Angel Building

London. 2010

  • Project Details
  • Completion: 2010
  • Cost: £72 Million
  • Clients: Derwent London plc

Angel Building is about redefinition; of an out-of-date building; of a forgotten service yard; of a fragmented street edge; and of the combination of workplace with public space. An existing concrete frame – extended vertically and horizontally to create a better contextual fit – is reused and wrapped in a highly-efficient glazed skin. A forgotten service courtyard is transformed into a six-storey top-lit public room of grand proportions, set at the heart of the building to offer a variety of spaces to convene, dine and repose. Once an unloved 1980s office building facing demolition, it is now a 355,300 square foot hub of activity that’s redefining workplace with its mix of public atrium, café, bespoke works of art and rooftop terraces. Through re-using the existing frame, the project has its cake and eats it, saving 7,400 tons of CO2 of embodied energy (the equivalent to running the entire new building for 13 years) while providing 40 per cent more functional area than previously.


BCO Test of Time Award 2015 AIA Award 2012 Chicago Athenaeum Green Good Design Award 2012 CIBSE Building Performance Awards: Refurbishment Project Award 2012 Islington Society Award: Best New or Restored Building in the Borough 2012 3R Awards: Office Category 2011 British Construction Industry Award: Judges Special Award 2011 British Council of Offices National Award: Refurbished & Recycled Workspace 2011 Civic Trust Awards: Commendation 2011 Concrete Society Award: Rejuvenation Award & Certificate of Excellence 2011 New London Award for Working 2011 Regeneration & Renewal Award: Design Excellence 2011 RIBA Award for Architecture 2011 RIBA Stirling Prize: Shortlist 2011

Energy Efficient System Design

Energy performance was key to delivering a high end building which would be welcomed by the local community. To achieve this much thought was put into reducing energy consumption through passive building design, energy efficient system design and renewable energy technology. These measures have achieved an approximate carbon saving of 20%, and a BREEAM Excellent rated building.

The Angel Building is serious about reducing energy usage, hence carbon emissions, hence running costs. It does this in three ways: firstly by minimising embodied energy in its structure, secondly by being equipped with a full range of energy-saving measures, and thirdly by being well-placed for public transport, and cycle-friendly.



Heat loss diagram



Passive Building Design

Careful consideration was given to minimise the effect of solar over heating to the office areas by providing a façade with a very high level of solar control.  This was achieved by combining high performance glazing with fritting to reduce solar energy being transferred into the space. In addition to ensuring the necessary compliance with the Building Regulations thermal performance criteria, this has also enabled a cooling system to be installed that offers high occupancy comfort benefits combined with low energy demands.

The overall insulation value of the façade is significantly better than the current Building Regulations demand.

Clever Concrete

Part of the energy strategy is the way the Angel Building re-uses the existing concrete frame of the earlier building on the site. This avoids the waste of energy and materials you get in a total demolish-rebuild scheme. New concrete, as seen in the atrium, uses ‘pulverised fuel ash’ – a useful by-product of power stations – which reduces its embodied energy and improves appearance. It is sourced from a concrete plant less than a mile from the site.

The solar coating in the glass gives it its blue hue

Displacement Ventilation

The office areas are ventilated and cooled using a displacement ventilation system. The system includes roof mounted air handling units feeding each core.  This displacement system provides the opportunity to use outside air for cooling, when suitable external ambient conditions permit.  This is commonly referred to as ‘free cooling’, as the chiller plant is not required to operate during these periods.  Free cooling will be available for approximately 80% of the buildings standard operating hours.  This has created a very energy efficient and sustainable building retaining upto 65% heat recovery.


Displacement ventilation system diagram

Water Cooled Chillers

The building cooling needs are served by two water cooled chillers with high seasonal efficiencies. Heat rejection from the chillers is achieved by cooling towers located at roof level of the building. This method of generating chilled water is recognised as a high energy efficient design, particularly when applied in large commercial office buildings.

Variable Speed Pumps

Variable speed controls for the heating and cooling water circuits circulating only the volume of water required to match the required load and for correct plant operation. 

A study undertaken by BRECSU for the Department of the Environment suggest that energy saving of 66 to 86% of pumping can be achieved in such installations.

Light Fittings and Controls

Lighting controls are provided to ensure the efficient operation of the lighting scheme and avoid its unnecessary use.  The lighting design will incorporate high efficiency fittings that will aim to exceed the requirements laid out in Part L2A of the Building Regulations and circuits set out in order to allow daylight at the perimeter.

All luminaires will be provided with high frequency electronic control gear.  In addition, fittings installed adjacent to the building perimeter will be controlled by daylight sensors which will switch and adjust the lighting levels in relation to external environment to reduce energy use.

Rainwater Harvesting

A rainwater harvesting scheme serving toilet flushing has been installed to increase the sustainability of the Angel building. This system not only reduces energy at water authority’s central pumping station, but also reduces the buildings reliance on the local supply.

Renewable Energy

The buildings renewable energy contribution was achieved using a biomass installation to produce hot water used for heating and the hot water demand. Two bio-mass boilers located within a ground floor plant room are fed from an adjacent fuel store.  The bio-mass installation gives the building a 15% renewable energy contribution.

Renewable Fuels

Two biomass boilers provide 100% of the heating demand,  reducing dependence on any single fuel source. The wood pellets used as fuel can be sourced locally and the ash is biodegradable and soil-enriching.

Water Savings

The wide roof and terrace areas of the Angel Building are ideal for catching rain, and that’s just what they do. The harvested rainwater is filtered and used for toilets, window cleaning and bin washing. Toilets and taps are water-efficient, and urinals are waterless. All in all, the building saves the equivalent of 455,000 WC flushes per year.

Sustainably - Sourced Timber

It is Derwent London’s policy on all its buildings to use only timber from renewable sources.

Intelligent Lighting

This is one of the most important contributors to lowered energy demand. The Angel Building deploys a high quality, technically advanced lighting system. Incorporating a ‘DALI system’ (Digitally Addressable Lighting Interface), it is readily adaptable to different levels of daylighting, occupancy and changes in space planning. It’s clever and it saves energy.


Existing mature trees have been retained and new semi-mature trees and a meadow habitat have been added to the landscape around the building, which is designed to create an agreeable micro-climate between streets and building. Bat flight corridors are protected.

Public Transport and Cycle Scheme

When occupied several thousand people will work at the building and a significant amount of carbon generated during the life scheme will be through energy used during their journeys to and from work.  In response, a number of measures have been taken to keep this to a minimum:

> Minimum of 5 car parking spaces, including wheelchair accessible spaces) and charging points for electric vehicles

> A secure bike store plus an additional 30 bike spaces

> Each WC core contains a wet room

By virtue of its location, the Angel Building also has excellent access to public transport with a bus stop directly outside the main entrance and Angel tube stop two minutes walk away.

External bike racks


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