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Promise of green building
- 1. James Connelly LEED ap Fulbright Research Fellow Tsinghua University Dept. of Building Science The Promise of Green Building in China The growth of building energy consumption and the potential of green building rating systems. Shanghai Green Energy Research Center ★★★
- 2. Outline China Building Energy Current Situation Factors Behind Building Energy Growth Green Building Rating Systems LEED 3-Star Conclusion
- 3. Current Situation Source: Tsinghua University Building Energy Annual Report 2010
- 4. Current Situation Compared to Chinese urban buildings American building consume; 10 times more energy per person, almost 3 times more energy per unit of floor area. Chinese rural building consume even less.
- 5. Building Energy Growth As countries develop building energy usage intensity increases China Is at the same level as Japan in the 1960, US in the 1950’s. Source: Tsinghua University Lectures, Professor Jiang Yi
- 6. Why do developed countries buildings consume so much energy? Chinese building on average have: Less stringent building codes Less insulation, leakier windows and doors Less advanced heating and cooling systems Yet, they still only consume less than half of the energy of American buildings! Why? The answer lies in two interrelated factors: Lifestyle and Culture System Design and Operation
- 7. Culture and Lifestyle Chinese buildings have: Less appliances, particularly clothes dryers Less penetration of hot water Greater range of acceptable indoor temperature Example my office in Beijing, Jiuzhaigou in the Winter Utility bills are a greater proportion of income => Culture of energy and water savings 2 examples: water and lighting
- 8. System Design and Operation China: US: Part-time Part-Space Full-Time Full- Space Part-Time Lighting Full-Time Lighting Small Volumes Large Volumes Operable Windows Sealed Buildings Decentralized Systems Centralized Systems Individual Control Centralized Control Split Unit Air Conditioners Centralized HVAC VAV Point Source Heating Systems Source: Tsinghua University Lectures, Professor Jiang Yi, 2011
- 9. Case study: space heating in China Heating in North V South China 沈阳 银川 北京 苏州 武汉 上海 温州 调研城市 Source: Tsinghua University Lectures, Professor Jiang Yi, 2011
- 10. North V South China South: North: Individual units relatively District Heating relatively inefficient, yet… efficient, yet… Part-Time Part-Space Full-Time Full-Space Intermittent Operation 24 hour Operation Fee By Sq Meter Fee by usage Lower indoor temp (14- Higher indoor temp 16C) (20C) Heat Energy: 5-10 Kwh/m2 Heat Energy: 90 Kwh/m2 Much Less than developed Similar to developed Countries w/ similar climate Countries w/ similar (40-60 kwh/m2) climates Source: Comparative analysis of energy use in China Building Sector: current status, existing problems and solutions, Energy Power and Engineering China, Shengyuan Zhang, Xiu Yan, Yi Jiang, Qingpeng Wei, 2010
- 11. Split Unit AC saves energy Unit itself is relatively inefficient, but… Unit can controlled individually (decentralized) When is comfortable, or unoccupied, unit is shut off (intermittent operation) Occupants actively control system to minimize energy consumption
- 12. Centralized HVAC VAV systems waste energy through reheating Cold air is provided at low set temp to each room Fresh air must be provide to meet min req. (US 15cfm) If the room is too cold => reheated at the terminal Upenn Case Study: 50-70% of energy is used to Reheat Reheating not technically allowed under Chinese codes Source: Tsinghua University Lectures, Professor Xia Jianjun, 2011
- 13. Split Unit V Centralized AC AC energy for residential units in Beijing Average of AC energy during summer for each building: kWh/m2.a 20 18 kWh/m2.a 16 A，split unit 14 12 10 2006 8 2007 6 4 2 B：split unit 0 A B C D E D E V Centralized R V AC C：split unit Source: Tsinghua University Lectures, Professor Jiang Yi, 2011
- 14. Lifestyle and System Design are Interrelated System design effects occupants ability to actively reduce energy consumption. You can’t open the windows in a sealed office building. You can’t turn on the AC in only one room when you have a centralized system. You can’t save energy by turning up the thermostat when your HVAC VAV terminal just reheats the air. As countries develop => adopt developed country standard heating and cooling technology => lifestyle changes and energy usage intensity increases Slowing and preventing this transition is critical to reducing building energy consumption in China
