Eco August 2010 Cover Story

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Botanical air filtration article written by Dr. Ronald Wood, published in "Ecolibrium" journal of the Australian Institute of Refrigeration, Air Conditioning and Heating

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Eco August 2010 Cover Story

  1. 1. Ecolibrium AUGUST 2010 · VOLUME 9.7TH E OFFICIAL JOURNAL OF AIR AHHow living greenwalls improveindoor air quality Australian Institute achieving the Green Dream of Refrigeration Air Conditioning and Heating Tomorrow’s technology today September 16–17, 2010 Melbourne Please consider the environment and recycle this magazine if you are not going to keep it. Do you deserve NSW’s tallest Livin’ an award? green building the dream Print Post approval number PP352532/00001
  2. 2. EDITORIAL Thankyou Captain Obvious I can recall that not long into my “But given the very real benefits of good professional working life (as opposed IAQ, the potentially serious consequences to that seemingly endless period of of poor IAQ and the ability to design, character-building physical labour, construct and operate buildings with spiritually enlightening but financially good IAQ using existing knowledge unsatisfactory volunteer positions, and without incurring significant costs, internships and the like) I actually building owners, designers and other plucked up the courage to express an professionals need a better appreciation opinion among my new colleagues. of the importance of providing good IAQ in their buildings.” It was the type of environment where the ability to opine, to climb up on one’s In the story that begins on p.24, high horse, to give everyone an insight Dr Ronald Wood (surely an example into your way of thinking – and the more of nominative determinism) takes contrarian the better – was one of the a closer look at living green walls most highly regarded of skills. and the role they can play in improving work environments. And I can’t remember the exact nature of my assertion or even the subject matter Fascinatingly, many of the gains (sports, politics, culture – the topic in made in the field have resulted question was less important than the from NASA research. attitude) but I do remember the cutting You’d think too, that by now most Matt Dillon riposte from my boss: “Well thankyou buildings would have their controls Editor Captain Obvious”. operating and working as they should, Oh. Really? Was it that patently obvious, I but this is not the case. guideline will help achieve best practice remember thinking at the time? I thought Indeed, in an Australian first, AIRAH through the establishment of technical, that I’d bought something new and is in the throes of putting together the functional and commissioning standards refreshing to the table but evidently not. Australian Best Practice Guideline for for performance outcomes.” Perhaps the obvious is not always that, at Controls (DA28). It will be the go-to least not to me. Elsewhere in this issue we chat to resource for anyone associated with outgoing ASHRAE president Gordon For instance you’d think that making implementing controls in buildings. Holness, who believes that by getting indoor air quality (IAQ) as good as “Building controls are now more buildings to function as they are designed possible would be a no-brainer. important than ever,” says Mark – by correctly commissioning them and Yet when you check out this issue’s cover Mitchell, general managers, projects, recommissioning them on a continuing story you’ll see that’s not always the case. for A.G. Coombs, in the article. basis – and moving towards more peak- sensitive HVAC systems – the building “IAQ is not a primary design or building “It comes down to the difference industry can reduce the need for more management issue compared to function, between an HVAC system that simply power stations. cost, space, aesthetics and attributes such works, and a system that works while as location and parking,” said Andrew using the minimum amount of energy It’s obvious really.   ❚ Persily of the US National Institute – and controls are at the heart of that of Standards and Technology. difference. An Australian best practice4 E co l i b r i u m   •   AU G U S T 2 0 1 0
