Energy Intensive Q&A

  • Posted in Default
  • By admin
  • Date September 17th, 2013 16:07
  • Follow
  • Our 'Energy Intensive' panel discussion drew a large audience and generated great discussion. For those who missed the event or for those who want to review the discussion, the dialogue (and loads of expertise) can be found below. If you have further questions, or want to add to the discussion please contact us

    Answers to the Q&A are separated into 4 sections, according to the panelists:


    2. EDWIN LEE





    JOSEPH VAN DER ELST (Senior Project Engineer, energydesign Shanghai):

    If we compare two products; each identical, but produced in different countries do they each have the same embodied energy?  Why do embodied energy calculations depend on the country where the product is manufactured? 

    JVDE: Even if manufactured through identical process, two products’ embodied energy will vary from one country to the next, because of what is out of the industrial process but is used by the industrial process: energy, generated with different techniques from one country to another; but also, roads, trains, harbors, schools, hospitals.... And different energy generation techniques have very different energy efficiency. Moreover, their embodied carbon can vary dramatically, depending on the country of production.

    How is transportation energy in embodied energy calculations?

    JVDE: It depends on which transportation you are talking about, and how were the system boundaries defined.

    Let’s take the example of an automobile:

    • transportation of its users will be part of the automobile’s operation energy.
    • transportation of the engine from the engine factory to the final assembly line will be part of the automobile’s embodied energy.
    • depending on the system boundaries’ definition, one could also include a share of transportation of the sales representatives of the automobile’s brand, and of transportation of concept cars from shows to shows, in the automobile’s embodied energy.

    Can you explain the boundaries of the LCA? What variables are included and which are most critical?

    JVDE: LCA can go look into more emissions (SO2, PO4, C2H4, R11, …) and more resources (primary energy, water, land use, social discrepancies…), but it follows the same principles.

    Definition of boundaries is the setting of the case, so it all depends on what is one’s case.

    Generally, it is a balance between what one would like to take into account (every consequences) and what one can take into account in terms of access to -reliable- information, and without becoming too complex. To be able to perform this balance, one should first start by giving its priorities a clear hierarchy.

    In my opinion, the hierarchy in priorities should be the following: climate change mitigation, anticipation of energy shortage, in order to adapt to climate change.

    What industry changes would result in a better accountability of carbon?

    JVDE: The economic system is very good at optimizing. The only problem is that it does not take stocks (of resources, of admissible carbon or other emissions…) into account (take a close look at what is GDP, and you will see). It worked well in a world considered infinite. It is a big problem now that humans are much more numerous, making much more stuff: because, in the end, the world is finite.

    Or we could just give this system a new goal: put a price on carbon or raise energy prices artificially (x4 or x8, no less!).

    Calculating the carbon of a single material seems straightforward, but how is construction carbon typically measured? What assumptions can design teams make about systems, materials and construction methods to approximate the impact of construction? How far should these assumptions be used to guide design decisions?

    JVDE: “How much does your building weight, Mr. FOSTER?” Richard Buckminster Fuller

    “????” Norman Foster

    Calculating embodied carbon of a single material is not as straightforward as it seems. Try to follow a pair of jeans and you will find out.

    So for a building it is just more complex. What we do is rely on database that compiles generic materials Life Cycle Inventories (LCI). And then we pick all relevant materials’ LCIs to compile the studied building out of them. It is complex and time consuming.

    To guide design decisions, it is important to adopt a variant comparison approach and keep track of decisive parameters.  We need to consider the overall LCA impact, but also other parameters such as a product’s weight, its performance, etc.

    To evaluate LCA impact, one should dig in the manufacturing process; the more energy-intensive the processing or fabrication methods needed to produce the material, (such as high temperature requirements, strong magnetic fields needed, or very high speed requirements) the higher the LCA impact, specifically when it comes to carbon.

    But before ruling out any material, we need to look at the consequences of each decision.  The type of insulation specified for example, hugely impacts a structure’s weight, however what is the embodied carbon trade-off for using that insulation?  We must keep in mind that every decision is a trade-off between conflicting parameters.

