Sheppard Robson Hammersmith Road

Sheppard Robson’s design team set out to create a specific design aesthetic for the Bechtel House facade, optimise it for good energy and daylight performance whilst working towards high regulatory goals for the project as a whole.

South Facade Rendering Bechtel House

Quick Stats

Location: London, UK
Floor Area: 30,000m2  (322,917ft2)
Use Mix: New Build Office
Number of Floors: 9-12 Storeys
Project Goal: UK Building Regulation (Part L, Criterion 3) & Building Performance Rating (BREEAM Excellent)

Sketch Strategy Bechtel House

By calculating the impact of several shading device types and depths, the team was able to choose an optimum design that reduced energy use, bad south solar gains and cooling loads. Using Sefaira for SketchUp’s real time analysis, Sheppard Robson were able to understand the impact of shading types and depths, streamlining from about twenty different options to an optimised design that combined high performance, good daylight and a coherent design aesthetic.

Process & Approach

The team started by focusing on the south block, as it suffered from more solar exposure than the north block. They created simple models of the south block starting analysis on a fully glazed base case (image 1) then testing options with reduced glazing ratios (image 2). Comparing energy use, cooling loads and daylight levels, the team settled on an option with the optimum glazing ratio (image 3).

Glazing Tests 1-3

Image 1 Cooling Load: 403, 987kWh South Solar Gains 388, 050kWh Daylight Level (sDA) 87%
Image 2 Cooling Load: 386, 465kWh South Solar Gains 322, 581kWh Daylight Level (sDA) 86%
Image 3 Cooling Load: 386, 465kWh South Solar Gains: 322, 581 Daylight Level (sDA) 86%

Glazing Ratio Tests: Result Comparison

Next, the team focused on reducing south solar gains and the cooling load by testing selected shading options; 0.5m horizontal projections, 0.5m vertical projections, a combination of 0.5m horizontal + vertical projections and a 1.0m Horizontal projection.

Narrowing down to even more bespoke shading solutions, the team tested a tapered vertical fin, a tapered vertical fin with double horizontal shading and double height chamfered panels.

Shading Tests-1-3

Outcomes

The optimised tapered vertical fin, tapered vertical fin + 2 horizontal projections and double height chamfered fins were most effective for reducing cooling, energy use and bad south solar gains.

Graph plotting Shading Types and Cooling Load

Graph plotting Shading Types against Energy Use

Graph plotting Shading Type against South Solar Gains

Graph plotting  Shading Types against Heating Load

Impact on design

The team selected the optimised tapered vertical shading device for the north facade and the tapered + 2 horizontal projections for the south facade.

Taking it one step further, sun path diagrams were made to understand how different building services systems would affect daylight levels within the interior spaces. Comparisons were made between daylight penetration when a “chilled beam + exposed soffit” air delivery system is used and when a “suspended ceiling” system is used.

Sectional sketches showing the impact of design choices on building system

Results & Final Design

The team selected the chilled beam & exposed soffit option, opening up sightlines to the sky and allowing daylight deeper into the room. Upstands at window level offer additional insulation but are kept to a level that does not reduce daylight levels.

North Facade Rendering Bechtel House

North Facade

Bird's Eye View, Bechtel House

By testing several design options and optimising the final outcome for daylight and energy performance, Sheppard Robson were able make a clear case for their preferred design and confidently steer conversations with their M&E engineer.