Case Study _ UN CITY, Copenhagen

The building for UN CITY in Copenhagen was completed in 2013 and it boasts some impressive green building aspects.

 

Shaped as an 8 pointed star, the building houses 1700 staff in 9 departments. Architects 3XN ensured that energy efficiency was maximized by employing these clever solutions:

• The central feature staircase connect the different wings of the building and encourages interaction among the staff… positive engagement and discussion is obviously a key component of the UN.

• Reclaimed land – an artificial island on the harbor ensures that existing valuable greenfield land was not used.

Context: The 8 pointed star on reclaimed land

HEATING & COOLING

• External aluminium solar shutter are controlled by workers from their computers. Perforations in the shutters ensure that daylight still permeates even as direct solar gain is excluded.
• Sea water is pumped into the buildings network of pipes to COOL the building, which almost eliminates the need for any mechanical cooling.
• A white recyclable membrane coats the roof which reflects solar gain to further assist cooling of the internal work environments

BUILDING FABRIC

• High U-values of building materials ensure that external envelope is well insulated.

ENERGY USAGE:

• Solar PV panels generate 297,000 kWh/yr. Approximately 1400 panels are located on the roof.

WATER CONSERVATION:

• aerator taps reduce water usage
• Rainwater is collected and used to flush toilets. Approximately 3000000 litres are collected annualy which is almost all the required water for the flushing of toilets.

LIGHTING

• low energy light fittings
• daylight is maximized via open plan layouts, which also allow flexibility in function – future-proofing.

 

AIR QUALITY

• outside air is filtered for indoor use, regulating humidity and ensuring a constant fresh supply.
• Chemicals and other pollutants are minimized through selection of construction and furniture materials.

Overall energy consumption is incredibly low at 50kWh/m2. When compared with the average commercial building consumption in the UK, this is exceptionally good:

Energy use indices (EUIs) for good practice and typical examples of the four office types (Source)

UN City would classify in the catogory number 4 – Prestige, air-conditioned which suggests typical consumtion of 560kWh/m2/yr, or good practice of 350kWh/m2/yr.

The building is LEED Platinum certified and was awarded the European Commision’s Green Building Award in 2012.

CREDITS
Location: Copenhagen, Denmark
Client: FN Byen (Copenhagen Port & City Development)
Gross Floor Area: 52.000 m²
Cost of Construction: 134.000.000 Euros
Architects: 3XN
Interior Design: PLH / UN Common Services
Contractor: E. Pihl & Son
Consultants
Engineering: Orbicon
Landscape: Schønherr

Strawbale Construction

As a waste product from Agriculture, haybales make a great sustainable building material. Haybales have excellent insulating properties and make for a very pleasing, organic finished result. Thatched roofs are common around the world so it was initially  suprising to me that using haybales for walls is not more common. This is largely possible due to the fact that the mechanization that resulted and straw-baling formation only came about in the 1850’s!

Original haybale construction in Nebraska

The first documented haybale building was a school in Nebraska dating back to 1902. When the cows started to nibble at it, the builders decided the plaster the walls. Following this, numerous haybale buildings sprouted up in the area.

 

Haybale walls tick the sustainability box for a number of reasons:

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– Renewable: Crops are grown every year and fast growing

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– Waste product: Apart from animal food, hay is a waste product from crop farming. A field of 1 hectare can produce between 4 and 6 tonnes of straw annually. An average size house requires around 10 hectares. Given that the UK has around 2 million hetares of crops, that is a lot of house material!

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– Low-embodied energy: Haybale construction should generally be used in areas where the hay can be sourced locally. This results is very short delivery / transportation which keeps carbon emissions down.

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– High insulation: the great insulation properties will reduce energy bills and improve thermal comfort as indoor temperatures are regulated.

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– Non-toxic and vapour permeable: bale walls have no off-gassing and allow a healthy passage of air which prevents mould growth.

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Haybales are treated much like over-sized bricks. Organised in a running bond, the bales are tied together using re-bar of bamboo or timber, or covered with a mesh. This can then be plastered with a lime, cement or clay based render.