  3. 3. COVER FE ATURE Moss planted on this biowall at the University of Toronto is kept moist by water constantly running down the walls, which absorb contaminants from the air. The plant room One of the lessons provided by NASA research, writes Ronald Wood, is that closed environments, whether extraterrestrial or decidedly Earth-bound, can be substantially enhanced by nature’s life-support system: plants. In the beginning astronauts breathe – air not given the requirements of a single test subject for natural cleansing by the Earth’s complex 15 days. A Lockheed engineer (Nigel) Space missions rely totally on recycled ecosystem. volunteered for the test. air for breathing, because unlike building ventilation there is no possibility of NASA researcher Dr Bill Wolverton The primary objectives were: outside air introduction. said that the solution was natural. • Demonstrate the ability of a wheat Among the air revitalisation systems “If man is to move into closed crop to continuously provide the CO2 tested, NASA’s Advanced Life Support environments on Earth or in space,” removal and O2 supply functions for project successfully demonstrated the use Wolverton says, “he must take along the air revitalisation of a single human of plants for air revitalisation for humans, nature’s life support system: plants.” test subject for 15 days. and the robustness of the plant systems as • Demonstrate three different NASA commenced the subsequent part of a human life support system. methods of control of the O2 experimental program Closed Ecological NASA has also shown that plants can be Life Support Systems, which was part and CO2 concentrations integrated into regenerative life-support of the preparation for the Human for the human/plant system. systems and controlled to provide a Exploration and Development • Monitor populations of specific desired performance. of Space (HEDS) Mission. microorganisms important to human and plant health. In 1973 NASA scientists identified As part of this project, a test at the more than 100 VOCs in the air inside Johnson Space Centre in Houston was Eleven sq m of dwarf wheat plants the Skylab space station. These were conducted in a sealed chamber. The consumed the CO2 and generated O2 low-level emissions from synthetic idea was to demonstrate the use of equal to that required by one person materials recirculating in the air the plants to provide the air revitalisation over 24 hours.24 Eco l i b r i u m  •   AUGU S T 2 0 1 0
  4. 4. COVER FE ATUREWe have lift-off producing clean, purified air For comparison, the Property Council to complement conventional HVAC of Australia’s best-practice existingThis test clearly demonstrated how the air filtration. office building tenant light and powerplant system could be managed with consumption is 62.5kWh/m2 for aengineering input to achieve high-quality This is a practical example of industrial building in operation 10 hours a day,recycled air for astronauts to breathe. ecology - an industrial process involving 250 days a year.Three distinct control methods were a closed loop where waste becomes inputused: for new processes – as happens in nature. In an Australian first, engineering “ Indoor air quality is more• Optimised conditions for the plants than thermal comfort and for maximum photosynthetic consultants Umow Lai Associates, output – integrated physicochemical installed five living wall biofilters humidity; it is the air that systems to complement biological air that filter the indoor air in its penetrates into our lungs, revitalisation. tenancy, complementing the providing the vital life• Actively controlling the level of conventional air filtration (see Ecolibrium, September 2009). force: oxygen ” biological air revitalisation by modulating the photosynthetic photon The pay-off is a healthy work The NABERS (ABGR) 5 Star benchmark flux (light) to control the rate of environment with improved productivity, for office tenants is equivalent to 52kWh/ photosynthesis. reduced absenteeism, and a reduction in m2. Clearly, the energy consumption ‘flu virus impacts, a result of the mid- associated with biowalls is relatively• Passively controlling the level of minor, and represents minimal ongoing range relative humidity from the planted biological air revitalisation by limiting energy costs. walls. the amount of available CO2 to control the rate of photosynthesis. Canadian architecture firm Diamond and The biowall can move 0.1m3/m2/sec, and Schmitt Architects has installed biowalls coupled with the fact that typical systemSimilar to conventional industrial pressure drops are less than 75Pa, mainly into a number of projects, including thewaste gas stream air pollution from the diffusers rather than the wall, refurbishment of Cambridge City Hall,control (APC) technology, the it explains why biofilters are inexpensive with spectacular and effective results.process of bioremediation results in a to operate relative to other controlbiochemical change as contaminants technologies. The pressure drop acrossor pollutants are metabolised by Design implications the mechanical filters in a typical HVACmicro-organisms and broken downinto harmless, stable constituents, for architects system in a standard office building is generally less than or equal to 124Pa. Thesuch as CO2, water, and salts. and engineers pressure drop across a HEPA filter canBiological reactors are good at treating A living wall biofilter gives the option range from 250 – 500Pa.highly complex and highly variable of minimum code-compliant fresh-air Local filtration reduces unwanted gaseouswaste gas streams over a wide range rates, reducing the need for increased pollutant and particle re-circulation, withof contaminant concentrations and ventilation by filtering up to 0.1 m3/m2/ potential improvement in productivityloading rates, and the environmental sec while delivering high-quality fresh air from breathing cleaner air, whileengineering community increasingly to building occupants at low cost, either providing protection for the HVAChas recognised that the use of incorporated into the building’s air- components.bioreactors for the treatment of air handling system or as a free-standing unit.