HoCoDensity Housing Construction & Costs

The new volume published by a+t, which will be on sale on 29 June, forms part of the Density series, dedicated to the analysis of collective housing. HoCo is noted for including construction systems within the field of study and comparison, besides the costs of each project.

Comparative analysis of 32 collective housing projects Dwelling density Residential density Floor Area Ratio Developer type Users Uses Floor plans Housing types Facade systems Roof systems Sustainability strategies Costs per square meter of gross floor area

Characteristics:HoCoDensity Housing Construction & CostsDensity SeriesAurora Fernndez Per, Javier Mozas, Javier ArpaSoft cover (23,5 x 17cm): 464 PagesEnglish/SpanishISBN: 978-84-613-3080-5Price: 45euro

Proyects:ADAMO-FAIDEN ARQUITECTOSBuenos Aires. Argentina. 2008

AGUINAGA Y ASOCIADOS ARQUITECTOSMadrid. Espaa. 2008

ALLFORD HALL MONAGHAN MORRISLondon. United Kingdom. 2007

ANA ARCHITECTENAmsterdam. Netherlands. 2007

ARONS EN GELAUFF ARCHITECTENGroningen. Netherlands. 2007

ATELIER KEMPE THILLAmsterdam. Netherlands. 2007

AVA ARCHITECTSPorto. Portugal. 2008

BECKMANN - NTHP ARCHITECTESParis. France. 2007

BEVK PEROVIC ARHITEKTILjubljana. Slovenia. 2006

BEVK PEROVIC ARHITEKTIMaribor. Slovenia. 2007

BIG+JDSCopenhagen. Denmark. 2008

COLL-LECLERC ARQUITECTOSLleida. Espaa. 2008

DOSMASUNO ARQUITECTOSMadrid. Espaa. 2006

dRMM ARCHITECTSLondon. United Kingdom. 2006

EDOUARD FRANOISParis. France. 2008

EMMANUEL COMBAREL DOMINIQUE MARREC ARCHITECTESParis. France. 2006

FOREIGN OFFICE ARCHITECTSMadrid. Espaa. 2007

FREI ARCHITEKTENRohr. Switzerland. 2007

GIGON / GUYERZurich. Switzerland. 2007

HAMONIC + MASSONParis. France. 2008

HVDN ARCHITECTENAmsterdam. Netherlands. 2008

KASPER DANIELSEN ARCHITECTS / FUTURE SYSTEMSCopenhagen. Denmark. 2008

KOKO ARCHITEKTIDTallinn. Stonia. 2007

LEHMANN FIDANZA & ASSOCISFribourgh. Switzerland. 2009

LPEZ-RIVERA ARQUITECTOSBarcelona. Espaa. 2007

MVRDV, BLANCA LLEMadrid. Espaa. 2009

OFFICE dA, BURT HILLBoston. United States. 2007

OFIS ARHITEKTICerklje. Slovenia. 2007

ONION FLATSPhiladelphia. United States. 2009

POOLEN ARCHITEKTENCulemborg. Netherlands. 2008

ROLDN + BERENGUBarcelona. Espaa. 2009

URBANUS ARCHITECTURE & DESIGNGuangzhou. China. 2008

HoCo. Aurora Fernndez PerLets choose housing as the essential object of the cityLets have a look at the place wheres its implemented (urban extensions, downtowns, outskirts...)Lets check the occupancy data of the territory in which it is located (number of inhabitants, density...)Lets check the insertion into the urban grid (plot occupancy, planning permission, number of dwellings...)Lets find out whos doing the development (private initiative, public, mixed...)Who are the users? (the young, the elderly, anyone...)With a bit of luck there might be other uses in the project (businesses, offices, facilities...)Lets ask the authors nicely to let us know the build cost per m2.Lets adapt the cost to the purchasing power of the country where its located. This is inevitable if we want to compare on equal footingOnce inside, lets see how the common spaces are distributed.Lets find out how many dwelling sizes there are in each project (1, 2, 3 or more bedrooms....)Lets have a snoop around the building sections (1:50).Lets rake through the details (1:20).Lets look at how the materials appear in the facade and on the roof.Lets analyze the layers of the envelope with a simple colour code.Lets ask the authors which sustainable strategies theyve used (sometimes they reply, sometimes...)Lets add a good collection of photos.Lets do this 32 times and compare.Finally, lets add some thoughts and findingsThis is, more or less, what we call HoCo

HoCo CostsHoCo, the new volume published by a+t in the Density series is not a good practise manual, but is a review and comparison of real cases.The authors of each project provide the build cost per square metre and it is this data which orders the book, from low to high. In order to put them in order we have converted the local currency provided to us by the authors into international dollars, which is the hypothetical currency unit which expresses the Purchasing Power Parity (PPP) between countries, updated yearly by the International Monetary Fund. In each project we establish the relation between the local currency and the International dollar based on the nominal per capita Gross Domestic Product of each country, in US dollars and in International dollars (PPP), provided by the IMF. For instance, the calculations we have applied to a project built in Buenos Aires are the following: Nominal per capita GDP of Argentina: 8,146 USD (imf.org 2008)GDP in values of purchasing power parity (PPP) of Argentina: 14,376 $PPP (imf.org, 2008)From which we can infer that 1USD in Argentina is the equivalent of 1.76 $PPP, that is goods costing 1USD in the USA would cost 1.76USD in Argentina.

Hence, the project implemented in Argentina, with a construction cost of 3,071 ARS/m2 is equal to 878 USD, which translated to International dollars becomes 1,547$ PPP, which is the value set out in the Costs index.

HoCo RoofsThe analysis of building solutions is one of the main contents of HoCo, the new volume published by a+t in the Density series. Housing is a very fitting field for experimentation to try out proposals for the envelope, always playing with budget constraints and local regulation constraints. We wanted to compare all the projects by applying a simple colour coding, such that all the layers forming the envelope can be identified in each and every one of them. In the case of roofing we have also included garden terraces. The most remarkable aspect is the ever-increasing incorporation of vegetation into the fifth faade, not only as a sustainable strategy, but also as a space for common use.

HoCo facadesThe projects included in HoCo, the new book on housing edited by a+t within the Density series and it focuses on the construction solutions adopted. Some of the faade solutions standing out are:

Specific processes like aliphatic polyurethane coatings or concrete colouring in order to obtain glazes and non homogeneous colours. Superficial coatings with metallic colours, such golden paint or bright silver iridescent renderings.

Products derived from cement, such us coloured fibre cement boards and composite resin panels are a major faade cladding system. Besides, they are used for roof cladding, instead of ceramic and slate tiles. Their formalization ranges from undulated to flat boards, and they have become a medium-tech alternative to the traditional brick revetment.

Steel or aluminium plates range from stretched to corrugated, flat or bent. They are commonly used due their low price, easy installation and durability.

Prefabricated elements include some concrete slabs of the exterior entrance galleries and steel bathroom pods, which are built off site and mounted on site. Industrialised fabrication systems also include curved concrete panels, coloured with marble powder and reinforced with glass fibre. They are made-up out of a limited number of moulds

Structural insulated panels are often used as an alternative to brick or concrete block walls. They consist of a core of molded expanded polystyrene (EPS) insulation with engineered oriented strand board (OSB) laminated to the top and bottom faces.

The traditional mortar rendering of walls has evolved to one-coat plasters or mortars applied over external wall insulation systems

HoCo DensityLand occupancy and the construction of the compact city continue to be the basis of the Density series, which is now being extended with HoCo, the new volume on Housing, published by a+t. This time we have tried to better understand the context of each intervention through wide aerial views of the surroundings. The variety of sites, from small nuclei of population to consolidated urban centres, taking in city extensions and recovered urban voids, is enriched by the different lifestyles still observed in the 12 countries that have been included.We add the type of promotion, the type of use and the type of user as essential factors in order to understand a project, along with the cost. As far as densities are concerned, the range oscillates from that of 57 dwellings per hectare of a project located in a small Swiss town to those of over 500 dwellings per hectare reached

by projects located in cities as dense as Barcelona or Paris. The density data of each project refers to the net plot densities.

HoCo SustainabilityThe most remarkable sustainability strategies featured in HoCo are:Industrial construction system throughout the use of custom integral aluminium formworks: speeds-up execution time and eliminates debris in the construction process.Rainwater collection and re-use for irrigation.Green roof allowing for better thermal insulation and prevents the heat island effect. Use of timber products coming from socially and environmentally responsible forestry.Use of sound insulation systems besides thermal insulation, in order to protect from outdoor noise as well as to protect from noise originated in other dwellings.Use of entirely recycled materials, materials with recycled components, or subsequently recyclable materials.Heat recovery ventilator: the heat given off in the mechanical ventilation process goes back to the housing units.The car park is located above grade and not underground: it makes use of daylight and natural ventilation.Private parking with electric car charging port.Zip car located in the garage for resident useStorage space meant specifically for bikes.