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Kieran Timberlake's US Embassy: 'Nothing is ornamental, everything is performative'

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‘Project of a lifetime; this is as good as it gets,’ says Stephen Kieran


Last month I attended a ‘green embassy’ reception hosted by the US Embassy with talks by Lydia Muniz, director of the State Department’s Bureau of Overseas Building (OBO) and architect Stephen Kieran of Philadelphia-based KieranTimberlake Architects. Targeting both BREEAM Outstanding and LEED Platinum, London’s new American embassy is one of 40 live projects (worth a total of approximately $7 billion) in the OBO’s pipeline, and - according to Muniz, represents the ‘leading edge of our sustainability efforts’. Muniz spoke first, describing the choice of the Nine Elms site as ‘compelling, and a sign of a America’s commitment to the environment, to urbanism and to sustainability’.

Location plan

Location plan

Muniz explained to me later that the choice of a brownfield site marks a significant move on the part of the State Department away from suburban sites with cookie cutter embassies churned out in response to security concerns which have prevailed in recent years.

Site plan

Site plan

The new embassy also marks a renewed commitment to design quality at the State Department, where Muniz has put in place a Design Excellence programme. The OBO recently announced that Todd Williams Billie Tsien Architects will design a new American embassy in Mexico City. Highly articulate on the symbolic role of embassy buildings, Munz says ‘we should build buildings which project what we want to project about America.’ I couldn’t help remembering Jonathan Glancey’s quip in The Guardian when Kieran Timberlake’s competition win was announced: ‘nominally open to all and yet, in practice, tightly controlled’.

Kieran describes the Embassy project as ‘the project of a lifetime; this is as good as it gets.’ No aspect of the design is ‘ornamental, everything is performative,’ according to Kieran. The building is intended as ‘a diplomat for the environment’ which will provide a quality working environment. Though the initial brief called for LEED Gold, BREEAM Excellent and EPC B ratings, the architects suggested at competition stage that the building should aspire for the top ratings in all three categories, a strategy which is currently on target.

Internal landscaped gardens, representing different American regions, will carve a path through the building for employees.

Internal landscaped gardens representdifferent American regions.

Internal landscaped gardens will represent different American regions.

Internal landscaped gardens represent different American regions.

Below is an extended version of my recent interview with Stephen Kieran published in AJ 25.7.2012.

Stephen Kieran

Stephen Kieran

What was most important to you in the design of the new US Embassy?

There have been two thrusts from the outset. One is sustainability and that was generative. We always thought of the building as a diplomat for the environment. The second was the quality of the workspaces in terms of creating a high quality efficient environment for the Embassy to conduct its business in and for the staff to work in.

Isn’t the cube a very deep building?

No, the cube is dimensioned so that the distance from the perimeter to the core is about 15 metres. It is dimensioned for ideal daylight penetration which is supplemented with an interior light shelf. Daylight diffusion is effected through the outer scrim – the outer envelope around the perimeter.


What have you modified since the competition?

The design in all its general terms, as presented in the competition, remains. It is different in many many details. With Arup, we established a programme to ‘stair-stepped’ the building up to a really high level of environmental performance and that has been fleshed out since the competition.

Arup, Diagram of stepped environmental performance

Arup, Diagram of stepped environmental performance

In more specific terms, by the time we had understood all of the detail requirements of an embassy, we found ourselves in an energy deficit in relation to baseline US codes (ASHRAE) of about 9 per cent. That has to do with the nature of any embassy; there are so many  security issues.  You can’t for example use natural ventilation or mixed mode ventilation in any way for obvious reasons.   

Basically there was no single strategy that would get the building up to the level of performance to whch the Embassy aspired. It’s achieved by dozens of individual strategies, each of which incrementally may seem relatively minor. Some of them may only have an  effect of only 2 or 3%  but they all add up to really substantial change.

What percentage of the loads will be supplied by renewables?

The Wandsworth and London requirements are 20 per cent and we are aspiring to that but it’s not that easy.

The combined heat and power plant is the big one. It allows us to potentially share excess heat back out to a district grid which may be developed in Wandsworth. That’s a central part of the path towards carbon neutrality in the building.

Has the design process differed significantly from what you anticipated?

No it has not. We had a process and methodology pretty clearly mapped out and it hasn’t really differed in any substantive way.  Certainly the London planning submittals have been huge. We met regularly with constituencies here and made regular presentations.

How has working in the UK differed from the US?

The whole planning context in America is completely different.  In the US, zoning is more prescriptive.  Here it is all negotiated.  You also have a vast array of planning requirements which deal with matters such as right to light that are not typically written into US law. 

Has there been a knock on effect on other work in your office?

Sure. We have full-time research staff and the majority of work they undertake is environmental research and product development. There has been a knock-on effect on many fronts. We are able with this project to undertake some integration of photovoltaics with the external envelope. That’s actually quite an advance on a lot of levels which we’ve been able to develop with fabricators.

What do you consider the most innovative aspect of the building?

I would say the really innovative aspect of this is the totality of it and the complete integration of all these systems together. Nothing is added without being integrated with everything else – things as simple as storm water management, for instance. We are collecting water off the building and from the site and storing it in the pond. This is also a central part of the mechanical system of the building; it is the heat sink for the cooling from the building. And on and on that goes, that story of integration. Systems that are most often disaggregated and not used holistically are used in a way that is very synergistic in this building. And that is why we are able to step up its environmental performance as much as we have.

But isn’t that how you normally work? Or is it just the scale of this project?

It’s scale. It’s certainly how we aspire to work but we don’t always have the scale of project that can realize it.

Would you say that the approach to integrated design is further along on in the UK that it is in the US?

Practice in the UK is probably somewhat ahead of the US in environmentally terms. The leading practices in the US are every bit as sophisticated but my observation is that it is just deeper here, in part because of the regulatory environment. The requirements are not always as stringent in the US as they are in the UK. A lot of it is more voluntary in the US.


Are there any precedents for the thin film PVs you are using in the facade? 

There are applications of thin film PVs to many substrates, integrated in glass systems particularly in Germany, but a lot of what we are doing is forging new ground.  What’s of significance is the adherence of PVs in ETFE membranes.  A stressed skin membrane is formed around a structural armature that is held off the building. It gathers energy from the sun through the PVs but it also shields unwanted energy and diffuses daylight enterint the building.  The totality of the system performs multiple tasks.  The principle reason for the exterior envelope is daylight and glare management and protection of the building from unwanted solar gain.

What will it be like looking out through the screen? 

There are lots of spaces where you can look out between the panels. These are not cushions; it’s a stressed skin structure.  Above eye level there are PVs positioned on them.  In the competition, it was a cushion system but it has been developed as a stressed skin system. There is an armature of stainless steel that the ETFE stretches around.


How was the consultation process?

Wandsworth Council has been extremely supportive of the project and see it as a generator of urbanism in the whole area. 

View of Nine Elms 'built out'

View of Nine Elms ‘built out’

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