    Another way is to focus on the big numbers: reduce the overall mass of concrete of the building.  This requires that everything in the structure be lighter.

    The University of Bath has developed a database of embodied carbon values for general materials (ICE). In China, SRIBS is working on defining similar values but their database isn’t complete. Until a China-specific database complete, can ICE data be manipulated or converted to be relevant in China? What are the assumptions or potential errors that designers should be aware of when using non-China data? 

    JVDE: If you are looking at carbon and energy only, the China-specific data is available in the Bilan Carbone® tool since 2004.

    If you are looking at parameters, within your LCA, the CLCD can be downloaded using the eBalance software. CTC and SRIBS are building on the CLCD to develop a database this is more focused on construction materials.

    About assumptions comparing UK with China:

    For highly secondary manufactures goods (from factories), embodied energy should give relatively better results in China, as industrial revolution came later, benefitting from better technology, and higher investments, and as human labor is maintained wherever it can be.

    For highly tertiary services (from offices), on the other hand, embodied energy might be higher in China, as building standards are rather low in terms of energy efficiency.

    For embodied carbon, results would turn much worse in China because of its energy mix relying mostly on Coal.

    To give an order of magnitude: I ride an e-bike around Shanghai. Educated in France, I had in mind that it would have a positive impact on my carbon balance, in addition to being the most fun transportation. It turns out it is not true, as for the same weight and speed: In France: Global Warming Potential (GWP) emissions are twice as bad for a petrol-powered engine bike than for an electrical bike.  As the French energy mix relies mostly on Nuclear.

    In China, it’s the other way round: GWP emissions are twice as bad for an electrical bike than for a petrol-powered engine bike. As the Chinese energy mix relies mostly on Coal.

    EDWIN LEE (PE, Fellow ASHRAE, LEED AP, FCIBSE, Managing Principal Glumac Asia)


    What do you find are client’s biggest concerns when it comes to HVAC systems? Is it overall performance, IAQ, ease of maintenance and operations, or simply the up-front costs?  Of these concerns, are they all “real issues” or are some of them misconceptions?

    EL: Our clients in China expect us to design a high performance system compatible with the ones that we have been designing in the US! But the biggest concern our clients have over these systems: can we do the system here in China! Can we obtain the equipment or material for this high performance system in China! 

    Then again, the biggest resistance is still coming from the local engineers here in China, the Design Institutes who has the design authority over us, aren't willing to accept these high performance system which they haven't had the experience with. Most of the concerns are misconception due to the push back by the local design institutes.

    Do international Green Building Certification systems and standards account for differences in local VAV and VRV systems? What can project teams do to account for these disparities when certifying a local building?

    EL: Yes, some of the approved energy simulation software system will be able to differentiate these two systems from the energy baseline. Proper sizing or may I say right sizing and good engineering of these systems will help a lot.

    We hear a lot about high-tech energy-efficient buildings. Is this approach suitable for China? Or should we focus on a foolproof passive approach such as natural ventilation or free cooling? Can we even take advantage of these approaches in Shanghai? 

    EL: A highly energy efficient system should be designed (for users friendly) to be easily operated by the maintenance crews in China. The education and caliber of the maintenance teams are usually not as good as the design team in China. System needs to be designed to suit the caliber of these folks too.

    Based on the outdoor temperature in Shanghai, free cooling on air system can be used for about 15 to 20 % of the time throughout the year for a normal office building.

    What systems would you suggest could lead to improved IAQ and energy savings? Are there other synergies that help core systems achieve better performance? 

    EL: Under floor air supply system or displacement ventilation will get us improved IAQ and energy savings. Yes, one of the best synergies is to have a good building Management system with all the appropriate sub-metering devices to assist in monitoring the system and trending the data to assist the fine-tuning and operation of the system in achieving its most optimized point of operation.

    PHILIP RAFAEL (Associate Director, studio illumine)

    In your presentation, you mentioned the “rebound effect”.  What is this and can you propose a solution for it; how can designers best counteract the effect?