- 15. China’s 2 Modes of Development Modern Western Standard concrete style office towers housing and office in central business blocks surrounding districts and in the suburbs
- 16. Profile of Energy Consumption Low Energy cluster around 30-40 Kw/m2 High Energy cluster around 120-150 Kw/m2 Source: Tsinghua University Lectures, Professor Jianjun Xia, 2011
- 17. Are Green Building Rating Systems (GBRS) the answer? 2011 China Green Building Action Plan proposed a 75 RMB subsidy per sq. meter to developers seeking to achieve 3-Star. Source: USGBC project Directory, MOHURD (does not included 3-Star data for November & December
- 18. Similarities: LEED and 3 Star Both checklist rating systems Break green building into categories: Land Saving, Energy Saving, Water Saving, Material Saving, Indoor Environment 3- Star has one additional category, Operation Pre-requisites (or Control items) in each category Different levels of achievement (1,2,3 star) Comparison to a theoretical “baseline” design
- 19. LEED uses a developed country baseline China “Large Public Building” Average: 36 Source: New Building Institute, Energy Performance of LEED® for New Construction Buildings, March 4, 2008, Tsinghua University Building Energy Annual Report 2010
- 20. LEED Uses Energy Models for Certification Current Energy Models are not an accurate predictor of building energy consumption. New Building Institute, Energy Performance of LEED® for New Construction Buildings, March 4, 2008
- 21. Is 3-Star Better? Chinese standards and codes Pre-certification, 1 year post occupancy evaluation, 3 Year follow up More pre-requisites, minimum achievement in each category Focus on on simpler and cheaper solutions, less on advanced technology
- 22. Scoring System (commercial) Standard by People’s Republic of China, Evaluation Standard for Green Buildings. 2006.
- 23. Different But Complementary Philosophies LEED is an industry run organization => greater focus on market transformation 3-Star is run by government and universities => greater focus on energy policy goals
- 24. Different Market Segments LEED: Class A Office, Luxury 3-star: Government, Public, Residential High-End Residential Raffles City Chengdu | LEED CS Vanke Gardens Shenzhen | ★★
- 25. Conclusions GBRS must consider a country’s state of development and energy baseline. Attention must be paid to the relationship between system design, lifestyle, and consumption. LEED and 3-star are complementary. Both rating system must increase transparency and collection of actual building data.
- 26. Xizhuang Integrated Building Shanghai ★★★ Thank You James Connelly seamus.con@gmail.com ChinaBuildsGreen.com EcoCityNotes.com
Hinweis der Redaktion
- Buildings are 25% China’s total Primary Energy Consumption. Compared to China US building consume: 10 times more energy per person, which is to be expected we have much bigger home, bigger, offices. But something that was surprising to me when I first came to China, and is continues to be surprising to American and European Architects and Engineers, is that perunit of floor area Chinese Urban buildings consumealmost 3 times lessenergy. Ruralbuilding consume even less.
- It is useful to look at the historical growth in building energy usage intensity to help understand why American Building’s consumer so much morethan Chinese. As countries develop their energy usage intensity increase in correlation with increases in GDP. China consumption level is now the same as Japan in the 1960’s and the USA in the 1950’s. Both Japan and the US from that low baseline subsequently made huge increases in building energy consumption. So keeping China’s building energy consumption low, or even more optimistically improving the energy efficiency of China’s buildings,is a tall order – they are already relatively efficient. To understand what this mean for green building in China now, we nest need to understand that factors that cause this jump in energy consumption.
- This is really a bit of a paradox for most Western architects and engineers coming to work in China. And some Chinese architects as well. On average Chinese building have less stringent building codes, less insulation, leakier windows and doors. And the heating and cooling system are generally less technologically advanced. Yet, somehow they still only consume half the energy of American buildings per unit of floor area. Why? The answer lies in two interrelated factors: differences and Lifestyle and Culture, and Building System Design and Operation. Now I’ll try and unpack these ideas.
