Are Naturally Ventilated Office Spaces Best For New Zealand Climate? Presented by: Dr. Eziaku O. Rasheed Massey University

NZ climate Most of New Zealand are estimated to exceed a mean 2 degrees temperature rise by 2090 and that average temperatures may rise by 1 degree by 2040. An insecure supply of electricity and greater cooling load. Buildings will require more energy for cooling systems that rely on electricity. Future-proof our buildings with adaptive opportunities for passive, low energy buildings NIWA. Climate Change Scenarios for New Zealand. https://www.niwa.co.nz/our-science/climate/information-and-resources/clivar/scenarios#regional. Accessed 30th April, 2017 Byrd H. Energy Climate Building: An introduction to Designing Future-Proof Buildings in New Zealand and the tropical Pacific. University of Auckland – Transforming Cities, 2012. Kwok, A.; Rajkovich N. Addressing climate change in comfort standards. Building and Environment 2010, 45, 18-22.

Green office spaces and Natural ventilation Green office spaces are purported to provide an indoor environment that is expected to be environmentally sustainable with a conducive IEQ for occupants’ use. Natural ventilation is an element that is often associated with environmental sustainability or Green architecture. wind and thermal buoyancy

Issue Despite various evidence that naturally ventilated spaces are environmentally sustainable and provide thermal comfort, it is not a popular indoor environment control system used in New Zealand office environments. Onyeizu, E. Can Architecture increase productivity? The case of green certified buildings. PhD Thesis, University of Auckland. 2014. Russell, A. P., & Ingham, J. M. Prevalence of New Zealand's unreinforced masonry buildings. Bulletin of the New Zealand Society for Earthquake Engineering 2010, 43(3), 182.

Aim we investigated why natural ventilation is not a common indoor environment control system in Green offices buildings in New Zealand

Objectives Objective 1: Ascertain whether the NZ Green building rating tool encourages natural ventilation in office spaces. Objective 2: Investigate experts opinion on the suitability of natural ventilation in NZ office spaces.

Significance to provide a background for further study on the implications of the use of natural ventilation to create resilient indoor environments for office buildings. the greater shift from dependence on mechanical systems to free running environmental control systems.

Method Reviewed the New Zealand Green Star rating tools with a focus on the criteria for thermal comfort in the Green Star Office 2009 version. Interviewed professionals who have researched on or worked with the concept of natural ventilation in the design of office spaces. Ten participants (academia and registered architects) The interview was carried out through a face-to-face meeting, skype call and email depending on the location of the respondents. Reviewed the New Zealand Green Star rating tools with a focus on the criteria for thermal comfort in the Green Star Office 2009 version. The purpose for this is to ascertain whether the criteria encourage the use of natural ventilation in Green office spaces. This is supported by an interview with professionals who have researched on or worked with the concept of natural ventilation in the design of office spaces. This group of participants was selected as they have sufficient knowledge and experience in this field. Ten participants (academia and registered architects) were interviewed from tertiary institutions and architectural firms in New Zealand with at least ten years’ experience in the field. The interview was carried out through a face-to-face meeting, skype call and email depending on the location of the respondents.

Credit Criteria Summary Findings: Objective 1 The NZ Green Star IEQ criteria for thermal comfort encourage air conditioning systems over natural ventilation. Ref No. Title Aim of Credit Credit Criteria Summary Points awarded IEQ-6 Thermal Comfort To encourage and recognise the use of thermal comfort assessments to guide design options. Up to three points are awarded where it is demonstrated that assessments have been made of thermal comfort levels and used to evaluate appropriate servicing options. The following Predicted Mean Vote (PMV) levels, calculated in accordance with ISO 7730, (or equivalent using Draft ASHRAE Comfort Standard 55 and "Developing an Adaptive Model of Thermal Comfort and Preference - Final Report on ASHRAE RP884"), must be achieved during Standard Hours of Occupancy and using standard clothing, metabolic rate and air velocity values for 90% of the year For mechanically ventilated and mixed-mode buildings: One Point = PMV levels are between -1 and +1 Two Points = PMV levels are between -0.75 and +0.75 and Three Points = PMV levels are between -0.5 and +0.5. For naturally ventilated buildings: Two Points = PMV levels are between -1 and +1 and Three points = PMV levels are between -0.75 and +0.75. - New Zealand Green Building Council, Green Star NZ Technical Manual (vs3.1) 2016. Available online: https://www.nzgbc.org.nz/Category?Action=View&Category_id=132 (Accessed 29/03/2017).

Thermal comfort criteria Temperature standards are based mainly on the Predicted Mean Vote (PMV) standards of comfort More points as the range of temperatures are narrowed Adaptive method follows the PMV approach sine points are awarded based on PMV measurements. Easier to obtain more points by merely installing HVAC equipment creates an imbalance The NZ Green Star tool requires temperature standards that are based mainly on the Predicted Mean Vote (PMV) standards of comfort. It allocates more points as the range of temperatures are narrowed (3 points for PMV levels between -0.5 and +0.5 for mechanically ventilated and mixed-mode buildings and -0.75 and +0.75 for naturally ventilated buildings). It is inferred that the Adaptive method follows the PMV approach sine points are awarded based on PMV measurements. While the points awarded for an air conditioning system is the same as those awarded for natural ventilation, the ease at which these points can be obtained by merely installing HVAC equipment creates an imbalance

PMV versus Adaptive Model LEGEND:   External environment Building Structure Building materials Air conditioning systems Optimum comfort levels of thermal environment based on PMV Model (promoted by NZ Green rating tool) Extreme IEQ Adaptive IEQ Flattening the curve towards a straight line (Optimum comfort levels of temperature) - Onyeizu, E. Can Architecture increase productivity? The case of green certified buildings. PhD Thesis, University of Auckland. 2014.

PMV model for NV office spaces? the PMV model is a ‘static’ model Unsuitable for naturally ventilated, or mixed mode buildings Difficult to meet this narrow specification of thermal comfort without HVAC even in relatively mild climatic zones like New Zealand Within the context of the high energy penalty that is incurred when near isothermal conditions are maintained.

Green office spaces An illustration of indoor environment control dilemma in Green buildings. Energy efficient passive control system on the right-hand side; monotonous mechanical control system on the left-hand side - Onyeizu, E. Can Architecture increase productivity? The case of green certified buildings. PhD Thesis, University of Auckland. 2014.

Findings: Objective 2 NV are best for New Zealand Climate In general occupants can work between 18 – 25 degrees Personal control – occupants interaction with the indoor environment – active not passive occupants NV have low environmental impact Less pollution Less energy usage NV have lower operation costs Low maintenance Less reliance on HVAC

Factors affecting NV in New Zealand Occupant Satisfaction Limited by the size and layout of the office Individual offices have higher occupant satisfaction than large open-plan offices Let in unwanted elements – wind, cold, excess heat, fumes, noise etc. Design More complex to design Consideration of more factors e.g. rise in outdoor temperature, noise, lighting etc. Required high skills and creativity Not suitable for high rise buildings – upper-air wind Cost More initial cost to reach adequate thermal comfort through passive design

Conclusion NZ Green Star IEQ criteria for thermal comfort do not encourage naturally ventilated office buildings Perhaps if the NZ Green Star IEQ criteria for thermal comfort can be amended to promote the adaptive model that encourages natural ventilation, more designers could be interested in adopting this model. experts in this field prefer naturally ventilated office buildings to air conditioned ones. naturally ventilated office buildings are more complex to design amongst other factors that require consideration.