Paul Gerard Tuohy

Development of an adaptive window-opening algorithm to predict the thermal comfort, energy use and overheating in buildings

This investigation of the window-opening data from extensive field surveys in UK office buildings demonstrates: (1) how people control the indoor environment by opening windows; (2) the cooling potential of opening windows; and (3) the use of an ‘adaptive algorithm’ for predicting window-opening behaviour for thermal simulation in ESP-r. It was found that when the window was open the mean indoor and outdoor temperatures were higher than when closed, but it was shown that nonetheless there was a useful cooling effect from opening a window. The adaptive algorithm for window-opening behaviour was then used in thermal simulation studies for some typical office designs. The thermal simulation results were in general agreement with the findings of the field surveys. The adaptive algorithm is shown to provide insights not available using non adaptive simulation methods and can assist in achieving more comfortable, lower energy buildings while avoiding overheating.

Twentieth century standards for thermal comfort: Promoting high energy buildings

The urgent need to reduce anthropogenic greenhouse gas (GHG) emissions in a bid to meet increasingly stringent GHG targets has focused the attention of scientists on the built environment. The reason is that nearly 50% of all the energy in the developed world is consumed in buildings and it is here that the easiest savings can be made. Although the theoretical trend in building regulations is to favour lower carbon buildings, in reality new buildings have typically become more energy profligate year after year. Much of this results from increased mechanization, poorer building fabric and design, and the resource consumption patterns. Modern thermal comfort standards are partly responsible for increased levels of energy consumption in buildings as well as for encouraging unhealthier, less comfortable buildings because they drive the designers towards higher use of air-conditioning. A first step towards the radical overhauling of our approach to the artificial conditioning of buildings is to revise these standards. This article describes the evolution of the current standards and the problems inherent in the buildings they shape and serve and then proceeds to propose new methods of regulating thermal comfort in a warming world in which the cost of energy is rising.

Twenty first century standards for thermal comfort: fostering low carbon building design and operation

Nearly 50% of energy consumed in the developed world is consumed in buildings. Despite regulation intent, many new buildings are energy profligate. Thermal comfort standards are partly responsible for this increase in consumption. In this volume, Roaf et al. have described the evolution of current comfort standards and problems inherent in buildings they shape, and have discussed two new methods of regulating thermal comfort in buildings which recognize human adaptation and have potential for reduced energy demand. These new methods incorporate adaptation through a fixed heating and cooling threshold approach (similar to Japanese Cool-Biz) or through heating and cooling setpoints calculated based on outdoor conditions (using CEN standard equations). The impact on comfort and energy demand of these new approaches is investigated for a London office building. Variables such as future climate, future building upgrades, setback temperatures, internal gains and ventilation are also explored. Adoption of the new approaches gave a 50% reduction in heating and cooling energy for the simulated office. The new approach together with optimized setback temperatures, ventilation strategies and higher efficiency equipment gives predicted heating and cooling energy demand close to zero. Recommendations for future regulation, design and operation of buildings are proposed.

Closing the gap in building performance: learning from BIM benchmark industries

It is clear that the current industry process needs to improve in order to routinely deliver comfortable low-carbon buildings. Overheating in buildings designed to be of low energy is one of the key symptoms of current problems. Many initiatives aim to improve building performance and the industry process. A selection of these initiatives are reviewed including: the EU Energy Performance of Buildings Directive; the Green Star, Leadership in Energy and Environmental Design, Building Research Establishments Environmental Assessment Method (BREEAM) and National Australian Building Environmental Rating Standards (NABERS) rating schemes; the Passivhaus standard; the Soft Landings process and Building Information Modelling (BIM). The BIM approach is being actively promoted based on the assertion that the building industry process has stagnated compared to other industries suggested as productivity benchmarks such as the electronics industry. This study highlights the potential role that could be played by BIM as a framework to address the performance gaps, and suggests that processes from the BIM benchmark industries should be investigated for potential adoption. The organizational context and processes of the electronics industry are described, and it is proposed that they could be usefully adapted to reduce the scale and impacts of the building industry performance gap. Key conclusions are that public domain performance data are important, and that the adoption of a quality systems approach will be required to deliver the intended performance in practice, eliminate overheating and avoid excess energy use.

Considering the impact of situation-specific motivations and constraints in the design of naturally ventilated and hybrid buildings

A simple logical model of the interaction between a building and its occupants is presented based on the principle that if free to do so, people will adjust their clothing or available building controls with the aim of achieving or restoring comfort and reducing discomfort. These adjustments are related to building design in two ways: first, the freedom to adjust depends on the availability and ease of use of control options; second, the use of controls affects building comfort and energy performance. The values of constraints are quantified for a range of existing buildings in Europe and Pakistan. The integration of the model within a design flow is proposed and the impact of different levels of constraints demonstrated. It is proposed that to minimize energy use and maximize comfort in naturally ventilated and hybrid buildings the designer should take the following steps: (i) provide unconstrained low-energy adaptive control options where possible, (ii) avoid problems with indoor air quality which provide motivations for excessive ventilation rates, (iii) incorporate situation-specific adaptive behaviour of occupants in design simulations, (iv) analyse the robustness of designs against variations in patterns of use and climate and (v) incorporate appropriate comfort standards into the operational building controls.

