Real energy reductions in real buildings
The European Union is committed to reducing energy consumption in the built environment. As heating, ventilation and air-conditioning systems (HVAC) account for around 11% of the total electricity consumption in Europe (according to figures from the EC Joint Research Centre), these systems are an important element in the EU’s commitment. In this article, we find out more about two specific aspects of HVAC energy-efficiency; both focus on how important it is to understand how commercial buildings operate in real life as the first step on the road to reducing energy consumption.
Firstly benchmarking of in-use energy data. To understand, improve and legislate on energy consumption in commercial buildings, a proper assessment of existing energy performance of HVAC components is vital. This is where the iSERV project comes in. Funded by the EU’s Intelligent Energy Europe, iSERV provides continuous monitoring and benchmarking of HVAC systems. Participants will be able to link energy use at HVAC component level to the activities served. To find out more, we interview Dr. Ian Knight, Reader at Cardiff University and iSERV project coordinator.
Dr. Knight has been involved in research into the performance of buildings and building elements for over 20 years, particularly in the area of reducing carbon emissions from the built environment. Dr. Knight holds a BSc(Hons) degree in Fuel and Energy Engineering and a Physics PhD.
Another area of focus for the EU is new buildings that overall consume almost no energy. These nZEB or nearly zero-energy buildings could be viewed as an important part of the solution to improving HVAC energy-efficiency. EU Directives already require that new buildings occupied and owned by public authorities must qualify as nZEB buildings by 2019, and that all new buildings must be nZEBs by 2021. But unless designers remember to ‘keep it simple’, nZEBs will not provide a simple solution to reducing energy consumption.
We hear more about nZEBs from Prof. Dr. Jarek Kurnitski from SITRA, the Finnish Innovation Fund and at Tallinn University of Technology. Professor Kurnitski has been involved in working to improve the energy efficiency of the built environment for many years. Before coming to SITRA, he was Professor at the Helsinki University of Technology, where he led the Indoor Climate and Energy Performance Centre research. He is also a Vice-President and Board Member of REHVA, The Federation of European Heating and Air-conditioning Associations.
Grundfos met both men at the REHVA Annual Conference and Meeting 2012 on HVAC Technology and Energy Retrofitting, held in Timisoara, Romania.
iSERV – serving up continuous monitoring and benchmarking
Dr. Ian Knight had been involved in previous EU projects that indicated possible savings of up to 60% in individual HVAC systems with the help of detailed in-use energy data. The iSERV project (‘iSERV’ was derived from ‘i’ for Inspection and ‘SERV’ for Services, which is what HVAC systems are commonly referred to as) was created with funding from the EU’s Intelligent Energy Europe programme to quantify the existing energy performance of HVAC components and systems as achieved in practice. The Energy Conservation Opportunities (ECOs) uncovered will then be made freely available. The aim is to contribute to reducing the total EU electrical energy use by around 2%.
There is a lack of real life energy use data for HVAC system components. iSERV has been designed to produce a large dataset of sub-hourly energy use in European HVAC systems and their components.
Dr. Ian Knight
Dr. Knight, how will iSERV benefit participants and others?
IK: iSERV addresses the problem of improving the energy performance of HVAC systems in EU buildings in practice. We have developed the most straightforward process of entering buildings to the iSERVcmb database using the data entry spreadsheet, which is designed to link together in one place all the information about HVAC system components.
Participants need only enter the required data including:
- Consumption data on HVAC system components, sensors and utility meters
- Information regarding the floor area and activities served
- Ongoing sub-hourly data at least for the chiller, recorded over a full year.
With iSERV we now have the chance to look at the detail of the energy consumption of HVAC systems in buildings.
Dr. Ian Knight
The data collected by the iSERV project will be used to derive initial benchmark energy use ranges for the energy consumed by HVAC components servicing specified end-uses, areas and hours-of-use. This will enable bespoke benchmarks for, and a clearer understanding of, individual HVAC systems. At present we are recruiting HVAC system owners, operators and system or component manufacturers etc.
Will participants be able to gain a better understanding of their systems?
IK: Yes, as the data increases reports will begin to include comparisons with other compatible systems. This will also include reports on the bespoke performance of their HVAC systems and targeted feedback on potential energy conservation opportunities (ECOs) for their specific system.
