Energy

One outcome of the climate agreement is a tailor-made roadmap that will be developed for social real estate, such as buildings of educational institutions. The UT is busy drawing up a UT specific energy roadmap for its 60 buildings, which will be ready this summer. This energy roadmap shows the state of all buildings: which measures can still be taken to improve energy usage, what energy savings can be achieved and what the associated costs are. This way, a roadmap is created that indicates the steps the UT can take to achieve the goals set out in the climate agreement.

WHAT EXCACTLY IS AN ENERGY ROADMAP?

All Dutch universities have agreed to map out the energy consumption for their own real estate portfolios. Therefore, they are creating energy roadmaps. For each building, data is collected such as the building's function, year of construction, previous renovations, operating hours and the presence or absence of PV panels. In addition, specific information is entered about the insulating value of the building's shell (floors, walls, windows, doors and roofs) and energy and gas consumption for cooling, heating, ventilation, water heating, lighting and equipment.

Royal Haskoning DHV has developed a model which then calculates the various energy saving measures required to achieve the desired result. Examples of these measures include: roof, facade and floor insulation; replacing existing windows with double and triple highly efficient insulating glass; applying PV panels; realizing district heating system; heat recovery ventilation systems; installing presence detection; selecting energy-efficient devices and installations; installing LED; and making buildings including its devices energy demand controlled.

THE NEXT STEPS

Once the UT has collected all data for its 60 buildings, a plan with various scenarios will be made. These scenarios show exactly how much energy all measures save and what the investment costs are. The energy roadmap will be linked to the Long-Term Housing Strategy (LTSH) and the Multi-Year Maintenance Planning (MJOP) which are part of the Real Estate & Maintenance department (from Campus & Facility Management). This way, sustainability of the UT buildings will increase. As soon as the energy roadmap is completed and the measures are identified, this information will be updated.

ENERGY CONSUMPTION

The graph below shows the campus’s energy consumption over the period from 2005 to 2019. The consumption of electricity, natural gas and district heating has been translated into Gigawatt hours (GWh). The long-term agreements with the government to cut energy consumption by 30% over the course of 15 years are represented by the grey line, which reflects an average annual improvement in energy efficiency of 2%. We achieved the target consumption levels as early as 2014.

Energy usage and reduction target

The remarkable increase in energy consumption in 2010 can be explained by the fact that several new buildings were commissioned that year, and in the transition phase, both the old and the new buildings required heating and electricity.

The increase in gas consumption can be explained by the fact that it is better for the steam boilers used to humidify the air to remain in stand-by mode than switched off, as this would lead to severe corrosion and wear.

Until now, energy saving measures have focused mainly on making the buildings more energy efficient. Users, however, can also influence energy consumption. The next step is to raise awareness, so that people will become conscious of how they use lighting, heating and cooling systems, as well as all other devices.

ENERGY EFFICIENCY PLAN

In the context of the Long-Term Agreement on Energy Efficiency, the university has drawn up an Energy Efficiency Plan (EEP), which is updated every 4 years. The EEP provides insight into the university's energy situation and energy saving options.

As part of the EEP, the university is currently working on implementing an n Energy Management System. Campus & Facility management is responsible for all building-related energy consumption, whereas the faculties are responsible for non-building-related energy consumption, such as consumption by user equipment, and LISA is responsible for the energy consumption of the central server rooms and ICT equipment.

The cold circulation system is a large basin measuring 10 meters deep and 36 meters wide that holds 10 million litres of cold water, which is used during the day to cool the connected buildings and research equipment. The chillers mainly cool the water at night, because the water temperature is naturally colder then, which saves a lot of energy.

