HVAC system size – getting it right

There is evidence that many heating, ventilating & air conditioning (HVAC) systems, installed in larger buildings, have more capacity than is ever required to keep the occupants comfortable. This paper explores the reasons why this can occur, by examining a typical brief/design/documentation process. Over-sized HVAC systems cost more to install and operate and may not be able to control thermal comfort as well as a “right-sized” system. These impacts are evaluated, where data exists. Finally, some suggestions are developed to minimise both the extent of, and the negative impacts of, HVAC system over-sizing, for example: • Challenge “rules of thumb” and/or brief requirements which may be out of date. • Conduct an accurate load estimate, using AIRAH design data, specific to project location, and then resist the temptation to apply “safety factors • Use a load estimation program that accounts for thermal storage and diversification of peak loads for each zone and air handling system. • Select chiller sizes and staged or variable speed pumps and fans to ensure good part load performance. • Allow for unknown future tenancies by designing flexibility into the system, not by over-sizing. For example, generous sizing of distribution pipework and ductwork will allow available capacity to be redistributed. • Provide an auxiliary tenant condenser water loop to handle high load areas. • Consider using an Integrated Design Process, build an integrated load and energy use simulation model and test different operational scenarios • Use comprehensive Life Cycle Cost analysis for selection of the most optimal design solutions. This paper is an interim report on the findings of CRC-CI project 2002-051-B, Right-Sizing HVAC Systems, which is due for completion in January 2006

Departures from cost-effectiveness recommendations: The impact of health system constraints on priority setting

The methods and application of cost-effectiveness analysis have reached an advanced stage of development. Many decision makers consider cost-effectiveness analysis to be a valid and feasible approach towards setting health priorities, and it has been extensively applied in evaluating interventions and developing evidence based clinical guidelines. However, the recommendations arising from cost-effectiveness analysis are often not implemented as intended. A fundamental reason for the failure to implement is that CEA assumes a single constraint, in the form of the budget constraint, whilst in reality decision-makers may be faced with numerous other constraints. The objective of this paper is to develop a typology of constraints that may act as barriers to implementation of cost-effectiveness recommendations. Six categories of constraints are considered: the design of the health system; costs of implementing change; system interactions between interventions; uncertainty in estimates of costs and benefits; weak governance; and political constraints. Where possible -and if applicable- for each class of constraint, the paper discusses ways in which these constraints can be taken into account by a decision maker wishing to pursue the principles of cost-effectiveness

Whole life sustainability

Ian Ellingham and William Fawcett, RIBA Publishing, London, 2013, 160 p., ISBN 978 1 85946 450 2, AUD 56.84, GBP 30.84, USD 51.1

Realising Intentions: An evaluation of green building rating tools for Australian buildings

With growing concerns for enhancing sustainability, much attention has being paid to benchmarking performance in buildings. This paper evaluates the effectiveness of three rating systems that have been widely adopted for over a decade in Australia namely: (i) mandatory compliance under Section J (Energy Efficiency provisions) in the National Construction Code of Australia (NCC), (ii) a voluntary design rating tool - Green Star, and (iii) a voluntary operational rating tool-National Australian Building Environmental Rating Scheme (NABERS). The paper builds on the authors’ experience in building performance simulation, rating tool design, practice consultancy and post occupancy evaluations of buildings. It presents a detailed analysis of the rating tools with respect to the alignment between what is being assessed, how it is assessed and administered and the impact on design process and performance outcomes in buildings. The paper assesses the successes and shortcomings of the rating tools to demonstrate the potential for design and post occupancy rating tools to influence market behaviour and building performance and argues for increasingly stringent approaches to get to net zero emissions

Effective natural ventilation in modern apartment buildings

This paper addresses the challenge of evaluating for natural ventilation in modern apartment buildings. A number of natural ventilation design rules of thumb from published literature are listed. Their incorporation into one code for Australia (the Residential Flat Design Code, or RFDC) and India (the National Building Code, or NBC), in relation to apartment buildings is examined. Practical limitations to converting these rules of thumb into effective natural ventilation systems for apartment building designs are discussed. Apartment designs in the moderate locations of Sydney, Australia and Bengaluru, India are also reviewed to assess their effectiveness for natural ventilation. Simulation analysis presented indicate large energy savings are possible if apartments are retrofitted/designed to the proposed code requirements and designs compliant with thumb rules are capable of delivering effective natural ventilation if users choose to operate the apartment in “free running mode” during times when the outside dry bulb temperatures lie in an appropriate band. The paper also discusses how sub-optimal design solutions, affluence and adaptation to more stringent thermal conditions can negate the potential for natural ventilation and calls for proactive efforts to maintain climate responsive design standards and education/policy to encourage the benefits of natural ventilation over airconditioning

