An award-winning office development in Co. Tipperary brings together an innovative natural ventilation system with excellent air tightness results and a high performance building envelope to create a comfortable and cost-effective office environment.
The co-located site in Tipperary town is home to decentralised offices for the Department of Justice and Equality and the new civic offices for Tipperary Town Council. Arranged in two separate buildings east and west of a central civic plaza, the project is underpinned by a sustainable ethos that can be identified at almost every point in the design process.
The construction contract was won by Stewart, a company which has a long-established track record in sustainable building. The Galway firm built the Bucholz/McEvoy designed SAP offices in Ballybrit, Galway, along with the BREEAM Excellent rated decentralised offices in Roscommon in 2010.
Stewart retained Coady Partnership Architects for the project. The two companies worked together on a number of other buildings, including the aforementioned Roscommon offices.
Thomas Sexton, project architect for Coady explains that the design team employed a collaborative approach. Contractor, architect, structural, civil and M&E engineers, landscape architects and others all came together in a round table format to tease out the various issues.
“We worked all our strategies out early on,” says Sexton. “Buildabilty solutions, structural solutions, we talked with M&E about ventilation strategies, we discussed building width, grid depth, steel vs concrete, precast vs insitu, grid structure, the depth of the plan for light penetration and so on.”
Paul Stewart of building contractors Stewart says that his company makes extensive use of technology to facilitate communication and drive quality on all of their projects. Construction management software is used to plan, co-ordinate and control the process from planning through to completion. It has, he says, had a hugely beneficial impact on the information flow that onsite quality depends upon.
“Basically,” says Stewart, “we wanted to eliminate the generation of twenty different Excel spreadsheets and create a single live environment in which to communicate, monitor and follow up.”
Everything related to the project – from submittals and punch lists to drawings and RFIs (requests for information) – now sits inside one system. There are no misfiled emails or replicated spreadsheets. A clear audit trail is generated automatically, showing who changed what, where and when.
Stewart explains that the company also created a non-conformance tool within the system, which acts as a kind of live snag-lister, allowing the client far more powerful interaction with the project than ever before.
The app sits on the client’s phone, and during regular site visits, he notes a particular issue, snaps a picture from within the app and these are automatically sent to the right person within the project team. This process is a marked break from tradition, where typically, snaglists are not drawn up until close to completion.
“This allows us to incorporate the client in the process,” says Stewart. “By giving their input earlier, we can solve the problem earlier. It promotes a collaborative approach and suggests to them that we’re all in this together.”
A variety of separate tools within the system facilitate everything from ongoing quality control to health and safety. In the latter module, a series of leading questions prompts the person responsible to ensure that everything is exactly as it should be.
Paul Stewart again: “The checklists ask, ‘Have you got your AF1 form up? Where’s your first aid located? Are there signs up for X, Y and Z?” Similar checklists are used to monitor scaffolding, excavations and so on.
With these systems helping to maintain quality control onsite, the project team gets the creative space to explore ways of boosting the environmental profile of the project.
The Stewart/Coady partnership had used an insitu concrete slab with columns on the Roscommon offices. In Tipperary, they had intended using the same approach, but then realised that by using precast concrete flooring sourced locally, onsite wastage would be substantially curtailed. “So even at that stage we were looking at supply chain,” says architect Thomas Sexton. “We wanted to show the OPW that we could improve on the green credentials of the project, even at that specification level.”
The design team sought to preserve as much of the site’s natural features as possible. Works exclusion zones were instigated around trees, while archaeology discovered during excavations was preserved and documented. The civil engineers used a natural dip in the terrain to facilitate a drainage solution and avoid the need for attenuation tanks. Swales were created to collect run-off water from carparks, which meant that petrol interceptors were largely unnecessary.
“These kinds of approaches,” says Sexton, “allowed the contractor to keep his price down, and at the same time, it demonstrated to the OPW that we were taking a better environmental approach to developing the site.”
Paul Stewart says that making a building both aesthetically pleasing and environmentally sound can sometimes be difficult. Extensive glazing is a frequent requirement, both to provide the right look and to deliver daylight into office spaces. “But that isn’t necessarily the most environmentally friendly to design or build,” he says.
In large office buildings, the cooling load is typically heavier than the heating load, which is why conventional developments invariably require large air conditioning systems. In Tipperary, both buildings are naturally ventilated. The system is facilitated by windows at high and low level. The top hung sashes are controlled by the building management system (BMS) linked to temperature and CO2 sensors. These facilitate automated indoor environmental control, night purging and summer cooling. There’s also sufficient flexibility for staff to over-ride the system and open or close windows as they require. Only meeting and conference rooms, because of their higher occupancy levels, require mechanical ventilation.
The natural ventilation strategy not only reduced the M&E bills for the project, but also makes both buildings much cheaper to cool.
The use of precast concrete, in addition to delivering a greener supply chain, also allowed the building to benefit from thermal mass. “It gave a very high quality finish internally,” Sexton adds, “and good reflectance.” Also, by deploying this fair-faced concrete finish throughout the building, the need for ceilings was eliminated in all but circulation areas and conference rooms.
Single leaf block fitted with external insulation was deployed throughout the project. “It’s easier, quicker and more cost effective to build,” says Sexton. “And by having a good rational structure, you have a better chance of keeping a very high standard.”
Simplicity and rationality were also central to the decision to rely on wet plastered blockwork internally to deliver air tightness. This was supplemented by tapes and seals at key junctions. The project achieved an airtightness result of 1.73(m3/hr)/m2 at 50Pa, which is exceptional for a naturally ventilated building with over 500 opening sashes.
Quality onsite is also fostered by the contractor’s training policy, which, Paul Stewart explains, is built around an annual appraisal process in which management sits down with each individual worker and builds a training programme to match his or her career path. For employee engagement purposes, he points out, it’s vital that everyone on the team has a say in what training will be given and when.
“You want everyone to be engaged in their own future,” he says. “If they’re making their own decisions and are working on items they chose themselves, they’re happier, plus you get the best out of them.”
He’s also keen to say that the drive for sustainability and the drive to keep costs down are mutually reinforcing imperatives. “At the end of the day, people are spending a lot more time considering lifestyle costing, the true cost of a building, that’s from an economic perspective as much as it is from a sustainable view.”