(for removal of odours and various There is no by-pass – all of the air goesvolatile compounds) often provides through the biofilter and low pressure Clear air,economic and operational benefits. drop provides energy savings. The money saving technology can have a substantial impact Cleaner air and money savings obviouslyLiving wall biofilter on the energy balance and air quality of sound like a good idea, but how can they a space, as well as reducing ventilation be achieved? Reducing the ventilation rateBased on the proven technology from rates, while protecting the components of is a good place to start.the NASA results and other plant-based the air-handling system.research, environmentally active gas- Usually, increasing the ventilation rate isphase biofilters have been developed A living wall biofilter has low operating intended to improve air quality. However,to deliver improved indoor air quality, and maintenance costs relative to irrespective of building ventilationremove air contaminants, reduce CO2 other filtration technologies. The water design, ventilation rates, dilution mixinglevels and promote the concept of best- recirculation pump for a planted wall and of building air, displacement ventilationpractice indoor air quality for the health the fan that moves the air through the with 100 per cent “fresh air”, or mixedand well-being of building occupants. system are the only two energy sinks in mode, inherently polluted outdoor air the system. combines and reacts with contaminantsA living wall biofilter is a vertical planted generated indoors, resulting in poorer airwall that actively draws contaminated The kWh/m2 floor area consumption for quality - even creating indoor smog in theindoor air through the planted wall. Here the water pump is 2, and the plenum fan presence of ozone (Weschler 2006).the photosynthesising plants and their is 0.2 for a total 2.2kWh/m2 floor area, forroot microorganisms break down the an open plan biowall ventilated floor area Building outdoor air intakes less thancontaminants to simple CO2 and water, of 450m2. 60m above ground level are associated AUGU S T 2 0 1 0   • Eco l i b r i u m 25
  5. 5. COVER FE ATURE with significant increases in health- Humans are convective heat sources reaction rates fast enough to compete related symptoms in office workers, with causing increased contaminant with ventilation rates (Weschler 2006). 40–140 per cent increased odds of this concentrations in the breathing zone, Conventional air filters do not remove occurring (US EPA Base Study 2008). with super micron particles up to 5-10 these gaseous air contaminants, and micron showing a “boomerang” effect Current ventilation standards, based are generally inefficient for the smaller (Bolster and Linden, 2007). historically on non-health-related respirable particulates. criteria, such as perception of odour, Displacement ventilation involves The disadvantage of conventional may not be health-protective (Mendell supplying “fresh” air from the air supply high-efficiency particle and chemical et al, 2008). diffusers located near the floor. The air filters are the high initial, operation and Although ventilation rates above 10l/ rises as it is heated and displaces the hot maintenance costs sec-person may reduce adverse health contaminated air to the ceiling, where it symptoms for building occupants, it is removed. comes at the cost of increased energy Are we measuring It is widely believed that low-energy usage. Doubling the ventilation rate displacement ventilation systems can be the right indoor increases costs by about 5 per cent. More better than traditional mixing systems air pollutants? than 40 per cent of primary energy is at removing contaminants from a space. “There is no quantitative definition of used for buildings in EU countries and in This is because there is a belief that these acceptable IAQ that can be necessarily met the US (Seppanen, 2008), and is likely to systems will use the same mechanism for by measuring one or more contaminants,” be similar in Australia. Bottom line: there contaminant removal as they do for heat ASHRAE Standard 62.1 states. is great potential for significant energy removal, where they are clearly conservation in the commercial building more efficient. “With thousands of chemical vapours, sector (Seppanen, 2008). particles and microbiological quanta “ that can be in the air, a direct measure Compliance with energy of these constituents is in practical The vital life force rating schemes does not terms impossible. Concentrations There is generally