- The difference culture and lifestyle between the US and China has a significant impact on the occupants energy consumption. On average China building have less appliances, less flat screens, and most importantly, only rarely have clothing dryers, which is the biggest consumer of energy in a residence. They also have less penetration of hot water. Another critical factor is that Chinese buildings a larger range of acceptable indoor temperature. I’m sure everyone in Beijing has experienced how hot and stuffy it can get indoors in the summertime in Beijing. I didn’t really understand how perhaps spoiled I was until this summer in my office in Beijing. We have, about 30 computers running full blast and poor air circulation, but no AC, so it can get incredible hot. People just learn to adjust by wearing more or less clothing as the seasons change. I had the opposite experience when I was in Northern Sichuan last week with no indoor heating, It was so cold I had to wear all my clothes and my hat just to feel warm enough to go to bed. Finally, because utility bills are a bigger share of disposable income, therefore China has a developed a culture of every and water saving to save money. Example: When we turn on the hot water in our apartment for about 1 minute cold water comes out, so I just went I brushed my teach or whatever until the hot water came on. Then one day my roommate asked me isn’t your major green building, why are you wasting so much water? He showed me how he takes a big bowl and puts into under the shower while its cold to save the water, then he uses it to wash clothes, or flush the toilet. This is something I just never would have considered growing up in the us where water and electricity are so cheap.
- However, while cultural and lifestyle factors are important, System Design and Operation is equally if not more important. In China Building are generally desisgned to have small discrete volumes, operable windows, part-time individually controlled lighting, and individual control of heating and cooling Systems. Professor Jiang Yi at Tsinghua refers to this as part-time part-space operation vs. full-time full-space. Part-time part-space is characterized by individual room air conditioners that you can switch off by yourself, in contrast to American building that are generally design with a completely sealed structure where you can’t open the building, and lighting that light up some portion of the building 24hours a day. Furthermore, because the building is sealed from the outside, A centralized high-tech air handing system is required to heat and cool the entire building. To illustrate how this difference in full-time full-space operation v part-time part-space operations results in energy savings, I’m going to use 2 examples from China: Heating in Northern V Southern China, and AC systems Design.
- In a top-down governing fashion China has been divided into two regions for heating. Above this red line just North of Shanghai, heating is provided 24/7 in a full-time full-space manner, through district heating. Since we are all in Beijing we are familiar with this. The heat is turned on on a specific day, and from that day on our apartment have hot water heating all throughout the Winter. However below that line heating is not provided. To heat your home you have to have your own individual heating unit. So comparing the two is a clear case study of the different energy consumption habits that occur when employing either part-time part-space or full-time full-space heating modes.
- In SouthernChina, below the heating line, buildings have individual heating units. They are, in fact, relatively inefficient when compared to radiant heating deployed by a district heating plant. These are the large smokestacks you see in Beijing neighborhoods that burn coal to provide hot water for your apartment for heating. In Southern China the heat is only turned on as needed and residents pay more money depending on how much energy they use, while in Beijing you just pay a fee based upon the floor area of your apartment. Therefore, residents in Southern China, because they have control over their systems, and pay for them, will only operated them just as much as the need. To conserve energy and save money they will keep the temperature much lower (around 14°-16°C 57°-61° F). Occupant controlled heating units and small volumes makes intermittent operation feasible and residents have an incentive to save since they pay for every incremental increase in heating energy consumption. Responding to the price incentives Southern residents adjust their lifestyle wearing more clothing in the Winter vs. Northern residents that take 24 hour heating for granted. In fact southern residents only consume around 5-10 KWh/m2 which is much less than developed countries with comparable climates, while Northern residents consume 90kwh/m2, which is on par with developed countries with warm climates. In fact, A Tsinghua University report shows “intermittent” operation combined with a lower set point can reduce energy consumption by seven times, without changing anything about the climate, the system efficiency, or the thermal performance of a building.
- So not that I’ve talked about how part-time part-space operation save heating energy, lets look at the air conditioners we all have in our apartment or offices. I think, for any Chinese audience member that we have here that have never been to the States, you might be surprised to see that you almost never see these type of split-unit AC systems in the US. We almost always have centralized AC. But these units, are great the help save energy. Why?Not because they are necessarily very efficient, in fact the opposite, they are relatively inefficient. But they can be controlled individually and intermittently. When the room gets warm the unit is simply shut off. Therefore, the occupants actively manage and control the units in order to conserve energy.
