Introduction

This is a modest two-storey office building (410m2 for 30 people) with exhibition and ancillary spaces. Almost 50% saving on energy use was reached by significantly higher insulation than Irish building regulations. Next to that the high thermal mass, good controlled infiltration and day lighting contributed to the 50% reduction on space heating and electricity use.
The constructions costs for this modest building were just 550,000 Euro for a total of 410 m2 office floor.

Objectives and target audience

The green Building Objectives:-

• To exemplify and promote efficient energy usage;
• To provide high quality working conditions for the users;
• To make a positive contribution to the existing campus;
• To place minimal demand on non-renewable energy sources;
• To make an innovative response to traditional materials and energy standards;
• To demonstrate that it was possible to achieve these objectives with construction costs not exceeding those of a conventional building.

Financial Resources and Partners involved

The budget for the entire project, including design fees, was € 635,000. Cost control was a primary concern of the client, and the building was delivered on time and within budgets. Up to now the building has performed to satisfactory.

Process

The client (Irish Energy Centre), was a new semi-state agency, the Irish Energy Centre (IEC) was formally established, with the help of the EC Structural Funds Programme, in January 1994. Its role is to promote the efficient use of energy in all sectors, offering advice, information and expertise.
The client wished to construct a building which would itself demonstrate energy awareness in its design and operation.
To this end it commissioned the Energy Research Group (ERG), University College Dublin, to draw up a general and energy performance brief and advise on selection of the site for the project. This work was partly funded under the European Commission’s THERMIE Programme.

The building envelope was designed with U values significantly better than required by the Building Regulations.
With Ireland’s high wind speeds control of infiltration is critical. Before work started on site the contractor was ‘sensitised’ to the importance of workmanship for the energy performance of the buildings.
Energy efficiency was the primary objective of the design, but materials, components and construction methods were selected with their effects on internal, local and global environment in mind. Locally produced recyclable materials with low VOCs were given preference whenever possible. Only new products of which performance was already proven were selected.
The extensive use of concrete in the building’s construction (ground and first floor structure, some internal and all external walls) provides substantial thermal mass. There are no raised floors or suspended ceilings. Internal wall surfaces and ceilings are plastered and painted, and floor finishes in the atrium and corridor areas are black natural slate to enhance thermal performance.

High levels of insulation and thermal mass with good control of infiltration all help to reduce the heating load. There are also some south-facing windows to the offices and to all cellular spaces.

Limited south-facing glazing, natural ventilation and the thermal mass of the building all reduce the likelihood of overheating. In the office spaces cross-ventilation is manually controlled by openings at each workspace, while the stack effect in the atrium assists the natural ventilation of the areas opening onto it. In the atrium two punkah fans at high level prevent stratification. Reflective metallic venetian blinds mitigate solar gain by 15 to 20% compared with normal internal blinds. Deciduous trees have been planted in the east and west-facing courtyards to screen the sun in summer and filter light in winter.

Windows are evenly spaced and are higher than average (3 m) so that light is cast deep into the room. Glazing on opposite sides of the room provides excellent light distribution. The masonry window reveals are splayed to increase natural light and reduce glare. The atrium brings borrowed light into office spaces to either side.
Energy efficient lamps were specified throughout. Control features include daylight sensors, dimmable light fittings, infrared occupancy sensors and programmable time scheduling. When daylight levels fall below 300 lux the artificial lighting comes on in occupied spaces.

Results

During the design stage the winter and spring hourly, daily and monthly heating loads of the building were calculated using the TRYNSYSBIO simulation tool. The results demonstrated that the basic design strategies were effective and were taken into account during the detail design stage.
Day lighting performance in the first floor offices was monitored within the context of the JOULE contract ‘Daylight Europe’.
Under overcast conditions Daylight Factors on the working plane were found to be in the range 5% to 10% and with good distribution.

Critical Success Factors / Challenges

Most solid waste generated in the Dublin area goes to landfill sites; in 1993 less than 10% was recycled. It is government policy to reduce municipal waste substantially through increased recycling.
On the Enterprise Ireland campus water supply and drainage are common to all buildings and a large network of underground services ducts runs below the main pathways. Water is metered as it enters the campus.
From the start IEC occupants had in place a paper recycling system. Since 1997 the building has also benefited from a campus recycling / safe disposal system for fluorescent tubes, batteries and similar materials.