little individual choice of itself deliver clean, that affect humans are typically so over the quality of the ambient air that small that expensive instruments (and breathable air. Only high- we breathe indoors, or the total daily methodologies) are required. Moreover, exposure. performance filtration benchmark thresholds for safe levels are Indoor air quality is more than thermal can provide this ” generally unknown.” comfort and humidity; it is the air that Unlike ambient air, which has the NEPC The heat-extraction problem exploits penetrates into our lungs, providing the (National Environment Protection vital life force: oxygen. the natural stratification that develops, Council) and the NEPMs (National extracting the warmest air that naturally Ventilation alone cannot deal with Environment Protection Measures), sits at the top of the room. However, all types of contaminants in a room. indoor air quality has no coordinated there is no physical justification as to system of control, or even a single area Without effective high-quality filtration, why this location should correspond to of government (local, state or federal) increased “fresh air” simply increases the location of maximum contaminant taking responsibility for it. energy costs without a commensurate concentration. In fact, many times it does improvement in indoor air quality. not (Bolster and Linden, 2007). A major difference between indoor and outdoor environments is that for a given An increased ventilation rate may only volume of air there are far more surfaces be treating the symptoms rather than the Surface chemistry indoors. ~ 3 m2/ m3 vs. 0.01 m2 /m3. cause, and additional airflow from these ventilation modes substantially increases on building filters building operating costs, consuming as Loaded particulate filters contribute to “Low-environmental- reduced air quality. The surface area of much as 30 per cent of the total energy use (Seppanen, 2008). captured particles can easily approach impact” products 600m2 (for a filter area of 0.36m2). To achieve the maximum interior star Compliance with energy rating schemes rating, manufactured products with does not of itself deliver clean, breathable Increasing the outdoor flow rate increases relatively low environmental impact air. Only high-performance filtration can the source strength of the filter. are chosen to reduce the impact of provide this. To be able to breathe deeply toxic emissions. There are no clear is not a luxury it’s a necessity. The proportionality between pollution load and flow rate holds at airflows up to Australian standards, goals or guidelines and well above the flow rates commonly for pollutants that may be emitted The air we used in ventilation systems. by a product. breathe indoors Chemical reactions occur on filters Building materials emit a myriad of reactive constituents and secondary More than 50 per cent of the air we (filter cake) resulting in the formation products. breathe comes from contact with the floor of noxious compounds. For example, around us, with dust exposure up to eight ozone adsorption on particulates, ozone/ For instance, the US EPA advises “no- hours or more per day. limonene and ozone /alpha pinene have VOC” latex paint does not necessarily26 Eco l i b r i u m  •   AUGU S T 2 0 1 0
  6. 6. COVER FE ATUREmean no emissions. Linseed oil used as a drying agent in “lowVOC paints” can react with ozone, nitrogen oxides or hydroxides(usually from outside supply air) to form oxidation products thatare potentially irritating or harmful to health (Weschler 2006).Triphenyl phosphate is an additive flame retardant and/orplasticiser used in electronic goods such as visual display units.It is continually emitted into indoor air during normal computeroperations (500C), and has a documented allergenic effect(Carlsson et al 2000).There are more than 75 different brominated flame retardantsused commercially, some of which are additive or reactivecomponents in polymers such as polystyrene foams, high-impactpolystyrene.Various “green” or “ecological” materials chosen to mitigatehealth problems related to indoor air may actually becontributing to the problem as a consequence of chemicaltransformations.The analytical methods routinely used in indoor airinvestigations are missing “biologically relevant” compounds.The term “stealth pollutants” is being used to describe thesechemicals, which produce adverse health effects.Filtration for enhanced IAQASHRAE Standard 189.1 Standard for the Design of High-Performance Green Buildings (2010) with a proposed addendum62.1.c, will add performance-based air cleaning requirementsto the standard, for new buildings and major renovation projects.Doubtless this will improve indoor air quality through betterfiltration.The US Green Building Council LEED rating provides aninnovation credit for “enhanced IAQ”. The requirements for thiscredit are described as:• Modify industry technologies to create a composite filter that is not only capable of removing common particulate matter but also provides removal of gases that are commonly associated with military warfare or terrorism.