- In contrast most US buildings use very large chillers and HVAC systems. Not only is it difficult to control these system on a individual room by room basis, the way that most standard office building are set up, with an HVACVAV system, they are especially wasteful. The systems work by provided cold air to the room at a specific set point, the lowest temperature necessary for the room that has the highest cooling demand. Because all their air is provided by this system it is also required to provide all the fresh air to each room at a set rate of 15cfm per sq ft. Therefore if an individual room gets too cold, and the thermostat is triggered, a VAV system will heat the air up again at the terminal. This means even if you want to turn the heat down in the summer, it will be even more wasteful, because the system will cool the air below the temperature needed and then heat it up again. You waste heat twice. In a THUBERC study, 50-70% of the system energy was wasted or counteracted by reheating. In fact, in China, reheating is illegal according to current building codes, although certain projects still deploy it anyway, because is is very different to balance an HVAC system in a modern glass skyscraper without reheating.
- Centralized HVAC are not only popular in America, it is becoming popular in China. As you can see from this case study out of in Beijing. Building ABCD, which have split unit systems, consume almost ten time less energy than the building with centralized AC. Centralized systems so far are only in the most high end luxury (serviced apartments) but they are growing in popularity.
- Therefore, you can see that lifestyle and system design are interrelated. The, system design effects the occupants ability to actively reduce energy consumption. For example; you can’t open the windows to save energy in a sealed office building, tou can’t turn on the AC in only one room when you have a centralized system, and you definitely cant save energy in the Summer by turning up the thermostat when you have HVAC VAV, because the terminal just reheats the air, wasting more energy. As countries develop and GDP grows, building design begins to incorporated developed country technology, particularly in heating and cooling, this allow you to have glass completely sealed buildings, in part a consequence, and at the same time, lifestyle changes. We get used to 24 hour heating and cooling. We forget to run the heat down and wear a jacket. This explains the huge increase developing countries make as the transition to middle income and high income countries. And it is preventing this transition that is the most critical factor in reducing building energy consumption.
- And this transition is already underway in China. You can see it visually in every major city; you have buildings like to the picture at the left with tall modern, glass enclosed Skyscrapers, and then to the right you have your standard concrete housing and office blocks, designed in standard Chinese fashion, with operable windows and split unit air conditioners. I love this picture because I was up in this very tower a couple months ago, and it was so striking seeing the difference between the monopoly hotel looking building on the left and the massive and really impressive skyscrapers on the bund and in Pudong.
- You can see the energy transition in the profiles of Chinese building energy consumption right now. In most cities with some modern building you will see a cluster of building around the 30-40 kwh standard Chinese construction range, and then a much greater higher energy cluster around the 120-150 kw/m2 range.
- So are are Green Building Rating systems that answer to preventing this energy transitions. Two rating systems in China, the 3-star system run by the Ministry of Housing and Urban Affairs (MOHURD), and the Leadership in Energy and Environmental Design (LEED) program, originally designed by the US Green Building Council are helping to ensure the promise of green building is more than just hype. By provided an objective and trusted seal of approval these rating system help create accountability; transforming the building marketplace so that environmental performance metrics become part of the economic equation. And these rating systems are growing incredibly fast. This leaves chart leaves out any additional project that were 3-Star registered in Novemeber and December, but even so the growth rate of 3 star is higher than LEED. It grew 191% in 2011, while 3Star only grew 29%. Additionally, according to Professor Borong Lin at Tsinghua University, China's upcoming Green Building Action Plan will most likely include a 75 Yuan per sq meter subsidy for developers who achieve a 3-Star certification of any level. 75 Yuan represents about 30% of the extra cost that it takes to design and build a 3-Star certified building over standard construction,so I expected 3-star registration to grow even faster.
- The ministry of Housing and Urban Affairs three star system was originally based on LEED and shares a similar structure. They are both Checklist rating systems, which give the developer the flexible to choses from a number of different Green Bulding credits. For examples, improving energy efficiency by 5%, or using renewable materials. 3-star then breaks green building into 4 categories roughly equivalent to the LEED categories: Land-Saving, Energy Saving, Water Saving, and Indoor Environment. 3-star has one additional category not in LEED which is called, Operation, which is concerned with commissioning and operational management of the building systems. Within these categories there are “control items” as 3-star refers to prerequisites, and then additional level of acheivement that will result in a higher score. So in three star you can score, 1, 2, or 3 stars, 3 being the best, and in LEED you can score certified, silver, gold, and platinum. These rating systems work by giving you credits or points, based upon how well your building compares to a theoretical baseline building. That means to show that your building is energy efficient and get energy credits you have to show that it is more efficient that a baseline building using standard codes and certifications. For example to achieve additional energy credits you have to shoe with an energy model that your building is 10% more efficient that a baseline project. And it is the difference in the baseline that really differentiates these systems.
