Zero Energy Buildings _ Rujan Timsina.pptx

Zero Energy Building

1. Zero Energy Buildings: A Critical Look at the Definition P. Torcellini , S. Pless , and M. Deru National Renewable Energy Laboratory Presented by Roll no: Nishan Pandey 066/BME/630 Pikam Pun 066/BME/631 Pradeep Sapkota 066/BME/632

2. Contents: General concept Boundary D efination and Energy flow Principles applied to develop ranking ZEB : Critical Definations and description Advantages and Disadvantages of ZEB Zero energy building versus green building ZEB at CES Conclusion

3. General concept: A zero-energy building, also known as a zero net energy building, Net-Zero Energy Building, or Net Zero Building, is a popular term to describe a building with zero net energy consumption and zero carbon emissions annually. Zero energy buildings can be independent from the energy grid supply. Energy can be harvested on-site—usually through a combination of energy producing technologies like Solar and Wind—while reducing the overall use of energy with extremely efficient HVAC and Lighting technologies.

4. Boundary Defination and Energy flow At the strictest level, a ZEB generates enough renewable energy on site to equal or exceed its annual energy use. At the heart of the ZEB concept is the idea that buildings can meet all their energy requirements from low-cost, locally available, nonpolluting, renewable sources . The following concepts and assumptions have been established to help guide definitions for ZEBs.

5. Grid Connection i s allowed and Necessary for Energy Balances A ZEB typically uses traditional energy sources such as the electric and natural gas utilities when on-site generation does not meet the loads . When the on-site generation is greater than the building’s loads, excess electricity is exported to the utility grid Achieving a ZEB without the grid would be very difficult, as the current generation of storage technologies is limited.

6. Contd … Despite the electric energy independence of off-grid buildings, they usually rely on outside energy sources such as propane (and other fuels) for cooking, space heating , water heating, and backup generators . Off-grid buildings cannot feed their excess energy production back onto the grid to offset other energy uses. As a result, the energy production from renewable resources must be oversized. In many case, excess generated energy cannot be used. We assume that excess on-site generation can always be sent to the grid.

7. Prioritize Supply-Side Technologies Various supply-side renewable energy technologies are available for ZEBs. Typical examples of technologies available today include PV, solar hot water, wind, hydroelectric, and biofuels . All these renewable sources are favorable over conventional energy sources such as coal and natural gas, however, a ranking has been developed of renewable energy sources in the ZEB context .

8. Principles applied to develop ranking Minimize overall environmental impact by encouraging energy-efficient building designs and reducing transportation and conversion losses. Will be available over the lifetime of the building. Are widely available and have high replication potential for future ZEBs.

9. ZEB Energy Supply Option Hierarchy A good ZEB definition should first encourage energy efficiency, and then use renewable energy sources available on site.

10. ZEB: Critical Definations and description A zero energy building can be defined in several ways, depending on the boundary and the metric. Different definitions may be appropriate, depending on the project goals and the values of the design team and building owner. For example, building owners typically care about energy costs. A building designer may be interested in site energy use for energy code requirements. Those who are concerned about pollution from power plants and the burning of fossil fuels may be interested in reducing emissions.

11. Contd … Four commonly used definitions are : Net Zero Site Energy Net Zero Source Energy Net Zero Energy Costs Net Zero Energy E missions

12. Net Zero Site Energy In this type of ZEB, the amount of energy provided by on-site renewable energy sources is equal to the amount of energy used by the building. A site ZEB produces at least as much energy as it uses in a year, when accounted for at the site. In the United States, “zero net energy building” generally refers to this type of building.

13. Net Zero Source Energy This ZEB generates the same amount of energy as is used, including the energy used to transport the energy to the building This type accounts for losses during electricity transmission . These ZEBs must generate more electricity than zero net site energy buildings.

14. Net Zero Energy Costs In this type of building, the cost of purchasing energy is balanced by income from sales of electricity to the grid of electricity generated on-site Such a status depends on how a utility credits net electricity generation and the utility rate structure the building uses.

15. Net Zero Energy Emissions Outside the United States and Canada, a ZEB is generally defined as one with zero net energy emissions. also known as a zero carbon building carbon emissions generated from on-site or off-site fossil fuel use are balanced by the amount of on-site renewable energy production Other definitions include not only the carbon emissions generated by the building in use, but also those generated in the construction of the building and the embodied energy of the structure.