• Provide an extremely high level of indoor air filtration by installing a four-stage air filtration system composed of 85 per cent efficient prefilter, 99.95 per cent efficient HEPA filter, and a carbon filter, and address associated pressure drops for the installation.• Demonstrate a comprehensive design approach that has quantifiable environmental benefits, including calculation of airborne contaminants that this system removes compared to traditional systems.The Green Building Council of Australia’s innovation categoryhas been introduced to recognise a strategy or technology thathas a significant environmental benefit, not otherwise awardedpoints by Green Star - Office Interiors.Prospects for better indoor airThe USEPA recently conducted a study to identify currentadvanced filtration technologies that could be used as a startingpoint for further developing an advanced air-filtration system fora building’s HVAC system to help remove biological agents from AUGU S T 2 0 1 0   • Eco l i b r i u m 27
  7. 7. COVER FE ATURE the building environment. (Assessment Although HEPA filters provide high allergenic flame retardant triphenyl of Advanced Building Air Filtration filtration efficiency, they are not phosphate in the indoor environment. Systems, November 2008). necessarily appropriate for HVAC Environmental Science and Technology, applications. As a general rule, existing Vol. 34(18), pp.3885-3889. “ Clearly, the energy HVAC systems cannot be upgraded to HEPA filters without a complete retrofit EPA 2008. Building Assessment Survey consumption associated and Evaluation (BASE) Study. of the air-handling system due to the with biowalls is relatively high pressure drop and potential leakage Washington, DC; U.S. Environmental minor, and represents associated with them. Protection Agency, Washington. DC. minimal ongoing High-efficiency filters (MERV 15 and 16) Mendell Mark J., Lei-Gomez Quanhong energy costs ” are recommended by filter manufacturers as a cost-effective alternative to HEPA and Apte Michael G., 2008, Ventilation (estimated three ways) and building – The advanced air filtration system should filters for maximum particulate removal. related symptoms in U.S. office buildings provide a lower pressure drop than – The U.S. EPA BASE study. Currently, there is no performance conventional high-efficiency particulate In; Proceedings Indoor Air 2008, 17-22 criteria established for HVAC air filters, with higher or equivalent August 2008 Copenhagen, Denmark, 158. filtration systems designed to protect efficiency and comparable or lower cost. building occupants against biological NASA Advanced Life Support Project The requirements were established agents because there are no defined “safe” considering two criteria: (a) has better levels of exposure to biological threat Ott WR. and Roberts JW. (1988) performance than the high-efficiency agents. “Everyday exposure to toxic pollutants” filters (MERV 14, 15, and 16) and (b) Scientific American, 278(2): 86-91. does not exceed the pressure-drop The very real Persily A. 2008. Development of a design limit that common HVAC systems can accommodate. benefits of good IAQ guide to improve building IAQ. In; Proceedings Indoor Air 2008, 17-22 August The performance requirements established Andrew Persily of the US National 2008 Copenhagen, Denmark, 857. were a 99.9 per cent removal efficiency for Institute of Standards and Technology, aerosols with a 1-µm diameter (optical and co-authors from ASHRAE, BOMA, Seppanen, O. 2008, Scientific basis diameter) and with a pressure drop of less USGBC, and USEPA, (Persily et al 2008), for design of ventilation for health, have put the case for improved indoor air productivity and good energy efficiency than 0.5 in. H2O (124Pa). quality very succinctly. In; Proceedings Indoor Air 2008, 17-22 “IAQ is still not a primary design or August 2008 Copenhagen, Denmark, 744. building management issue compared Living wall to function, cost, space, aesthetics and US EPA Final Report on the “Assessment of Advanced Building Air Filtration biofilters, attributes such as location and parking,” the authors say. Systems” November 2008. the benefits “But given the very real benefits of good Weschler C., 2006 Ozone’s impact on • A continuous supply of IAQ, the potentially serious consequences public health. Environmental Health fresh, clean breathable air of poor IAQ and the ability to design, Perspectives, 2006, 114, 1489. • An increase in the indoor construct and operate buildings with Wood RA, et al (2002) Potted plant- O2 levels and a reduction in good IAQ using existing knowledge growth media: interactions and capacities the concentration of CO2 and without incurring significant costs, in removal of volatiles from indoor air. • Protection of the air- building owners, designers and other J. Env.Hort and Biotech. 