 

Plastering of walls protects the straw and neatens the finished wall

Using mesh as a support for the plastering

A solid foundation is generally used, onto which the bales are placed. A moisture resistant membrane should be placed between the bales and the foundation.

Example detail of wall at foundation and window

Deatil of ‘Hoks Strawbale house’ which achieve a LEED Gold certification

The bales can be used as the structure of the building, or as the insulative infill to a steel / timber frame structure. A field bale will generally support 900kg per linear meter but it is possible to get highly compressed bales for greater structural loads, that can support up to 6000kg per linear meter.

Bale infill to timber structure

‘Balehaus’ is a project of the University of Bath, where prefabricated panels with hay infill where fitted together and rendered with a breathable lime-based plaster. More about the ModCell concept here.

BALEHAUS by Modcell

Haybale walls have very low thermal conductivity making them a great source of insulation. Thermal consuctivity of wheat is about 0.06 W/mk. For a bale wall 475mm thick this would achieve \ U-value of 0.123W/m2K. This exceeds the passivhaus requirement of 0.15w/m2K for walls.

Temperature test on a warmer day

Temperature testing on a cold day

Source

Because the haybale walls are plastered, this prevents the unwanted concerns of rats and mice / fire damage / water ingress. It is important that a good covering of plaster is used – around 25mm thick. If looked after, haybale walls can last for centuries.

Strawbale construction is perfect for cold enviroments

The NBS has now incorporated a guideline specification for Strawbale construction: http://www.thenbs.com/topics/Environment/articles/StrawBaleConstruction.asp

 

 

Hello World!

SUSTAINABLE!! Its a buzz word for sure! What does it actually mean and why the fuss?!

At its core, sustainability is about our consumption of resources.  The environments ability to replenish the source of material / energy such that the use of it is not depleted faster that it can be reproduced. Sustainability is informed by three key areas as shown in the diagram below…

Sustainable development diagram

My experience in architecture alerted me to the wastefulness that accompanies many design decisions and I realized a desire to investigate alternatives. Where to start though! There is SO much information on the internet and given the rise of the GREEN TREND it has become tricky to decipher genuine, high impact options from ‘green bling’ or suppliers claiming that their goods are environmentally friendly to increase sales.

There are a variety of codes and guidelines to assist professionals in creating architecture that is much improved on previous decades of high carbon, energy-sapping structures. LEED, BREEAM, Passivhaus, Code for Sustainable Homes, to name a few of the more useful. Different countries and climates require different strategies so that adds to the complexity. There is no simple, blanket solution… each building has its own challenges and priorities relating to the CONTEXT!! Key word that!!

There are many stages of a buildings life-cycle that require informed, sustainable decisions. The diagram below including my sketchy notes is useful for highlighting what these are:

Building process diagram showing additional stages of ‘Occupancy Evaluation’ and ‘Soft Landings’ to assist occupants to maximize energy efficiency and thermal comfort.

Studying the MSc Sustainable Building: Performance and Design at Oxford Brookes opened my eyes to the many solutions and problems in the quest for more efficient and comfortable buildings but also left me with many questions. Informed questions… so I now know WHAT I should ask and have a better idea of when I should be skeptical of so-called solutions. This has led to my creating this blog – continued research and general curiosity – and I hope that my journey will help you and others to grown in knowledge of the subject!

I plan to split my post content between 4 subject headers. This is based on a summarized version of the courses I studied on the MSc SB:PD:

SUSTAINABLE DESIGN IN CONTEXT

– a critical look at example buildings that embody sustainable principles

BUILDING FABRIC

– investigations into various building materials, their thermal conductivity and impact on the environment

LOW CARBON TECHNOLOGIES

– components of the buildings that improve energy efficiency and reduce waste. From Solar PV to composting toilets

POST OCCUPANCY EVALUATION

– Vital to the ongoing research into what works and what doesn’t… assessment of completed buildings at least 1 year into occupation. The cold facts (energy consumption – predicted VS actual) and the warm (or not!) feelings (occupants opinions).