On top of that, it also saves costs, because the night rate for energy is lower than the day rate. The cool nighttime climate and air-cooled chillers join forces to cool the water down to approximately 8 to 10 degrees Celsius. The cold water is heavier and is added to the bottom of the basin, whereas water that has been pumped through the buildings returns with a temperature of about 18 degrees Celsius and is added to the top of the basin. The large temperature difference creates a so-called ‘thermocline’, which means that the warm and cold layers remain separate and that the warm water insulates the cold layer of water, as it were. The cold circulation system has a cooling capacity of 11 MegaWatts, which is equivalent to more than 70,000 refrigerators. The cold circulation system also acts as a storage buffer in the event of a major fire. Currently, de Horst, Carré, the Nanolab, the Waaier, the Ravelijn, Hal B, the Zilverling, the High-pressure lab, the Seinhuis and the Teehuis are connected to the cold circulation system. 

The system contains more than 10 million litres of water, which has to be treated in order to prevent corrosion and deposits on the cooling system, which we do by means of a helophyte filter. A helophyte filter uses helophytes to treat wastewater up to a point at which it is no longer harmful to the environment. Helophytes are plants that grow above water but take root in very wet soil, and they are capable of transporting oxygen to their roots themselves. 

Behind the Horst, there are two fields that have been covered in gravel, sand and anti-root foil, on which we have planted reed plants. The dirty water flows onto the field on one side, before sinking through the gravel. In the soil, the waste materials are converted into nutrients for the plants in the filter. When it leaves the filter, the water is clean enough to return to the cold circulation system.

The UT has several chillers to make sure that the water used to cool the buildings and research equipment is cold enough. The centrifugal chiller commissioned for this purpose in 2014 is certainly an advanced machine, with a capacity of 2.8 Megawatts. The centrifugal chiller is paired with several heat exchangers on the roof, which let it discharge the heat produced by the system. At an outside temperature of 8 degrees Celsius, the chiller works ‘for free’, because the heat exchangers (condensers) provide sufficient cooling, to the point that no mechanical cooling is required. This is also known as free-to-air cooling. On top of that, this chiller boasts an extremely good Coefficient of Performance. A machine with a COP of 3.5 requires 1kWh to produce 3.5kWh worth of cold. Our centrifugal chiller can reach a COP of anywhere between 7 and 10. Using the heat exchangers on the roof, the chiller can also discharge the heat it produces, resulting in a combined COP of 7, which is certainly above average. The older chillers are only used in extreme heat and are primarily used at night, because it costs less energy to cool the colder evening/night air than the warm daytime air.

In the Carré, Nanolab, Zuidhorst and Meander buildings, heat exchangers extract energy from exhaust gases. A condenser installed in the outlet of the steam boiler heats the water in a large water basin, thus pre-heating cold drinking water, for instance, with heat that would otherwise have disappeared through the chimney. This approach also reduces limescale deposits and corrosion (rust), improving yield.

The air treatment unit installed in the Spiegel building features a heat recovery system. In wintertime, extracted indoor air is much warmer than outdoor air, which means that a heat exchanger can be used to transfer the heat from the extracted (indoor) air to the incoming outside air, which is colder. This prevents heat loss, and the process can simply be reversed in the summer.

Setting up systems to be demand-driven ensures that no more energy is consumed than strictly necessary. Carbon sensors and heat sensors monitor quality and adjust the inflow and outflow of air accordingly. An example: One of the buildings on campus always used to be particularly warm, because 90°C water, destined for the heating system, would flow through the pipes all year long. Now several changes have been made to the system, hot water only flows through the pipes when there is a need for heat: when the heating is switched on.

Study areas and lecture halls are only heated or cooled when they are in use, in addition to being pre-heated when necessary. To do so, the climate control system retrieves information from various booking and scheduling/timetabling systems. Now, study areas are only lit when they have been booked, and unbooked rooms are not heated.

To prevent heat loss, the pools are covered when they are not in use. The pool used for swimming classes is even equipped with solar slats, which block outbound heat whilst allowing incoming heat (from the sun) to pass through.

Swimming pool and shower water heated by solar collectors

The pool and shower water is heated by 40 solar collectors. The panels are located on the roof of the changing room, the current boiler and the rooftop terrace.