77 (1): 120-129. handling system’s professionals need a better appreciation components. of the importance of providing good IAQ • Reduces unwanted in their buildings.”  ❚ gaseous pollutant and particle re-circulation References • Relative humidities in the AS 1668.2:2002 The use of ventilation 40 per cent to 50 per cent About the author range, which are the least and air-conditioning in buildings. Director of Innovative Plant favourable to the survival ASHRAE 2009, Performance Technology, Dr Ronald Wood is of many viruses Measurement Protocols for Commercial an environmental scientist and • Reduced ventilation Buildings. consultant in indoor air quality requirements, resulting in improvement for the health and significant energy savings. Bolster, D. and Linden, P., 2007, well-being of building occupants. • Potential Green Star Contaminants in ventilated filling boxes, He is an expert on the role of IEQ credits. J. Fluid Mech., 591, 97 – 116. indoor plants reducing air-borne volatile organic pollutants. Carlsson H. et al., 2000. Video Display Email: iplant@plantscleanair.com Units: An emission source of the contact28 Eco l i b r i u m  •   AUGU S T 2 0 1 0
  8. 8. COVER FE ATUREA CambridgeeducationThere are plenty of lessons to be learned fromthe new Cambridge City Hall in Cambridge,Ontario (Canada), which was developed byDiamond and Schmitt Architects.The new Cambridge City Hall defines the civic precinct, whichconsists of five heritage buildings, including the original townhall built in 1857. Within this heritage context, the presence ofthe new city hall is established with an open and transparentglazed façade.A sky-lit central atrium acts as an interior public square. Cambridge City Hall atrium“The atrium features a four-storey plant wall bio-filter, a verticalhydroponic system that aids in providing exceptional indoor airquality,” say Diamond and Schmitt Architects, which designed Energy modelling was conducted at the beginning of designthe project. to optimise building orientation and massing design, to envelope, mechanical and electrical systems’ specificationsThe new Cambridge City Hall is the first LEED Gold (the to ensure appropriate consideration of first-time capitalequivalent to 5 Star Green Star) city hall in Canada. expense against life-cycle costing models. “The building automation system (BAS) ensures a comfortableLight and air condition for the new city hall,” the architects say.“Exemplary indoor air quality is achieved through the use of afour-storey living wall bio-filter in the atrium,” the architects say. Sensors and controls“Return air is directed through the living wall where a symbiotic “C02 sensors connected to the BAS send greater ventilationplant/microbe ecosystem consumes volatile organic compounds to occupied spaces and reduce ventilation to unoccupiedand other air contaminants. The cleansed and humidified air spaces, saving energy and providing good air quality,”is then distributed through the building ventilation system. the architects explain.Diamond and Schmitt Architects pioneered the use of bio-filter plant walls of this kind, aiding in the development of the The building has an independent weather station on its greenprototype and working to enhance their efficiency.” roof that relays information about the outside temperature, barometer and wind, which is tied into the monitoring systemsThe building’s design allows natural light to penetrate to enable efficient operations. All staff areas feature LEDdeep into the building. Skylights in the central, four-storey message boards to communicate to employees. Prompts toatrium provide abundant daylight and promote natural close the windows on extremely hot days and other messagesventilation. Operable windows throughout the building allow are conveyed to conserve energy and reduce cooling costs.light and cooler air to enter at low levels. More than 75 per Several energy-efficiency measures have been implemented incent of staff workspaces have access to operable windows the mechanical design including a high-efficiency modulatingand more than 95 per cent have views to the outside. gas boiler and a condensing water heater, glycol loop heat recovery, variable frequency drives on pumps and an energy-Energy use efficient chiller with free cooling mode.Cambridge City Hall has an energy cost performance of 42 The projected annual electrical energy consumptionper cent compared to the Canadian Model National Energy is 895 MJ/m2/year.Code for Buildings. A conservative estimate comparing For more information, go to www.dsai.caa standard building of the same size to the new City Hallresults in a $160,000 savings on energy per year.Strategies to help achieve energy savings include a This article originally appeared in the August 2010high-performance building envelope with energy- edition of Ecolibrium. It is reprinted with permission.efficient windows, increased insulation and sun www.airah.org.aushading to reduce the solar heat gain. AUGU S T 2 0 1 0   • Eco l i b r i u m 29

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