16. Advantages and Disadvantages of ZEB: Advantages: Isolation for building owners from future energy price increases I ncreased comfort due to more-uniform interior temperatures R educed requirement for energy austerity R educed total cost of ownership due to improved energy efficiency reduced total net monthly cost of living

17. Contd … I mproved reliability: P hotovoltaic systems have 25-year warranties - seldom fail during weather problems - the 1982 photovoltaic systems on the Walt Disney World EPCOT Energy Pavilion are still working fine today, after going through 3 recent hurricanes E xtra cost is minimized for new construction compared to an afterthought retrofit H igher resale value as potential owners demand more ZEBs than available supply

18. Disadvantages initial costs can be higher - effort required to understand, apply, and qualify for ZEB subsidies very few designers or builders have the necessary skills or experience to build ZEBs new photovoltaic solar cells equipment technology price has been falling at roughly 17% per year . It challenge to recover higher initial costs on resale of building

19. Contd … while the individual house may use an average of net zero energy over a year, it may demand energy at the time when peak demand for the grid occurs. In such a case, the capacity of the grid must still provide electricity to all loads. Therefore, a ZEB may not reduce the required power plant capacity . solar energy capture using the house envelope only works in locations unobstructed from the South. The solar energy capture cannot be optimized in South (for northern hemisphere, or North for southern Hemisphere) facing shade or wooded surroundings.

20. ZEB Definitions Summary table

21. Contd..

22. Zero energy building versus green building The goal of green building and sustainable architecture is to use resources more efficiently and reduce a building's negative impact on the environment Zero energy buildings may or may not be considered "green" in all areas, such as reducing waste, using recycled building materials, etc. However, zero energy, or net-zero buildings do tend to have a much lower ecological impact over the life of the building compared with other "green" buildings that require imported energy and/or fossil fuel to be habitable and meet the needs of occupants.

23. Some Examples of ZEB Largest ZEB in USA which belongs to Research and Support Facility under National Renewable Energy Laboratory (NREL)

24. Residential ZEBs The Charlotte Vermont House was able to achieve Net Zero Energy use by using the natural resources of the site—the sun, the earth, and the wind. Completed NREL/Habitat Zero Energy Home

25. Zero energy house at CES As the name implies, the energy generation in the building is equal to the energy consumption throughout the year. It is constructed in 30 ropanies land of Institute of Engineering at Pulchowk . It was funded by HMG/Nepal. The building has 3 and half floors which includes CES administration offices, classrooms, research cubicles, labs/ workshop and 4 comfortable guest rooms totaling 20,000 square feet. Main source of energy in the CES building is the 6.5 kW capacity of Solar PV system. 100 no. of Solar PV modules each of 65 Watt are kept as a roof on the main entrance of the building. The slope of the panel is 30? North-South. With the sunshine hours of 4.15 hour peak sun day, it generates electricity of 27 kWh in a day.

26. Contd.. The electricity generated is stored in battery banks kept at the basement of the building. 120 batteries of heavy duty nature, each of 2 Volt capacity 468 AH, are connected in series which produce 240 Volts. Such two battery banks are connected in parallel and each produces 240 Volt DC. An automatic software controlled inverter continuously monitors the whole process of the electricity generation from solar panel, storing in batteries and the connection to the grid as well. The inverter also supplies the excess power generated to the campus grid.

27. Features of ZEH at CES ZEH is managed with state of the art Building Energy Management System. It is well equipped with a sophisticated software controlled sensors. The system continuously monitors the occupancy of each places and it is programmed for managing the lights in those places sensing the motion of the occupant. The system also detects the Carbon monoxide level and humidity level in the designated areas, and maintains the database of the same.

28. The concept of the Earth air Tunneling for air conditioning spaces in winter as well as in summer has been materialized in the building. The conference room and a class room of the building are air conditioned with EAT. It takes in ambient air from a 70 m long tunnel made of hume pipe 4 m (0.5 m dia ) deep down from the Earth surface.

29. Conclusion Each of these leading-edge case study buildings demonstrates the progress toward achieving ZEB goals in real-world examples Only the Science House has achieved the site and source ZEB goal The other one- story buildings—Zion, BigHorn , and TTF—could achieve ZEB within their roof areas for all the definitions except cost ZEB. ZEB is not feasible for the two-story buildings unless their loads are further reduced.

30. Contd … We expect that the building will achieve a site, source, and emissions ZEB, but that a cost ZEB will be difficult to reach without further demand management controls. A cost ZEB is the most difficult ZEB goal to reach because typical commercial rate structures do not allow for net metering such that exported electricity can offset all other utility charges. To reach a cost ZEB goal, the credit received for exported electricity would have to offset energy, distribution, peak demand, taxes, and metering charges for both electricity and gas use.

31. Thank you!!!!

32. Questions for you Why only the Science House has achieved the site and source ZEB goal? what is Net off-site zero energy building? When was ZEB installed in Pulchowk Campus? What is the capacity of solar PV installed in CES? What is On grid PV and Off grid PV? Do y ou have any idea about AC Mini grids?

33. Answers because it is a small building with a relatively large PV system. A building may be considered a ZEB if 100% of the energy it purchases comes from renewable energy sources, even if the energy is generated off the site . 2002 6.5 KW The difference is that on-grid PV systems do not use a battery bank, and thus, their cost is anywhere from 30 to 40% less expensive than off-grid systems. AC Mini Grids significantly reduce the size of battery banks, and thus, the overall cost of large scale Solar PV.

34. Questions???