    PL: The rebound effect is a wider issue that does not only affect lighting. It is an observed market tendency that occurs when a higher efficiency product is introduced into the market at a lower or equivalent cost. The increase of efficiency tends to increase the product’s availability that potentially results in the increase of use. The increase of use counter acts the initial energy gains.

    Designers can counter act this tendency through critical thinking. Designers need to distant themselves from popular but unjustified trends that tell us that more is better. A designer should question the lighting targets and search for saving possibilities; question user habits and control strategies and see when possible to turn off or dim lights; question the supply chain and search for more sustainable sources; etc.

    What’s “variable load shedding”? Can you give us an example of how to generally apply this technique to lighting design?

    PL: Variable Load shedding is decreasing the energy load of a building by a small percentage; this is achieved by a variety of strategies. Lighting can impact this by dimming slightly all the lighting of the building. The dimming is performed so slowly that it is not noticed by the users and will result in additional energy savings.

    In terms of sustainable design, why isn’t energy efficient lighting enough?

    PL: Energy efficiency is only one aspect of a sustainable design. To be sustainable we must consider human/social, environmental and economic aspects.

    Sustainable lighting designers should maximize the energy efficiency of their project but they should also look at possibilities of reducing the lighting levels such as circulation and interim areas or breakouts. Designers can also source their products sustainably, ensure that the specification minimizes the use of toxic agents such as mercury, etc.

    What is necessary is a sustainability-orientated mindset, one that looks beyond energy efficiency.

    What lighting design strategies optimize building energy performance?

    PL: The best lighting design strategies can be achieved through intelligent controls. Daylight linking would be an essential strategy. In addition to this there is time scheduling, occupancy and absence control, maintained illuminance, etc. 

    A very important strategy that is rarely used (almost never!) is setting maximums for lighting levels. It is very common to say a space requires at least 300 lux but how many times have you heard that a space requires under 350lux. Lighting level targets should be achieved within a +/-10% range. Clients should deem lighting levels that are under or over beyond 10% as unacceptable.

    You referenced glazing in your presentation and its high-embodied carbon “cost”.  Are you suggesting that because of the embodied carbon of glass, daylight design is not sustainable?

    PL: I must continue to emphasize that sustainability refers to responding to human/social, environmental and economic needs. From an environmental perspective, glazing is indeed negative because of its low insulation and solar values (R and G value) but from a human perspective, access to daylight is an essential part of our lives. Daylight has such a positive biological (circadian rhythm) and emotional influence on us that it would be unthinkable to build a black box building unless specially required.

    From a carbon perspective, it is an interesting exercise to try and understand what is the tipping point where carbon savings achieved through energy savings are capable of counter balancing the carbon footprint of the glazing. 

    My point is that just as it is not sustainable to build a glass box, it is equally not sustainable to build a black box. Introducing the embodied carbon into the sustainability equation does make this balance more complex but it is necessary that designers are capable of taking on these difficult challenges.


    ROLAND GUNNESCH (Architect, Researcher)

    1. From your own experience, what are some symbiotic systems that work well together? Within the area of your own expertise, do you have any general rules of how to integrate design for best results?  Can you think of any systems that complement one another, or ones that don’t?

    When understanding buildings as organisms we're overwhelmed by the ability of symbiosis given in biological systems.
    Buildings and their components don't communicate to each other, but the people that design them do. There is of course the trend to implant a building brain such as advanced controls and building automation systems, which again are designed by people.

    Therefore, an interdisciplinary design approach yields a great potential to make the building components and systems work in symbiosis. To increase energy efficiency of buildings e.g. daylight and artificial lighting, passive and active heating/cooling or mechanical and natural ventilation can form symbiosis.