Air conditioning, comfort and energy in india's commercial building sector

Before India's building sector can fulfil its CO2 abatement potential, it is imperative for new build projects, especially those which provide for commercial and public functions, to eschew the energy-intensive designs that characterized western commercial buildings of the 20th century. In the absence of an adaptive thermal comfort standard specifically for India's climatic and cultural context, the current trend is simply to design airconditioned buildings to meet the stringent ASHRAE and ISO "Class A" comfort specifications. This paper proposes a holistic Post Occupancy Evaluation (POE) study of a cross section of Indian office buildings purposively stratified across a range of energy intensities with diverse environmental control systems and design approach in different climatic zones to develop an adaptive thermal comfort standard. By climatically adapting indoor design temperatures, the standard will offer India a low-carbon development pathway for its commercial building sector without compromising overall comfort or productivity

How Do Biological Characteristics of Primary Intracranial Tumors Affect Their Clinical Presentation in Children and Young Adults?

We demonstrated the pattern in presentation of primary intracranial tumors in a population-based cohort of patients aged 0-24 years identified from the National Cancer Registry for England, using linked medical records from primary care and hospitals. We used generalized additive models to estimate temporal changes in presentation rates. Borderline and malignant tumors presented at a similar rate in primary care (6.4 and 6.6 consultations per 100 patients each month) and in hospital (3.4 and 3.6). Benign tumors presented earlier but less frequently (rate = 4.4 and rate ratio = 0.75, 95% CI = 0.60-0.93, in primary care; rate = 2.6 and rate ratio = 0.83, 95% CI = 0.77-0.89, in hospital). Many tumors began presenting shortly before their diagnosis, but less aggressive tumors were likely to present earlier in primary care. Earlier detection of less aggressive tumors in primary care may reduce the risk of complications and morbidity among survivors

Pattern of symptoms and signs of primary intracranial tumours in children and young adults: a record linkage study.

OBJECTIVE: To describe the age pattern and temporal evolution of symptoms and signs of intracranial tumours in children and young adults before diagnosis. DESIGN AND SETTING: A record linkage study using population-based data from the National Cancer Registry, linked to Clinical Practice Research Datalink (CPRD) and Hospital Episode Statistics (HES). PATIENT COHORT: Patients aged 0-24 years when diagnosed with a primary intracranial tumour between 1989 and 2006 in England. METHODS: Linked records of relevant symptoms and signs in primary care and hospitals were extracted from CPRD (1989-2006, 181 patients) and HES (1997-2006, 3959 patients). Temporal and age-specific changes in presentation rates before diagnosis of an intracranial tumour, for each of eight symptom groups, were estimated in generalised additive models. RESULTS: All symptoms presented with increasing frequency until eventual diagnosis. The frequency of presentation of raised intracranial pressure (ICP) to hospitals rose rapidly to 36.4 per 100 person-months (95% CI 34.6 to 38.4) in the final month before diagnosis in the entire cohort. Clinical features in primary care were less specific: the main features were visual disturbance (rate: 0.49 per 100 person-months; 95% CI 0.33 to 0.72) in newborns to 4-year-olds, headache in 5-year-olds to 11-year-olds (0.64; 0.47 to 0.88), 12-year-olds to 18-year-olds (1.59; 1.21 to 2.08) and 19-year-olds to 24-year-olds (2.44; 1.71 to 3.49). The predominant features at hospital admission were those of raised ICP: between 1.17 per 100 person-months (95% CI 1.08 to 1.26) in newborns to 4-year-olds and 0.77 (0.67 to 0.88) in 19-year-olds to 24-year-olds. CONCLUSIONS: Non-localising symptoms and signs were more than twice as common as focal neurological signs. An intracranial tumour should be considered in patients with relevant symptoms that do not resolve or that progress rapidly

Body satisfaction and physical appearance in gender dysphoria

Gender dysphoria (GD) is often accompanied by dissatisfaction with physical appearance and body image problems. The aim of this study was to compare body satisfaction with perceived appearance by others in various GD subgroups. Data collection was part of the European Network for the Investigation of Gender Incongruence. Between 2007 and 2012, 660 adults who fulfilled the criteria of the DSM-IV gender identity disorder diagnosis (1.31:1 male-to-female [MtF]:female-to-male [FtM] ratio) were included into the study. Data were collected before the start of clinical gender-confirming interventions. Sexual orientation was measured via a semi-structured interview whereas onset age was based on clinician report. Body satisfaction was assessed using the Body Image Scale. Congruence of appearance with the experienced gender was measured by means of a clinician rating. Overall, FtMs had a more positive body image than MtFs. Besides genital dissatisfaction, problem areas for MtFs included posture, face, and hair, whereas FtMs were mainly dissatisfied with hip and chest regions. Clinicians evaluated the physical appearance to be more congruent with the experienced gender in FtMs than in MtFs. Within the MtF group, those with early onset GD and an androphilic sexual orientation had appearances more in line with their gender identity. In conclusion, body image problems in GD go beyond sex characteristics only. An incongruent physical appearance may result in more difficult psychological adaptation and in more exposure to discrimination and stigmatization