- LEED, since it was designed in the US and Used in the US, not surprisingly uses a Developed Country baseline. Full-time full-space, a centralized AC system, in reference to international standard and codes. A report in 2008 measuring the energy performance of LEED buildings showed that they were 24% more efficient than all commercial building and 33% more efficient than standard US office buildings. However, there is a lot of controversy about this report because it left out a lot really high energy consuming building: data centers. But regardless of that, China’s large building consumption level is lower than an average or even a great LEED building. That means that a good LEED project is unlikely to be able to prevent China from making that energy transition that we talked about earlier in its current form.
- Furthermore, LEED only uses energy modeling to determine its rating system, LEED does not require follow up to ensure that building are actually achieving the energy performance criteria they signed up for. While in aggregate, energy models models are an accurate predictor of energy performance, on a case by case basis, some LEED buildings actually consume much more energy that modeled energy baseline.
- In contrast 3-Star uses Chinese standard and codes to for the the baseline comparisons. Furthermore, in 3-star you can achieve a green building design label before the project is built, but it cannot actually be certified until after a one year post occupancy evaluation, to make sure the building actually achieve the criteria it said it would. Then the building is followed up on every three years. 3-Star also has more pre-requisites and you need to achieve at minimum 1-star in each category. However, the criteria for many 3-Star credits are a bit more, subjective, compared to LEED which has a really long history and record of credit disputes and the definitions have really been honed down over time. 3-Star relies on a panel of experts to asses whether a project is truly green and achieves a credit or not. 3-Star also has more of a focus on simpler solutions, like increased insulations and solar shading, opposed to technological ones like geothermal heat pumps and advanced HVAC systems.
- In LEED all your credits are just totaled for your final score, Therefore you can credit shop, and choose only the easiest credits to achieve. In fact, in previous versions of LEED, it was possible to get a certified building without any energy credits! The most important credits!The most notorious example of this in LEED was adding bicycle racks and electric vehicle chargers to get a credit whether or not they actually would be useful. This has however been remedied in LEED 2009 which weights credits based upon their environmental impact. 3-Star, on the other hand, requires that you have balanced performance across categories,meaning to achieve one star you have to achieve all the one star criteria for each category.
- Many Western Architects I meet criticize 3-star for being too vague and lacking the brand name and trusted system of LEED, while many of the Chinese academics I work with are rightfully very critical of LEED, because,in many ways it is not very well matched to the Chinese Context. However, my opinion is that they both are necessary, and I’ll explain why. LEED, is an industry run organization set up by real estate developers, green building material suppliers, and architects and engineers in order to generate a marketplace for green buildings. And on this goal it has been incredible successful in promoting the idea of green building across the world. Without LEED there would be now 3-star. On the other hand, 3-Star which is a Government run and University run program, is more pragmatic and is more focused on achieving the specific policy goals of reducing energy consumption.
- I think this two project illustrate the different between the two market segments the rating systems survive the building on the write just topped out in Chengdu. I visited the site last week and it’s a great project. And very typical of the type of projects where LEED could make a big difference. It is already designed to a western standard so a western rating system makes sense. On the other hand this small development by Vanke, that still has operable windows and individual split unit air conditioners is a perfect match for 3-star, helping to keep these projects from transitioning to western level of energy consumption.
- In Conclusion I have four main points. First, Green Building rating systems, and really all effort to reduce building energy consumption must take into account a country’s state of development and its energy baseline. Second, attention must be paid to the relationship between the system design, lifestyle, and consumption. It is not just the case that American’s operate their building in a wasteful way, it is that our system’s are designed so that it is very difficult to operate them in a part-space part-time basis. And if China transitions to that same mode of system design, I’m afraid China will develop the same wasteful lifestyle and culture. Furthermore, due to the two modes of development and the energy transition in China, I believe both rating systems are both necessary and complementary. LEED helped blaze the market, and is appropriate for high end project already designed to western standards, while 3-star is important to provide leadership for the rest of the market especially public building and standard Chinese construction. And as it builds a name for itself international developers will begin asking for it as well. Finally both rating systems need to improve the transparency of data so we can know whether or not they are really saving energy. In this way we can continually upgrade the rating systems if we discover flaws. If we improve transparency of data and continually revise the rating systemsthey will live up to their promise to transform the building marketplace in China and place it on a more sustainable path.