    A general rule to achieve buildings with low environmental impact:
    1) lower the energy demand by appropriate occupant behaviour and adaptive thermal comfort
    2) reduce the demand further by high performance building envelopes and make use of renewable
         energy sources, sun and wind, by means of passive design strategies
    3) for the remaining energy demand integrate efficient building services

    2. Optimizing embodied energy is now a design focus in Europe for many reasons; the building stock is more efficient and relevant data exists and can be analyzed. Where does China stand in comparison?  Is it reasonable for designers in China to focus so much effort on calculating the embodied energy of buildings?

    A difficult question.
    First we should distinguish between the building stock as a whole and new constructed buildings following the code.

    According to Yang and Kohler (2008) the proportion of Embodied Energy (EE) to Operating Energy (OE) is much higher in China's building stock than in European countries, measured based on annual material production and average transformation efficiencies in the building industry.
    This is attributed to the higher rate of construction, lower energy efficiency of the production of building materials and the significantly shorter lifespan of buildings. Song (2005) estimated the lifetime of the Chinese urban buildings at only 30-40 years and less than 15 years for rural houses.

    Another possibly underestimated factor is the vertical density of mega-cities such as Shanghai.
    The CTBUH (2009) estimates the initial Embodied Energy per m2GFA of a 50 storey high-rise building as twofold in comparison to a low-rise (< 10 storeys). Increased EE of tall buildings is mainly due to the larger structural members.

    Architects that are working on new buildings question the priorities between operating energy and embodied energy. Maybe a rough estimate helps:

    For example a 45 storey commercial office building has an estimated Embodied Energy of 16 GJ/m2 (CBTU 2009) and its average energy consumption, when located in Shanghai, is estimated at 1.6 GJ/m2a (Weiding 2008). After 10 years, the buildings operating energy and embodied energy are in balance.
    Over a lifespan of 30 years the embodied energy accounts for roughly 25%. Such weight of EE makes it worth to spend some effort on its reduction potentials. Furthermore, as operating energy is gradually driven down by more efficient buildings the embodied energy becomes more significant.
    However as a general conclusion, with regard to commercial buildings in China, it seems reasonable to argue that reducing the operating energy remains a priority for now.

    A simple estimate can be done for different building types and locations to grasp an idea of the proportions of EE and OE over the building lifespan. So please keep an eye open for updated sources & statistics on Embodied Energy and Operating Energy of buildings in China and post them in the forum.

    3. You emphasized the importance of the building envelope as a key opportunity for carbon emission reductions. What is the optimal building envelope and what do architects need to consider in order to design such optimized envelopes?

    According to McKinsey (2009) in the time period up to 2030 a massive rise in energy consumption in offices is expected, with cooling energy as the major contributor. Within the Chinese building sector, the biggest opportunities for abatement of carbon emissions are efficient building envelopes for commercial buildings.

    A high-performing building envelope is responsive to the external environment and to the activity pattern of the building occupants. Therefore the building envelope acts as a filter between outdoor conditions and indoor comfort. For office buildings in the local climate a major challenge is to reduce solar heat gains while increasing daylight availability. The resulting cooling/heating loads and artificial lighting loads largely determine the energy for building operation.
    Further, reducing heat gains induced by solar radiation and artificial lighting has direct impact on the heat balance and can significantly lower the peak loads on HVAC systems, thus allowing a downsizing of equipment and their Embodied Energy.

    A potential design strategy is to develop facades that are adapted to orientation, each orientation with a specific set of glazing parameters adjusted to solar radiation intensity and the ratio of direct/diffuse radiation. Increased daylight levels are only useful if they are distributed so the objective for deep plan offices is to distribute light to the rear and reduce excessive illuminance in the perimeter zone. Further it is advised to adopt 'dynamic daylight metrics' which reflect the building orientation and the variability of sky illuminance.

    A good approach to optimize the performance of the building envelope is to conduct a sensitivity analysis of the major design parameters and simulate different design option in comparison to a baseline scenario. The building geometry and parameters of the transparent envelope (U-value, Solar Heat Gain Coefficient and Visible Light Transmittance) all play together and require tuning.

    4. You’ve specifically looked into the glazing industry in your research, but what data is lacking for materials in general?  What data is most needed now, so that architects can optimize the embodied carbon of buildings?

