Timaru Technology Education Centre Building Features

Timaru Technology Education Centre has a number of features designed to minimize energy use. Below is a list of the features and some aspects of their control.

Ventilation

The building is designed to be naturally ventilated. This is achieved by fresh air entering thorough low level windows in the classrooms, passing through ventilation bulkheads to rise and exit out of the high level windows in the design planning area.

This control of the windows is achieved through a combination of weather sensing of outdoor wind, temperature and indoor temperature sensing. When the system is in auto mode, and a class room requires cooling, the windows in that classroom, and the lee window bank in design planning will open to allow airflow through the classroom and design planning space. If the outdoor air is too hot for cooling the AC unit will be enabled.

This system however will only work if the windows are in auto mode.

Other natural ventilation is available through non actuated open-able windows. Additional fresh air is brought in via passive roof cowls when the AC cassettes are running.

Heating

A combination of heating systems has been used. In all class room areas inverter heat pumps will limit energy consumption. The central space has under floor heating, other areas where less heating is required radiant heaters have been used to reduce capital cost.

Air Conditioning

The cassette units in the classrooms are linked to the operation of the windows. This is done to ensure the windows are not open when the AC units are also on, and also to ensure heating or cooling by the AC unit is only done when free cooling or heating is not available from the outdoor air.

AC Heating/Cooling

Assuming the system has the windows closed, either through the BMS control or the manual over ride, and the classroom space requires heating or cooling, then there are two possibilities.

Free Cooling

If in Auto mode the BMS will compare the indoor temperature verses the outdoor temperature and determine whether free heating or cooling is available from the outside, if so then the windows will open and cool the space.

AC Cooling/Heating

If free cooling is not available, then the AC units will be enabled, and will run to the heating/cooling presets which have been set on the remote controls. This will continue until the space temperature requirements as set in the BMS are satisfied, in which case the AC unit will be disabled. Individual AC units set points are not set by the BMS, they are set manually and are not to be available for general use.

The AC units in a classroom will be disabled if the window is in manually open position. If fresh air is required while the AC unit is running then windows with no actuators on them should be opened.

If a room is unoccupied for more than 15 minutes the AC unit will be disabled.

 Ventilation Systems

A large part of the ventilation is provided for through natural ventilation via opening or controlled windows. Each classroom has opening windows. The main design space has automatic windows which are linked to a temperature and wind speed weather station. This weather station allows the high level windows to open when conditions are favorable and cool the building.

A ventilated bulkhead has been provided between the classrooms and the design space to allow natural cross flow air movement from the classrooms to the design planning area where it can be exhausted if required.

Building Management System

The proposed building management system provides a number of operational energy savings and educational benefits to the school. The BMS is also integral to the control of multiple systems to maximize energy efficiency.  The BMS also offers significant educational potential through its interactive display that conventional controllers would not provide.

Features of the Timaru Technology and Education Centre BMS

· Weather station for outdoor air temperature and wind speed and direction. This weather station will be used to control the operation of the air conditioning and natural ventilation systems to minimise energy usage.

· Automated window control based on opening high atrium windows on the lee side of the building if outdoor air temperatures are suitable for free cooling.

· Heating requirements of the floor slab will be determined based on trending the previous week’s weather.

· Lighting internally and externally can be controlled according to daylight sensors to  minimise operating hours.

· Energy monitoring instantaneous overall energy consumption in kWh will be trended.

· A touch screen display will encourage students to understand how the building operates, particularly in terms of how equipment is controlled in terms of weather daylight temperature etc. Energy consumption and its relation to weather patterns and building equipment can be analyzed.

Day lighting and Windows

The building has been designed with large eaves to minimise glare and reduce overheating in the summer. The windows in the design planning areas have been optimised to reduce heat loss through double-glazing in winter, while still allowing reasonable day lighting to the central area.

Solar Hot Water

A small solar hot water system has been proposed to limit energy used in heating water.

Design Planning Under Floor Heating

The under floor heating system may be run on a night rate pre-heat system. The BMS makes a decision as to whether or not to heat the floor slab and how hot heat the floor slab based on trending of the previous week’s weather. The under floor heating then switches of during the day and the thermal mass of the slab provides heat as it cools down.

The under floor system may also run in demand mode in which case it runs during the day to the set point required.

Night purge

If the building requires cooling after hours the design planning windows will open, to allow airflow through the building to cool it down

Energy Efficient Building Shell

High levels of wall, roof and window glazing have been used to insure lower energy consumption and running costs

Lighting and Electrical Systems

Energy efficient long life lamps and occupancy sensors have been selected. This will allow the lights to switch off automatically when not required and the type of lights will reduce overall energy consumption.

Daylight switching of entry lighting will ensure these lights are not turned on when there is adequate daylight within the space.