Sustainability at 30 St Mary Axe
When you enter 30 St Mary Axe, you will be inside London’s first environmentally sustainable tall building. In keeping with its commitment to sustainable development, Swiss Re sought to minimise the building’s impact on the environment. Among the building’s most distinctive features are its windows, which open to allow natural ventilation to supplement the mechanical systems for a good part of the year.
The building takes maximum advantage of natural light. This is largely thanks to the lightwells that are one of the building’s hallmarks. The lightwells create the distinctive spiral design that wraps around the exterior. These triangular cutouts, six in each floor, allow penetration of daylight and fresh air to penetrate deep into offices. Floor-to-ceiling windows also contribute to the sense of openness.
Sustainable development and 30 St Mary Axe
A common definition of sustainable development is given by the World Commission on Environment & Development 1997: “…development that meets the needs of the present without compromising the ability of future generations to meet their own needs”. The key environmental aspects of the design are as follows:
Natural daylight and ventilation
- The six fingers of accommodation on each floor, configured with lightwells between, maximise daylight penetration, reducing the time that artificial lighting is required. Light level and movement sensors prevent unnecessary lighting, reducing energy consumption and cooling loads.
- Wind pressure differentials generated by the building’s aerodynamic form assist natural ventilation through the lightwells and reduce the requirement for conventional air conditioning. As a result energy consumption and carbon dioxide emissions are significantly reduced.
- The Building Research Establishment’s (BRE) annual energy consumption guideline for low-energy mixed-mode offices is 175 kWh/sq m. It is anticipated that Swiss Re’s new building will surpass this figure by up to 25 kWh/sq m in its optimal low energy configuration.
External envelope
- The ventilated double skin façade reduces heating and cooling requirements. Its performance can be tuned to maximise benefits that the prevailing internal and external environment might offer.
- Blinds located within the cavity of the ventilated double skin façade intercept solar gain before it enters the office environment, intercepted heat can then be reclaimed or rejected depending on the requirement for heating or cooling.
Building systems
- The building’s primary fuel is gas, one of the cleanest available.
- Low energy light fittings are specified wherever possible.
- De-centralised on-floor plant offers the flexibility to supply and control mechanical ventilation on a floor by floor basis. By closely matching supply with demand, energy consumption is reduced compared to a central system for the whole building.
Transportation
- Comprehensive public transport facilities surround the site to reduce dependency on private cars without placing undue load on any one element of infrastructure.
- The provision of cycle spaces within the basement is three times that of the minimum standard required, which together with shower and changing facilities, encourages this alternative means of transport.
- There are no private car parking spaces in the building.
The working environment
- Providing a working environment that enjoys external awareness, daylight, natural ventilation and offers individuals a degree of control over their personal condition has productivity benefits.