    Some data for EE of materials is now available from different sources, but it lacks comparability. The calculation methodologies and system boundaries are most disputed in the numerous research papers. Narrowing the boundaries does lead to underestimate the real impact, whereas extending the system boundaries does include more uncertainties.
    Ideally we would obtain the calculated Embodied Energy of materials based on clearly defined industry standards for the entire manufacturing process. A more realistic approach are the empirical averages and ranges of data entries from various industry sources, as exemplary given in the ICE spreadsheet from the University of Bath. (see Hammond and Jones 2011)
    What architects & engineers can do and have practised already without thinking about the CO2 numbers are efficient building structures, material-efficient construction methods and detailing with regard to durability and maintenance.
    Given any EE / EC numbers, architects still design intuitively. They need to weigh the Embodied Energy of alternative materials & components relative to each other and have those approximate values ready in the back of their minds when making design decisions.

    When specifying the glazing unit for higher performance, in most circumstances the selection that reduces operating energy also reduces total lifecycle energy. However not every option that is technically achievable is financially bearable.
    For residential applications in moderate climates upgrading to IGU's with Argon filling and low-E coating has a relative short payback period and generally yields high energy savings. When specifying a U-value below 1.0 W/m2K usually a third glass layer or higher insulating gases such as Krypton is required which has an additional embodied energy of 60 times compared to an Argon infill (Menzies and Wherrett 2005).
    A recent lifecycle analysis with extended system boundaries, indicates that the Embodied Energy for a building with PassivHaus standard can exceed 50% of total life-cycle energy over 80 years (Crawford and Stephan 2013).  

    For 'internal load dominant' commercial buildings in hot summer / cold winter regions such as Shanghai an over-insulation is inappropriate. Here IGU’s with a high Light to Solar Gain (LSG) ratio are desired with spectrally selective properties. Less research on Embodied Energy is available for glazing units targeted on those performance criteria.

    When it comes to the frames; for instance an aluminium frame has roughly 6 times more EE than a timber frame, whereas an alu-clad timber frame in comparison only about 1.5 times, yet equally UV-resistant and durable against weathering (Muneer et al. 2002). In some applications like high rise buildings, an aluminium frame is specified for its lightweight and strength, so one could examine alternative alloys or elements that use a high percentage of recycled aluminium.

    Think about how to best use material properties considering their 'relative' embodied footprint as part of the design routine. If not for research purpose, there is little use to do a detailed lifecycle analysis once the building design and material specs are finalized.
    To make EE data accessible to architects working in the design phases, it would be desirable to have a catalogue of building materials and generic building components with physical properties and Embodied Energy values & ranges on a relative scale (from low to high). Ideally in a Cradle to Gate boundary for the Chinese building industries.

    Theoretically, we need to drive a building design optimization with approximate EE data thus far to outweigh the uncertainties in the data that we use, so we would be better off than getting stuck with the argument there is not sufficient reliable data to work on it.

    5. On a more individual level, not everyone is in the architecture, manufacturing or building industry.  Yet, more and more people are becoming aware of embodied energy and embodied carbon.  What advice would you give to someone who is interested in reducing his or her own personal carbon footprint?

    Reducing one’s own carbon footprint can be simple, but it takes some discipline to really do it.

    Concerning the lifestyle; it is advised to use public transport for commuting to work, to ride a bicycle to the local grocery and to consume less meat. If possible, buy durable products and repair them rather than constantly chasing the latest trend that soon ends on landfills.

    Globally and in particular in fast developing countries such as China the energy consumption for household appliances is on rise, so control them by paying attention to energy labels and make sure you cut down the 'vampire loads' in your home (energy consumed in standby mode).


