Consultants in Architecture & the Sustainable Environment


Case Study: Heelis 
Diagnosis & mitigations for energy inefficiency & poor thermal performance

Heelis is the Head Quarters building for the National Trust in Swindon. Fielden Clegg Bradley Studios designed the building to emulate the Brownfield land's surrounding engineering works and the Great Western Railway. Max Fordham provided the comprehensive sustainable strategy.


As President of the National Trust, Prince Charles showed a great interest in the development of the design and famously threatened to resign if the designs were not sustainable enough!


The sustainable strategy included many elements with great attention to detail. The main elements were natural wind-driven stack ventilation, and a comprehensive system of solar shading to reduce overheating. Natural daylight was provided by the north-facing roof lights, and south-facing roof panels were fitted with a vast array of photovoltaic panels to generate solar energy.

In the post-occupancy reports, it was shown that there was a drastic shortfall in energy harvesting compared to the demand of the building. 


In 2017 the total energy consumption was 101,403KWh, yet the energy harvested was on 46,000KWh. 

We found that the culprit for this shortfall was the Communication Room which had been fitted with two mechanical air conditioners to keep the servers cool. The air conditioning units alone used a staggering 50% of the total energy consumed.


The remedial prescription aimed to increase renewable energy production but most importantly reduce energy consumption with the Communications Room as the clear target.


The two-fold proposal was to install rotating arms onto the photovoltaic panels so that they could follow the sun more efficiently and maximize the number of harvesting hours every day. We chose to use an earth tube fitted under the front flower bed to passively cool the Communications Room with a constant feed of cooled fresh air to eliminate the need for mechanical cooling. The calculations showed that in the extreme summer heat of 35°C, a cooling temperature of 18°C can be obtained. Alternatively, when taking a severe winter temperature of -10°C, an outcome of 3°C can be obtained.


In conclusion: This case study sought to understand the sustainable elements of Heelis and identify concerning issues that needed resolving. A thorough examination of the sustainable strategies and targets revealed that the predominant problems to address were the excessive use of energy and shortfall in solar energy harvesting. 

Additionally, it was shown that modification to the existing photovoltaic panels to tilt according to the seasons would optimize the number of hours that solar radiation falls on the panels, increasing the capacity for solar energy harvesting.    


Please contact us for the full technical report (free).