Temple Quay House
4.3 The reliance upon natural ventilation and cooling through these methods obviously depends upon the external air temperature being less that the internal one, if not, then there would be little perceived benefit. There are occasions when, in peak summer, the external air temperature will be so high that it will provide no measurable cooling effect to the interior. So the potential internal heat loads, people, computers etc would make the environment uncomfortable for productive operation.
4.4 This is why the building has a second line of defence. The raised floor, which provides a logical route for all the power and data outlets for the building, also acts as an air plenum. An air plenum is a well sealed under floor void which is pumped full of cooled filtered air (cooled to 19 Degrees C) this air is then let out into the office areas via a series of low velocity air diffusers. They are round grills set in the floor at regular centres, placed to avoid being directly under a person’s chair. These grills allow the cooled air to form a pool of air around the occupants, which displaces the warmed air into the atrium and thus will cool the space like an air-conditioned building.
5. Energy Issues
5.1 The system is in itself is quite a high consumer of energy, it is the ability of this design to call upon this facility only when it is required, that can save significant amounts of energy. If so desired the DETR could running this under floor cooling system 24 hrs a day, 365 days a year. They would however see no reduction in energy running costs compared to an air- conditioned building. This option to only call upon this system when the building detects, through a series of temperature sensors, that the internal temperature is rising, is described as the “mixed mode of operation”. Mixed in the ability to rely on natural ventilation and cooling when external air temperatures allow, and to use the under floor cooling system when they do not.
5.2 The air delivery system relies upon having uninterrupted air flow across the office space and into the atrium. This placed a constraint upon the provision of office cells on the floor plate. Requiring a general move toward open plan offices. Obviously this caused much discussion within the staff. However, it was encouraging to see the reaction of most who thought the principle of green offices was worth supporting and rose to the challenge of different working conditions. As we moved closer to the completion date of the end of March 2001 a number of staff visits to the new offices and the reaction was overwhelmingly positive.
5.3 This method of mixed mode cooling is only one way of reducing energy consumption at the new DETR building. Lighting, accounts for the largest single source of energy consumption for offices. This fact is borne out when we walk around offices in any city at night. We observe empty office buildings with floor upon floor of lit offices when the staff are long since gone. We have employed “intelligent “ lighting and controls. The lights are movement linked so the will come on and switch off when no movement by staff is detected, i.e. when they have gone home. They are also daylight sensitive, and will self dim when the natural light form outside provides sufficient lighting levels. They can also be manually overridden, if required, but this will obviously effect their energy consumption. To ensure that the right lights were selected for the job, and that its self-dimming and movement detection were effective and not annoying, a prototype was test driven in the own co location office for 6 months before specifying the product for use in the building.
5.4 These are two of the most important energy saving measures employed for the DETR but in addition we have sought to use other energy saving devices. These include providing most of the common facilities for the building on the ground floor, such items as conference rooms, restaurants, shops, central reprographics room and post room etc. These higher heat producing areas can be cooled more effectively by their adjacencies than if they were spread across the building. “Hot Spot” rooms have been provided on all the floors for the location of most of the photocopiers. These high heat producing equipment need to be additionally cooled, so by locating them together we can reduce their heating effect to the office areas and more economically cool just the room they are in. We also are collecting rainwater from the atrium glass roof to flush the toilets on all floors. In broader energy saving terms, the provision of changing facilities for staff with showers and clothes drying room encourages staff to use their bicycles to come to work.
The whole package of measures allows the DETR to effectively run a building which consumes significantly less energy than a normal air conditioned building. These measures will only work however, if the occupants work with these measures not against them. Any new building will take a period of readjustment before staff will be entirely happy.
6. Building Management Systems
6.1 The effective monitoring of a building of this design is vital if we are to maintain a good working environment for the staff whilst at the same time maintaining the building’s “green credentials”.
6.2 A computer based system has been designed and installed to control the heating, ventilation and air conditioning systems. The system consists of outstations located within control panels which provide the major interface between plant and equipment. The outstations contain sufficient local software and data storage capability to fulfill operational requirements. The outstations are connected to a central station via a communications network. The central station consists of:
- Central processing unit
- VDU with dedicated keyboard with access level control and dynamic graphic unit
- Printer for hard copy data and graphics
- Facilities for transferring bulk storage to either disc or tape.
7. Facilities Management
7.1 FM services are provided by Aqumen who manage a facilities and maintenance team of 15 staff. A key element of their brief is to ensure that the building’s green credentials are maintained and monitored to ensure that the latest targets set down by the government on energy consumption and waste re-cycling are being met and, where possible, exceeded.
In order to achieve this Aqumen’s service levels fall into five activities:
Monitoring energy consumption
Monitoring CO 2 emissions, waste recycling levels and water consumption
Submission of energy efficiency measures
Provision of Management Information on water and energy consumption/efficiencies, CO 2 emissions, waste and waste recycling.
To achieve certification to ISO 14001 within 18 months of the start of their contract
7.3 The task of keeping the building green is only just beginning. The building has only been fully occupied since June 2001 and the Building Management System is still being fine-tuned to work with the vaguaries of the Bristol climate. In addition, the FM team must look at all their processes asking - Why do we do it (?) and, How should we do it (?).
