incubator2, alconbury weald · design note – solar shading analysis...

Incubator2, Alconbury Weald

Solar Shading Analysis

November 2016


Design Note – Solar Shading Analysis

DN-2601167-08-MV-20161130-Alconbury Incubator 2 Solar Shading Analysis Page 1

Ground Floor Botanic House 100 Hills Road

Cambridge, CB2 1AR

Tel: 01223 556 820 Audit Sheet

Revision Description Date Prepared by Reviewed by

1 Planning issue 30/11/2016 MV TC

This report is provided for the stated purposes and for the sole use of the named Client. It will be confidential to the Client and the client’s professional advisers. Hoare Lea accepts responsibility to the Client alone that the report has been prepared with the skill, care and diligence of a competent engineer, but accepts no responsibility whatsoever to any parties other than the Client. Any such parties rely upon the report at their own risk. Neither the whole nor any part of the report nor reference to it may be included in any published document, circular or statement nor published in any way without Hoare Lea’s written approval of the form and content in which it may appear.




CONTENTS 1 Introduction ...................................................................................................................................... 3

2 Solar Shading Options ..................................................................................................................... 4

2.1 Baseline: Horizontal brise soleil, depth 1800mm ......................................................................... 4 2.2 Option A: Horizontal brise soleil, depth 1000m ............................................................................ 5 2.3 Option B: Vertical brise soleil, length 1000m ............................................................................... 6

3 Sunpath images ................................................................................................................................ 7

4 Conclusions ...................................................................................................................................... 8




1 Introduction A preliminary solar shading analysis has been carried out using IES Virtual Environment to quantify the amount of solar radiation received by the south, east and west facades, assess the effectiveness of the brise-soleil included in the current design and identify the areas where further solar shading should be installed to diminish solar gains and reduce the risk of overheating. As shown in Figure 1, brise-soleil (1800mm deep) has already been incorporated in the design. The drawings were received from Allford Hall Monaghan Morris Architects on 21st of November 2016. Various brise soleil systems have been compared and their performance in terms of reducing solar gains has been evaluated. The following options have been examined:

1. Baseline scenario: Horizontal brise soleil, depth 1800mm. 2. Option A: Horizontal brise soleil, depth 1000m. 3. Option B: Vertical brise soleil, length 1000m.

Figure 1: IES model of Incubator2, Alconbury Weald Building (South facade - baseline scenario)

Figure 2: IES model of Incubator2, Alconbury Weald Building (North facade - baseline scenario)




2 Solar Shading Options

2.1 Baseline: Horizontal brise soleil, depth 1800mm

Simulations were run to quantify the amount of solar radiation received by the south, east and west facades. Figures 3 and 4 show the solar irradiance on the different surfaces of the building in the summer period (1st May to 30th September), when limiting the solar gains is required. As shown, the proposed 1800m m deep brise soleil system considerably reduces the solar irradiance in the top 2 - 2.5m of the south facade. Figure 3 also presents the maximum solar gains, calculated for each floor and office area. The BCO-Guide to Specification 2014 suggests that solar gains in office buildings should fall in the range of 50 - 65 W/m2. As shown below, solar gains do not exceed the maximum recommended value of 65 W/m2 and the following maximum values were calculated:

Office areas Solar gains [kW] Solar gains [W/m2]

Ground floor office 1 ~8.87 53.47

First floor office 1 ~9.94 59.88

Ground floor office 2 ~7.91 47.65

First floor office 2 ~9.42 56.79

Figure 3: Baseline, Solar irradiation on the south facade, (1st May to 30th September)

Figure 4: Baseline, Solar irradiation on the north facade, (1st May to 30th September)

Ground floor office 1, Maximum solar gain:

53.47 W/m²


47.65 W/m²

First floor office 1, Maximum solar gain:

59.88 W/m²


56.79 W/m²

2 - 2.5 m




2.2 Option A: Horizontal brise soleil, depth 1000m

Simulations were run to quantify the amount of solar radiation received by the south, east and west facades. Figures 5 and 6 show the solar irradiance on the different surfaces of the building in the summer period (1st May to 30th September), when limiting the solar gains is required. As shown, the proposed 1000 mm deep brise soleil system considerably reduces the solar irradiance in the top 1 - 1.5m of the south facade. Figure 5 also presents the maximum solar gains, calculated for each floor and office area. The BCO-Guide to Specification 2014 suggests that solar gains in office buildings should fall in the range of 50-65 W/m2. As shown, solar gains do not exceed the maximum recommended value of 65 W/m2. The table below shows the maximum solar gains calculated for each office area, as well as the difference compared to the baseline scenario.


Baseline Option A Baseline Option A

Ground floor office 1 ~8.87 8.97 (+0.1 kW) 53.47 54.03 (+1.03%)

First floor office 1 ~9.94 10.45 (+0.51 kW) 59.88 62.95 (+4.87%)



Figure 5: Option A, Solar irradiation on the south facade, (1st May to 30th September)

Figure 6: Option A, Solar irradiation on the north facade, (1st May to 30th September)


54.03 W/m²


53.26 W/m²


62.95 W/m²


62.92 W/m²

1-1.5 m




2.3 Option B: Vertical brise soleil, length 1000m

Simulations were run to quantify the amount of solar radiation received by the south, east and west facades. Figures 7 and 8 show the solar irradiance on the different surfaces of the building in the summer period (1st May to 30th September), when limiting the solar gains is required. As shown, the proposed 1000 mm vertical brise soleil system considerably reduces the solar irradiance in the top ~1.20m of the

south facade. Figure 7 also presents the maximum solar gains, calculated for each floor and office area. As shown, solar gains do not exceed the maximum recommended value of 65 W/m2. The table below presents the maximum solar gains calculated for each office area, as well as the difference to the baseline scenario.


Baseline Option B Baseline Option B


First floor office 1 ~9.94 9.89 (-0.05 kW) 59.88 59.58 (-0.50%)



Figure 7: Option B, Solar irradiation on the south facade, (1st May to 30th September)

Figure 8: Option B, Solar irradiation on the north facade, (1st May to 30th September)


53.89 W/m²


49.77 W/m²


59.58 W/m²


59.53 W/m²

~1.20 m




3 Sunpath images The images below (i.e. Figures 9, 10 and 11) show the solar angle at 12 noon on 21st June, 21st September and 21st December (top to bottom). These images illustrate that the installation of brise-soleil in the south facade will not only reduce the undesired solar gains during summer period (due to high summer sun), but will also allow low-level winter sun to enter the building during winter period, which can contribute to the reduction of the space heating demand.

Figure 9: Sunpath on 21st June

Figure 10: Sunpath on 21st September




Figure 11: Sunpath on 21st December

4 Conclusions The general conclusions of this design note are listed below: - The baseline scenario is the best performing brise soleil system, as solar gains can be effectively

reduced without blocking natural daylight. - A combination of the baseline scenario (for the first floor offices) and Option A or Option B (for the

ground floor offices) can also be recommended. Option A leads to acceptable solar gains for the ground floor offices, i.e. 54.03 W/m2 and 53.26 W/m2. These are significantly lower than the recommended maximum value of 65 W/m2.

- Option B performs similar to the baseline scenario, but depending on offset from the glazing this might hinder outward opening windows.

- Horizontal brise soleil at roof level (i.e. Baseline scenario and Option A) can also minimise visibility from ground level of the photovoltaic panels or other external plant located on the roof.

incubator2, alconbury weald · design note – solar shading analysis...

Documents