North Yorkshire – United Kingdom
Using passive design features to reduce energy consumption in a new build officeBackground
The opportunity arose for North Yorkshire County Council to purchase a new build administrative office at short notice. By working closely with the building developer, the Council was able to alter the original building plans in order to incorporate several passive design features. These features result in significant reductions in energy cost, energy consumption and CO2 emissions, as well as an improved working environment for staff.
For example, the developer proposed the use of a DX-VRF heat pump system to provide heating during cold months and comfort-cooling during summer months. However, the Council suggested the use of the Windcatcher™ natural ventilation system instead, reducing energy costs by around £70,000 (in net present value terms) and CO2 emissions by 333 tonnes over 25 years.
The Council also incorporated several other energy and water efficient features into the building design, including Sunpipes™ to utilise natural daylight, solar shading, waste heat recovery and rainwater harvesting. The Council also plans to install a wind turbine in the future.
This image shows a similar building by the same developer (actual office under construction, due to be finished July 2007).
Building details |
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| Type of building : |
New build administrative office |
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| Year of construction/ Floor area/ Operating hours : |
2007(under construction) / 1594 m2 / 11.5 hrs per day, 255 days per year (5 days x 51 weeks x 11.5hrs = 2,932 total operational hrs) |
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| Heating and cooling / measures installed |
Natural gas heating system (radiators) and Windcatcher™ natural ventilation system. |
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| Energy label/CO2 emissions |
The projected Display ratings for energy consumption, CO2 emissions and water use are significantly improved thanks to the new design features :
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ProjectDescription |
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| Aim |
To improve the basic building ‘offered’ by the developer, making it more sustainable and reducing energy consumption, and thus CO2 emissions.
_ The new design features also aim to improve the internal environment for staff. The project provides an opportunity to showcase low energy technologies and passive building design to the local community. |
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| Key points |
Measures to be installed
Thanks to the Council’s input to the building design, several exciting energy efficient measures are being installed in the new building, including :
- Windcatcher™ natural ventilation system, which promotes a healthier working environment, potentially increasing staff productivity ;
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_ The Monodraught Windcatcher™ system provides natural ventilation by encapsulating wind at roof level and carrying it down to the rooms below through a controlled damper arrangement (photos provided courtesy of Monodraught Ltd).
- Sunpipes™ to bring natural daylight into the top floor area, and together with daylight-linking and occupancy sensors, reduce electricity for lighting significantly ;
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_ Sunpipes™ provide natural daylight inside buildings and eliminate the need to use electric lighting during daylight hours (photo provided courtesy of Monodraught Ltd).
- Low energy lighting ;
- Solar shading to windows on the south facing elevation to reduce heat gain in the summer months ;
- A waste heat recovery system designed to collect and use the heat given off by computers in the server room to minimise energy used for heating in the winter. During winter, warm air will be extracted from the server room and passed through a heat exchanger. Fresh air brought in from outside the building will pass through this exchanger and pick up the heat recovered from the stale air. The warmed fresh air will then be ducted into rooms within the building ;
- Intelligent metering, which along with implementation of the Building Energy Management System (BEMS) will allow monitoring and control of energy consumption.
_ Rainwater will be harvested and used to minimise the water requirements of the building. Trees will be planted to provide shade and a comfortable place for staff and visitors to sit outside.
_ The Council also plans to install a wind turbine to provide some of the electrical energy for the building, subject to planning permission. Finance has been approved but the turbine specification was not finalised at the time of writing.
_ Expertise
_ Staff knowledge of sustainable technologies and low/passive energy design was used for this project.
_ Staff learnt of the Windcatcher™ natural ventilation system when the Council’s existing headquarters (County Hall) was surveyed in 2005, with the view to installing Windcatcher™ to improve the air quality for staff. (The good news is that this proposal has now been approved so Windcatcher™ will be installed in County Hall soon).
_ Natural ventilation was considered because the Council has a policy of not installing regular air conditioning, wherever possible. For this project, the Windcatcher™ natural ventilation system provided huge energy, cost and CO2 savings, compared to the heat pump system suggested by the developer (as discussed above).
_ Communication was crucial
A project team was established from within the Council to work closely with the developer and explain the proposed technologies and associated benefits. Regular meetings between the project team and the developer allowed for the exchange of ideas.
_ All Council staff were kept informed of the improvements via the Council’s “Energy Matters !” newsletter.
_ Key drivers for improvements
Being a member of the Display™ Campaign was a key driver that led to the incorporation of energy efficient design features in the building plans. Using Display™, the Council was able to produce a projected Energy Label for the building showing the results before and after improvements. This was very useful in strengthening the business case for the design features.
_ The improvements also tied in well with the Council’s Sustainable Development Policy, and their involvement in the Local Authority Carbon Management Programme (LACM), which is run by the Carbon Trust and provides councils with guidance to help them reduce carbon emissions (note : The Carbon Trust is an independent company funded by the UK Government, that works with UK business and the public sector to cut carbon emissions and develop commercial low carbon technologies).
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| Reason for inclusion as Shining Example |
This project is an example of how the energy performance of a ‘standard’ building can be substantially improved through proactive discussion, co-operation and relationship building between the client and the developer. Despite the limited time available for the Council’s input into the building design, their suggested improvements have resulted in a 40% energy saving. Funding for the improvements was gained by using the Display calculation tool in conjunction with life cycle analysis to present a convincing business case.
_ This project also demonstrates the energy savings that can be made by utilising passive design features, particularly for heating and cooling. |
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Costs&Benefits |
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| Costs &
funding
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Finance for the new building was gained by selling other smaller offices. The additional cost of the passive measures is around £130,000 (< 5% of the total build cost), which was justified using life cycle analysis techniques. The extra money was provided by the Council’s central finance, having considered the business case for the measures.
_ The measures should recover the additional capital outlay in around 12 years from reduced running costs. |
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| Benefits |
The improved building design will save 333 tonnes of CO2 over 25 years, which in yearly terms is equivalent to the annual emissions from 2.4 average UK households.
_ The improvements will also result in a projected 40% reduction in energy consumption, which translates to a reduction in the annual energy bill of £4,230 (at 2006 prices). The building design will also provide improved environmental conditions for staff within the building.
_ Energy consumption and CO2 emissions will be further reduced when the wind turbine is installed for on-site electricity generation.
_ Another benefit of the project is the example it can provide to the local community on how buildings can be made more energy efficient, as well as raising general awareness of energy efficiency. |
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Partners&Roles |
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| Partnership details |
A working partnership was formed between North Yorkshire County Council and the developer, Castlevale Properties Limited, established by the Council’s Finance Director.
_ Advice on the proposed wind turbine was provided by the Intelligent Energy Europe (IEE) project WINEUR (Wind Energy Integration in the Urban Environment), Future Energy Yorkshire, Ryedale Energy Conservation Group and the Council’s Carbon Reduction Manager. |
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Recommendations |
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| Achievements |
One of the key achievements of this project was how the Council managed to overcome the developer’s initial resistance to change by using sound financial reasoning.
_ Monitoring and evaluation
_ Monitoring of energy consumption in the new building will be achieved using intelligent metering and BEMS. The success of the passive design features in reducing energy consumption will be reflected in the energy performance of the building. The impact of the design features on the comfort of the internal environment will be evaluated by staff satisfaction and feedback. |
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| Lessons Learned |
The Council had to make a very quick decision when the opportunity arose to purchase the new build office. By working with the developer and other partners, the Council was able to improve the basic design to produce a building that will consume around 40% less energy. However, the Council noted that in future projects, better results could be obtained by considering the building design in a more holistic manner at the outset. |
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