What about long-term benefits for participants?
IK: Understanding and managing their HVAC energy consumption more effectively. Understanding the causes of variations in HVAC system energy consumption in similar systems, which will deliver benefits such as:
- More confidence in investment in improving the energy efficiency of poorer performing systems
- Better choice of replacement components
- Financial benefits from more focussed investment in energy efficiency that is also easier to justify
- Greater savings than are possible from inspection alone.
IK: There has been a lack of information on which to base policy decisions and future legislation regarding achieving energy efficiency in HVAC systems in the EU. This situation is now changing. The project hopes to contribute towards returning control over the delivery of energy savings to the key players in the sector, so that it would not matter how you reach the required energy use targets provided you can demonstrate that you have done so through the monitoring. This would allow innovative techniques and approaches and acknowledge that all parties can play a role in highlighting good performance and helping move towards the near Zero Energy Buildings (nZEB) required for 2019 onwards.
All interested parties who wish to participate in the iSERV project can visit the project website at http://www.iservcmb.info/.
Keep it simple: operating nZEB buildings
Designing nearly zero-energy buildings that real people can operate
The European Union’s Energy Performance of Buildings Directive (EPBD) requires that from 2019 onwards ‘all the new buildings occupied and owned by public authorities are nearly zero-energy buildings’ (nZEB) and by the end of 2020 ‘all new buildings are nearly zero- energy buildings.’ In this article we get some answers about where nZEB buildings are right now.
Professor Kurnitski, what needs to be taken into account in the optimal energy management of nZEB buildings?
JK: In practice there are two types of nZEB buildings. On the one hand there are very complicated buildings that are not easy to operate, which tend to have complicated ventilation and cooling systems, mostly hybrid systems. For example, nZEB buildings designed with natural ventilation with limited controls often come to rely on occupant behaviour in opening and closing windows, blinds etc.– and that leads to less than optimal usage, incorrect operation and wasted energy.
On the other hand, there are buildings that are like normal buildings when it comes to operation. The Environmental Centre building in Helsinki is an example of this, with one borehole cooling system and a simple ventilation system, so it is not much more complicated than a conventional building. I believe that systems like this will be very important in the future. We should remember that somebody always has to be able to install, balance, operate and maintain the systems in nZEB buildings, so keep it simple and use high efficiency components and systems.
We need to put more effort into designing buildings that are simpler to operate
What about the role of pumps and other HVAC components in nZEB buildings?
JK: Pumps, fans and other HVAC components are important. If these components are designed to operate in a simple system, then it is particularly important that they are high-efficiency components. One major trend in the design of nZEB buildings is towards low pressure, low velocity, sometimes self balancing systems that also deliver high efficiency.
Why do nZEB buildings fail to live up to expectations?
JK: One reason is that they can be too complicated. Another factor is that the design can be too optimistic. Also, what we are seeing are unexpected factors such as office appliances that are in fact dominating in the energy balance of the building.
What we are now seeing with nZEB buildings is that that office appliances have in fact become a major component in the energy balance
For an nZEB building in Paris, France, measured energy use showed that office appliances consumed twice as much energy as the designers had allowed for.
Has your research identified common technical features of nZEB commercial buildings?
JK: Yes, there are some general features that are common. On an overall level, nZEB buildings combine demand reduction with effective systems and on-site renewables. In general they typically share features such as:
- Water based distribution systems for heating and cooling with better energy efficiency than air based systems
- Wide range of energy sources such as heat pumps, District Heating, bio-CHP, solar PV and thermal
- Heat recovery ventilation, often demand controlled, by centralized or decentralized systems
- Free cooling solutions combined with mechanical cooling via evaporative or ventilative cooling etc.
- High efficiency heat recovery
- Optimized building envelope and effective external solar protection
- Utilization of thermal mass and other passive measures.
What else is needed for nZEB buildings to a become more common place?
JK: Building regulations remain the major driver here. Energy performance targets established by e.g. the EPBD (Energy Performance of Buildings Directive), and set in national building codes are important. We need to bear in mind that there is less than seven years until new public buildings will be required to be nZEB buildings under EU regulations. Energy performance improvements will also happen for existing buildings, but not yet to nZEB performance level as this is not realistic for existing buildings.