    Crawford, R.H. and Stephan, A. (2013). The significance of Embodied Energy in Certified Passive Houses.
    World Academy of Science, Engineering and Technology 78 2013 [Online].
    Available at:

    CTBUH, Council on Tall Buildings and Urban Habitat (2009). In Numbers: Tall Buildings and Embodied Energy.
    CTBUH Journal 2009, Issue 3 [Online].
    Available at: tabid/1211/language/en-GB/Default.aspx

    Hammond, G. and Jones, C. (2011). Inventory of Carbon & Energy (ICE) Version 2.0. Sustainable Energy Research Team (SERT), Department of Mechanical Engineering, University of Bath, UK [Online].
    Available at:

    McKinsey & Company (2009). China’s green revolution. Prioritizing technologies to achieve energy and environmental sustainability.

    Menzies, G.F. and Wherrett, J.R. (2005) Multiglazed windows; potential for savings in energy, emissions and cost.
    Building Serv. Eng. Res. Technol. 26,3 (2005) pp. 249-258 [Online].
    Available at:

    Muneer, T. et al. (2002). Life cycle of window materials - a comparative assessment [Online].
    Available at:

    Song, Ch.H. (2005). Whole life and highgrade quality - stick to the idea of giving first consideration for the people and implement housing performance certification. Housing Science, 290 (8), 3-7.

    Weiding, L. (2008). Tongji University. Energy efficient retrofit in existing large-scale commercial buildings. Proceedings of the Conference by Marcus Evans titled as 'Energy Revolution in Commercial Buildings'. Shanghai, 17-18 July, 2008.

    Yang, W. and Kohler, N. (2008). Simulation of the evolution of the Chinese building and infrastructure stock. Building Research & Information 36 (1), 1-19 [Online].
    Available at:


    On a more individual level, not everyone is in the architecture, manufacturing or building industry.  Yet, more and more people are becoming aware of embodied energy and embodied carbon.  What advice would you give to someone who is interested in reducing his or her own personal carbon footprint?

    JVDE: Ask yourself when and if you really want what you consume. A beef steak a day? An airplane trip, every holiday? If we were applying the carbon factor 4 (defined in the Kyoto protocol, to keep climate change within a reasonable range), equally for all inhabitants of the world, a return ticket Paris-NYC would reach one’s annual quota.

    EL: Use what you needed only and consume what you needed only.

    PR: Become conscious consumers.

    It is not expected that anyone be master of all knowledge, however if we are conscious that our actions and consumer choices have a carbon footprint consequence, we can then consume in a more eco friendly way with more sustainable alternatives or maybe even question whether it is really necessary to consume in the 1st place.

    From your own experience, what are some symbiotic systems that work well together? Within the area of your own expertise, do you have any general rules of how to integrate design for best results?  Can you think of any systems that complement one another, or ones that don’t?

    JVDE: Plants and water treatment. Agricultural activity and methanization (if out of waste, and not dedicated farming)...

    Contract project briefing: preliminary discussions including the end user, the owner, the architect and the energy/sustainability designer.

    Low-temperature-heating-/higher-temperature-chilling-loops reduce primary energy demand and ease integration of renewable energies in the energy concept (Ground source heat, Solar thermal,…).

    PR: I think it is obvious that lighting design is a symbiosis between lighting and electrical engineering.

    Possibly less obvious is the symbiosis with urban design: lighting can influence urban habits, space planning and building orientations. A lighting designer can apply sustainable practices that can lower the carbon footprint of a city.

    Daylight Design on the other hand is a compromise rather than a symbiosis as maximizing daylight may potentially increase the thermal load of a building through solar gains. A close cooperation between disciplines is necessary to achieve the optimal solution.

    For each of your respective trades, can you list a few resources or websites that are available for those seeking more information?

    JVDE: To start with the basic knowledge, and even a little further:

    To find example of actions at society’s level:

    To find a great attempt of exhaustiveness of actions at the building level: DGNB was the first building rating system to introduce Life Cycle Assessment.

    For tools to perform a carbon balance, with right approximations, and for China as well:

    For a carbon balance of your activities, as an individual (in French, but you should make it with chrome):

    EL: ASHRAE.ORG where contains a lot of design information.

    CIBSE.ORG where contains a lot of design information

    GLUMAC.ORG where contains a lot of sustainable design ideas.



server error: