Barcelona Eixample is a new area of the city laid out in huge grid, each cell consisting of 120m x120m block with filleted sides and an inner courtyard.

The cells originally were not meant to be enclosed on all sides, but the economic demand for space soon meant that nearly all the cells were enclosed, producing a form designed without climate in mind.

The aim of the project was to take one of the established grid forms and provide a integrated design solution for an office where the specific climate of Barcelona is its main design factor.

Barcelona Eixample

The Specific Climate Study

No facades face directly south making winter solar collection difficult (The Eixample is based on a grid at 45 degrees off north).

Roof ideal for solar collection although currently horizontal meaning loss of energy by reflection.

The building type - office - is generally used between the hours of 8 to 1800 hours making night heating and cooling possible.

The site receives a reliable, south westerly wind and good average hours of sun in both summer and winter.

Office also where we spend most of our lives, the design solution should also take into account the changing work place and the need for a good working and social environment.

Surrounding (unchangeable) buildings shade lower areas of building form making low level solar collection difficult.

The nearly 30m deep plan makes natural lighting and ventilation awkward.

Busy roads surrounding the cell create fumes, noise and dust making natural cross ventilation near impossible.

Psychometric chart with the Comfort zone highlighted

The specific context of the design solution requires the need for both heating and cooling at different times throughout the year.

In cold weather: maximise solar and other ‘free’ heat gains, provide good heat distribution and storage, reduce heat losses and allow for suitable ventilation.

In warm weather: minimise heat gains, avoid overheating and optimise cool air ventilation and other forms of natural cooling.

The form of the building was revised:

to allow better penetration of low level winter sun directly into office spaces

to reflect the noise from the traffic

to allow a more even distribution of solar gain through the whole of the building

to allow the use of sun spaces to collect low level solar gain directly from the south without being shadowed by the building form

and to achieve better daylighting especially on northern facades

The car park was positioned on the lower floor to allow easy access and to prevent low level office spaces fronting straight on to the busy road whilst achieving better daylighting.

The sun spaces are located in positions in which to receive optimum heat gain for the building form.

Eight main office blocks are created, divided by glazed voids which form sun spaces. As well as collecting solar energy in winter they also have other uses:

as light wells allowing light to penetrate deep within the building plan

as circulation spaces between offices

as semi-outdoor meeting places

as places to aid orientation to break up the otherwise monotonous façade and to break up the building into easily managed thermal zones.

The heat energy is then stored in the concrete floors and walls which have a high thermal mass. The concrete is made with recycled aggregate and made dark to increase its absorbency.

Sunspace section winter

In summer when there are leaves on the trees in the garden atriums, they serve a similar purpose, chilling the incoming air before it enters the office space. In summer the garden atrium spaces act as sources of fresh, externally conditioned air and daylight.

Sunspace section summer

Where possible the heat energy is distributed throughout the building by natural means by conduction through the floor slabs and walls, by convection through air and by radiation off inside surfaces.

However mechanical fans and pumps are used where and when needed. An integrated building management system (BMS) is used to control many of the building’s functions including the distribution of heat energy between the sun space and the offices.

Office long section winter

In winter the collected heat energy rises to the top of the sun space where a low energy fan sucks the fresh warmed air through the high thermal mass of the office floor/ceiling slabs. The air is emitted through ducts in the floor where it provides the office users with fresh warmed air. A separate low energy fan sucks the warm stale air through holes in the ceiling, where it continues to pass through the floor/ceiling slab until it reaches the next sun space, where the air is passed thorough a heat recovery wheel before being evacuated. The recovered heat goes directly into the heating of the new incoming fresh air, where the whole process will start again. This system distributes heat evenly around the whole building. Compensating areas that to not receive solar gain, helping to moderate the temperature between the thermal zones.

Office short section winter

In summer cooling towers are used to catch the prevailing wind and draw the hot fresh air down the towers, where high pressure water misting nozzles are used to induce downdraught cooling by evaporation. A method based on a prototype by Mario Lucinella Architects. The system exploits a version of evaporative cooling as traditionally used in the Middle East where the windcatchers guide external air over porous pots filled with water, inducing evaporation and lowering air temperature before it enters the interior. Compared with air conditioning, the system benefits from lower capital maintenance and energy costs and eliminates the need for a refrigerant. The advantage of passive down draft evaporative cooling (PDEC) for urban locations is that air is taken in at high level, the external skin can be sealed against noise and pollution.

At night the roof vents in the cooling towers and in the garden atrium can be opened by the BMS to induce night time cooling.

The cool air will drop down and chill the floor slabs for the following day. Overnight cooling of the structure is crucial - overcool and you increase the morning warm up load, undercool and staff will suffer as daytime temperatures climb.

The main internal gains in such office space consist of lighting loads, visual display units, photocopiers and people. Such internal gains can be excessive in deep plan buildings. The use of natural daylighting should considerably reduce the lighting load. The use of modern, more energy efficient appliances and lighting equipment will also reduce these gains. Photocopiers, printers and coffee machines are housed in the service cores rather than in the open plan office spaces. Grouping these together in a central area allows heat gains to be dealt with by local fan coil units, rather than increasing the temperature of the offices.

Solar gain, welcome in winter time, can result in uncomfortable warm interiors a few months later. Solar gain is controlled in many ways throughout the building.

In the garden areas screens of vegetation admit sun in winter when the leaves have fallen. In summer the foliage provides shade whilst allowing filtered daylight to reach the interior

In the main office spaces external louvres are used on south-easterly, south and south-westerly facades. The louvres prevent high level summer sun from passing into the building, yet still allow low level winter sun and high level sky light to penetrate and be reflected on to the ceiling, both increasing solar gain in winter and decreasing it in summer, at the same time achieving good natural lighting all year round, internal blinds allow for individual control.

Natural materials are used where possible - wooden handrails, stone, wood. Again used to heighten the user’s awareness of the building environment and to aid orientation. Different materials used in different areas. Beech handrails in one sun space, pine handrails in another. The office floors are essentially the same and therefore can be made as prefabricated slabs, cutting costs, time and casting materials.