Are current design processes and policies delivering comfortable low carbon buildings

Gaps between intended and actual performance which impact on indoor environment, energy use and carbon emissions have been well documented and are nowhere more important than when they present in performance problems such as building overheating and consequent occupant discomfort and high energy running costs. Here, such gaps are explored through a review of relevant literature and related illustrative investigations. Key drivers of those performance gaps are identified and located in the stages of the building industry process. Three case studies, of one office and two houses, are provided, highlighting where faults arise and may or may not be effectively dealt with and the reasons why. These include faults at the Implementation, Validation and Operation stages and the paper concludes by summing up generic failings in the industry that lead into the following paper by the same authors that offers an approach and potentially effective solutions to reduce such performance gaps by correctly using a BIM approach to quality control in the construction industry.

Energy, Carbon and Cost Performance of Building Stocks: Upgrade Analysis, Energy Labelling and National Policy Development

Abstract The area of policy formulation for the energy and carbon performance of buildings is coming under increasing focus. A major challenge is to account for the large variation within building stocks relative to factors such as location, climate, age, construction, previous upgrades, appliance usage and type of heating/cooling/lighting system. Existing policy-related tools that rely on simple calculation methods have a limited ability to represent the dynamic interconnectedness of technology options and the impact of possible future changes in climate and occupant behaviour. The use of detailed simulation tools to address these limitations in the context of policy development has hitherto been focused on the modelling of a number of representative designs rather than dealing with the spread inherent in large building stocks. Further, these tools have been research-oriented and largely unsuitable for direct use by policy-makers, practitioners and, ultimately, building owners/occupiers. This chapter summarizes recent initiatives that have applied advanced modelling and simulation in the context of policy formulation for large building stocks. To exemplify the stages of the process, aspects of the ESRU Domestic Energy Model (EDEM) are described. EDEM is a policy support tool built on detailed simulation models aligned with the outcomes of national surveys and future projections for the housing stock. On the basis of pragmatic inputs, the tool is able to determine energy use, carbon emissions and upgrade/running costs for any national building stock or subset. The tool has been used at the behest of the Scottish Building Standards Agency and South Ayrshire Council to determine the impact of housing upgrades, including the deployment of new and renewable energy systems, and to rate the energy/carbon performance of individual dwellings as required by the European Commissions Directive on the Energy Performance of Buildings (EC, 2002).

Co-designing the next generation of home energy management systems with lead-users

Home energy management systems are widely promoted as essential components of future low carbon economies. It is argued in this paper that assumptions surrounding their deployment, and the methods used to design them, emerge from discredited models of people and energy. This offers an explanation for why their field trial performance is so inconsistent. A first of a kind field trial is reported. Three eco communities took part in a comprehensive participatory design exercise as lead users. The challenge was to help users synchronise their energy use behaviours with the availability of locally generated renewable energy sources. To meet this aim, a set of highly novel Home Energy Management interfaces were co-designed and tested. Not only were the designs radically different to the norm, but they also yielded sustained user engagement over a six-month follow-up period. It is argued that user-centred design holds the key to unlocking the energy saving potential of new domestic technologies, and this study represents a bold step in that direction.

Occupant Interactions and Effectiveness of Natural Ventilation Strategies in Contemporary New Housing in Scotland, UK

The need to reduce carbon emissions and fuel poverty has led to increased building envelope air tightness, intended to reduce uncontrolled ventilation heat losses. Ventilation strategies in dwellings still allow the use of trickle ventilators in window frames for background ventilation. The extent to which this results in “healthy” Indoor Air Quality (IAQ) in recently constructed dwellings was a concern of regulators in Scotland. This paper describes research to explore this. First a review of literature was conducted, then data on occupant interactions with ventilation provisions (windows, doors, trickle vents) gathered through an interview-based survey of 200 recently constructed dwellings, and measurements made on a sample of 40 of these. The main measured parameter discussed here is CO2 concentration. It was concluded after the literature review that 1000 ppm absolute was a reasonable threshold to use for “adequate” ventilation. The occupant survey found that there was very little occupant interaction with the trickle ventilators e.g., in bedrooms 63% were always closed, 28% always open, and in only 9% of cases occupants intervened to make occasional adjustments. In the measured dwellings average bedroom CO2 levels of 1520 ppm during occupied (night time) hours were observed. Where windows were open the average bedroom CO2 levels were 972 ppm. With windows closed, the combination of “trickle ventilators open plus doors open” gave an average of 1021 ppm. “Trickle ventilators open” gave an average of 1571 ppm. All other combinations gave averages of 1550 to 2000 ppm. Ventilation rates and air change rates were estimated from measured CO2 levels, for all dwellings calculated ventilation rate was less than 8 L/s/p, in 42% of cases calculated air change rate was less than 0.5 ach. It was concluded that trickle ventilation as installed and used is ineffective in meeting desired ventilation rates, evidenced by high CO2 levels reported across the sampled dwellings. Potential implications of the results are discussed.

The potential impact of policy and legislation on the energy demands of UK buildings and implications for the electrical network

Chapter describes the potential impact of policy and legislation on the energy demands of UK buildings and implications for the electrical network.