John Hume Building, National University of Ireland, Maynooth

Design Patterns

Daylight and Solar Energy: Daylight was a major consideration during the design process. It was maximised through the use of roof lights, borrowed light in the concourse and curtain walling at one end of the atrium. K Glass was used throughout the building, reducing the heat loss and energy consumption. Low energy lighting was also used throughout the building, as well as T5 light fittings in the classrooms and offices, and low energy down lights in the lecture theatres. All areas were fitted with timer cut-offs to prevent lights being left on at night. Brise Soleil on the south façade reduce the solar gain within the interior, improving thermal comfort and allowing spaces to be naturally ventilated. The deep loggia at upper levels shade the offices.

Natural Ventilation: The atrium plays a central role in the natural ventilation strategy that has been vigorously pursued throughout this building. Its height makes it possible to draw vitiated air from the adjacent spaces, which is then exhausted at high level. Environmental modelling for the building predicts that energy use will fall within the lowest band of the Department of Education guidelines and reflects the architect's firm commitment to sustainability The auditorium and lecture theatres use assisted natural ventilation with plenum walls bringing fresh air directly from outside which is then passed over radiators before entering the spaces. These walls are lightweight and appropriately soundproofed and insulated. The low velocity extract ducts from the two smaller lecture theatres are expressed as they rise through the main atrium. In a similar way the natural ventilation and heating within the theatres is dramatically expressed by slatted timber panelling, hanging ceilings and slots below the tiered seating- all designed to allow the passage of air. Externally high level copper louvers are set flush into the copper panelling of the theatres. A high level of co-ordination during detailed design overcame acoustic and fire safety issues inherent in the natural ventilation strategies adopted. The integrated system of inlet and outlet dampers is controlled by a comprehensive Building Management System. The main lecture theatres are naturally ventilated with assisted mechanical extract which switches on as air quality is reduced through increased occupancy. The air is pulled through voids in the suspended ceilings at very low velocities to minimise background noise. External air is brought in through plenum walls, controlled by mechanical dampers, and pre-heated prior to entering the space- by radiators and heating coils. The plenums have been designed, in consultation with other specialists, to minimise air-borne sound and condensation risks. The distribution maximises the fresh air delivered directly to the occupants.