Solar water heaters for Sports Centre

The Sports Centre boasts two solar water heaters with a combined output of 52 GJ per annum. Gas-fired supplementary heating - amounting to 1280 m3/year, which is comparable to the annual energy consumption of a single household - is used to meet the entire heating demand.

When a lamp has to be replaced, it is replaced with an LED. If possible, it is also linked to a motion sensor (not in laboratories for safety reasons). AN annual budget has been reserved in the maintenance plan for this purpose.

In recent years, the UT has switched to using dimmable LED outdoor lighting. Approximately 80% of all lampposts are now equipped with LEDs. Now, it is possible to configure light intensity for each road, intersection, cycling path or car park individually, and lighting systems need not always be set to 100%. Safety is paramount, of course, but adjusting lighting intensity can help us save energy and prevent unnecessary light pollution.

We have the habit to leave the light on even though it may not actually be needed. In the rooftop structure of the Carré building, which housed the technical room, the lighting used to be on 24 hours a day. This has now been changed, and the lights are switched on and off automatically. The lighting system in the stairway of Ravelijn has also been modified. It is important that the stairwell be illuminated 24/7, but switching on only one of the two fixtures is enough to comply with safety requirements and save energy at the same time. Such measures have a visible impact on energy consumption for public lighting.

A climate facade is a glass facade placed around a building like a second shell. In 2000, such a facade was installed on Spiegel. The sun heats up the air in the space between the facade and the building, creating a heat buffer that reduces the demand for heat in wintertime and keeps the building comfortable in spring and autumn. The top of the facade is equipped with flaps, which are opened when both the outdoor and the indoor temperature at least 20°C. All ventilation is based on natural mechanisms: warm air rises and cooler air flows into the facade at the base of the building. In addition, the building is also equipped with blinds to keep as much heat out as possible on hot, sunny days.

The air exchange system is controlled by carbon sensors. When carbon levels remain below a certain standard, e.g. when a room is not in use, less new air is supplied when not strictly needed, resulting in less unnecessary energy consumption. Carbon sensors also benefit comfort by regulating the indoor climate: although the Working Conditions Standard specifies a limit of 1200ppm, 800ppm is optimal.

Providing insight into the consumption of various devices increases awareness and changes how they are used. At the UT, a wide range of user devices are equipped with sensors.

The aim of this pilot was to investigate whether Internet-of-Things devices could be used in new construction and renovation projects. Belimo energy valves can control, monitor, measure and secure control valves connected to the Bacnet IP network. This pilot was successfully tested in Horst T1300.

Guaranteeing user comfort whilst minimizing energy consumption and making climate quality and energy consumption both visible and measurable where the starting points for a pilot with a new control and optimization strategy. This successful pilot is currently up-and-running in various buildings on campus, including Waaier (room 2) and Vrijhof (Audio room, Amphitheater and Agora). The new strategy has led to a noticeable improvement in comfort and draught problems have disappeared.

Phase Change Materials, a type of thermal battery, are used to store heat and cold, so that it can be used at a later date. PCMs behave like thermal batteries and are therefore highly suited to acting as heat/cold buffers.

In the basement of Zilverling, there is an air treatment unit that consists of a water cooling battery, a PCM cooling battery, a supply fan and an exhaust fan. Phase Change Materials are non-combustible, inorganic thermal salts whose phase change from solid to liquid and vice versa is used to store and release heat/cold. When it absorbs heat from the environment, the material melts, before solidifying again when the heat is released.

A fume cupboard is an extractor hood with an adjustable opening (sash), limiting the user’s exposure to harmful substances as much as possible. At its highest setting, the fume cupboard has an extraction rate of 650m3/hr, compared to a rate of 250m3/hr in the lowest setting. This demand-driven extraction system was implemented in Carre in 2018.

The renovated Technohal features 624 solar panels on the roofs of the side section, partly funded by an SDE subsidy.