study
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