Sustainable Elements and Building as 3-D Text: The Design Philosophy of the Building from the outset was to deliver a building which was totally naturally ventilated utilising sustainable and energy efficient systems and employing a holistic approach to the integration of the building, its systems and its users. Natural ventilation has been utilised to improve the energy efficiency throughout the building. All occupied spaces from the relatively low occupancy areas to the 450 seater main auditorium are fully naturally ventilated through either single sided, cross ventilation or stack ventilation. The Overall Ventilation Strategy is as follows: - Rooms that are less then 6m in depth are ventilated by means of single side ventilation using operable windows. - Rooms that are greater than 6m in depth are ventilated be means of cross ventilation and the use of atrium to create a natural stack to encourage the air across the occupied space. Fresh air is introduced by means of external louvres with automatic thermosat-controlled motorised dampers and manually openable windows. The control philosophy for these spaces is as follows: - Building is preheated to 19oC prior to occupancy. - Initial occupancy, radiators are on, with dampers and windows closed. - Fresh air dampers open to allow minimum fresh air into the space. - As internal temperature rises above 19oC, a three port diverting valve diverts heat away from the radiators, thus shutting off the radiators. - If the internal temperatures rises above 22oC, the dampers modulates from 10% open to 100% open at 25oC. - Occupants also have the option of manually opening the windows to improve thermal conditions. - At night, if internal temperature is greater than 21oC and outside temperature, and outside temperature is greater than 12oC the dampers shall modulate to open to provide night cooling, so as to cool down the exposed thermal mass. Cross ventilation is achieved through permanently open acoustically lined shunt ducts between the occupied spaces and the atrium. The atrium is ventilated by means of high level dampers and external louvres at the top of the atrium. The dampers are controlled by temperature sensors are controlled via temperature sensors located within the atrium. A weather station located on the building shall shut atrium dampers during adverse wind and rain conditions. The main lecture theatres are naturally ventilated with the assistance of an element of mechanical extract, the extract fans are switched on as air quality is reduced through increase in occupancy. External air is brought in through plenum walls behind the external copper cladding and pre-heated prior to entering the space- over radiators towards the front and heating coils laid in the undercroft of the the tiered seating towards the rear of the lecture theatre. The distribution of air maximises fresh air arriving directly to the occupants. The plenums have been designed, in consultation with acoustic and other specialists, to minimise air-borne sound, air borne fibre/ particles and condensation risks. The plenums are fitted with mechanical dampers to control the volume of air. Air is extracted mechanically through voids designed into the supended ceilings. Air is extracted at very low velocities to minimise background noise. Extract ducts are expressed in the atrium space. The control philosophy for the Lecture Theatres is as follows: - Building is preheated to 19oC prior to occupancy. - If CO2 sensor indicates that air quality is lower than set point. - Fresh air dampers open to allow minimum fresh air into the space. Extract fans operate at minimum set point. - As internal temperature rises above 19oC, a three port diverting valve diverts heat away from the heat emitters, thus shutting off the heat emitters. - If the internal temperatures rises above 22oC, the dampers modulates from 10% open to 100% open at 25oC and extract fan modulates from minimum flow rate to maximum flow rate at 25oC. - If the CO2 sensor indicates that the CO2 concentration is higher than the set point the CO2 sensor overrides the air temperature control to ensure that there is adequate fresh air within the space. The Natural Daylight & Lighting Strategy is as follows: - Natural daylight has been introduced through the atrium and external glazing. Natural light enters the atrium itself through 4no. rooflights at high level, borrowed light at concourse level through the use of large areas of timber screens and full height, 4 storey, curtain walling at one end. - Low energy lighting is used throughout the building, with T5 light fittings used in the classrooms and offices and low energy down lights used in the lecture theatres. - Brise Soleils have been used on the south façade at level 1 and 2 to reduce the solar gain within the space, improving thermal comfort and allowing spaces to be naturally ventilated. - K Glass has been utilised within the building, reducing the heat loss and respective energy consumption from the heating plant, through permanently open acoustically lined shunt ducts between the occupied spaces and the atrium. Design criteria The design criteria for the John Hume Building was as follows: Achieving as a minimum – and improving on - an energy rating for an Energy Efficient Building under the Department of Education’s Energy Performance Indicator. By this standard an Energy Efficient Building has an EPI of 70 to 100 kWh/m2/yr – the building complies with and will exceed this performance. Achieve a minimum – and improving on - BRE Standards for Naturally Ventilated Spaces. By this standard temperature not to exceed 25oC for 5% of occupied year and 27oC for 1% of occupied year - the building complies with and will exceed this performance. Achieving as a minimum – and improving on - an energy rating for an Energy Efficient Building under the current CIBSE Energy Performance Yardsticks. Under real conditions an energy rating of less than 190KWh/m2/yr is regarded as good practice for third level buildings under the CIBSE Energy Performance Yardsticks. The building complies with and will exceed this performance. Air Quality parameters have also been established for the lecture theatres, once the carbon dioxide rises above 1000ppm the natural ventilation system will react to ensure that the lecture rooms have adequate fresh air Performance monitoring Energy The energy levels will be monitored via the BMS, the following meters are connected to the BMS which allows easy tracking of energy consumption within the building: Gas Meter ESB Meter Water Meter This will allow the BMS and hence building manager to calculate the consumption rate, daily usage, current month usage and previous month usage of the energy providers within the building. Through this the actual energy usage can be compared to the predicted energy use for the building. Also connected to the BMS are the run hours of the main plant items such as the LPHW pumps, HWS pumps, AHU fan and all extract fans. Through this the profile of the plant items can be reviewed over a 24 hour period. This allows the Building Operator determine that the plant is running as per the design and is not operating during unoccupied periods. Air Temperature/ Air Quality Air Temperature Sensors and CO2 sensors are located within the occupied areas where appropriate to ensure that air temperature and carbon dioxide stays within the parameters set out in the design. Conclusion Ultimately what was achieved, is a high occupancy building of a type which would normally require either air conditioning or at the least, air handling, with it’s associated plant and energy usage – designed out. The building will achieve and exceed BRE Standards for naturally ventilated spaces and also achieve and exceed current CIBSE Energy Performance Yardsticks – resulting in an anticipated saving of 145 KWh/m2/yr or 140 tonnes of CO2 emissions a year. Opportunity for visual expression of the natural and mechanical systems employed, both internally and externally (louver banks, large coloured ducts running up the concourse walls) gives an awareness of ‘green’ design and energy saving- to the client, students and also to the general public. Continual participation in the operating and monitoring of these systems by the client and Design Team adds to the level of awareness and education. A process of detailed monitoring of the performance / energy consumption of the building, in conjunction with the client, is currently in train to allow comparison with the predicted levels of energy consumption. Readings from both localised sensors positioned in all spaces, as well as data analysis from the ‘intelligent’ Building Management System taken over a full calendar year, allow for fine tuning or re-setting of controls as necessary to ensure the optimum performance of the building – while also engaging the client to ensure a ‘shared’ learning experience.