Jonathan Dewsbury

Extensions To Standard Hold Time Calculations

The paper extends existing methods of calculating the hold time for a fire extinguishing gas in an enclosure to cover mechanical HVAC systems and wide descending interfaces, and compares the wide descending interface models predictions with some experimental data. A simple approximation to the measured wide descending interface gives conservative hold time predictions, while the sharp descending interface model used in current standards gives optimistic predictions.

Thermal performance of a typical residential Cyprus building with phase change materials

This work investigates the thermal performance of a typical building in Cyprus, and the effect of application of a particular passive technology (phase change material or PCM) with the aim of reducing indoor air temperatures and energy supplied for the cooling season. Phase change materials for passive building applications are an emerging technology and have not been tested for the buildings of Cyprus, either by computer simulation or practical application. In this paper, the effect of incorporating a phase change material wallboard with a phase change temperature of 26℃ was investigated by simulation in Energy Plus. Four scenarios were considered for the same building geometry, each having different constructions. Two construction styles were used: perforated clay brick walls with reinforced concrete slabs and cellular concrete block walls with cellular concrete slabs. Each construction style was used in two different thicknesses. Simulations were carried out for the city of Larnaca for the cooling season only (May–October). The results showed that with this particular phase change material product, indoor air temperatures and cooling energies supplied to the building could be reduced by up to 1.7℃ and 14.0%. Practical application : Sensible heat storage in building fabric is usual practice in Cyprus, as traditional building materials are thermally heavy. This paper will have practical impact as it introduces application of PCMs, a new method for storing heat in the buildings of Cyprus in much lighter way, where the weight is significant constraint due to earthquake load.

The 'bin' method - a procedure for predicting seasonal energy requirements in buildings

Manual methods for calculating space heating energy requirements in buildings are briefly described and compared. An alternative method originating in the USA is introduced and some advantages over other methods are described. Tables of data are presented to allow ‘bin’ method calculations to be performed for UK weather conditions for space heating and air conditioning applications. The application of the method to continuous and intermitttent heating and air conditioning regimes is discussed. Examples are given of the use of the ‘bin’ method.

Simulation and real weather data: A comparison for Cyprus case:

This paper compares three sets of weather data for Cyprus and investigates the relationship between similarity of weather data and similarity of building heating and cooling loads. A building energy simulation weather file containing a year of hourly values of typical weather data for Larnaca was compared with 10 years of daily mean data (dry bulb temperature, global solar radiation, wind speed and relative humidity) for two other locations (Kyrenia and Nicosia). This was done by reducing the hourly data to daily mean values, generating the cumulative distribution functions of the three data sets and calculating the Finkelstein-Schafer statistics as a measure of similarity. It was found that the data for Larnaca were similar to that for Kyrenia and Nicosia, and most similar to that for Nicosia. The relationship between similarity of weather data, as measured by the Finkelstein-Schafer statistic, and the space heating and cooling loads of a simulated simple building was then investigated for some locations in the Mediterranean region. It was found that there was no apparent relationship between the Finkelstein-Schafer statistics and the total heating and cooling loads, but that there was a clear relationship between the Finkelstein-Schafer statistics and the heating and cooling loads considered separately. It is concluded that: the Finkelstein-Schafer statistic is a useful measure of similarity when comparing weather data sets; it is important to consider space heating and cooling loads separately, not just total load; comparing weather data for Palermo, Cairo and Jerusalem with that for Larnaca, a smaller value of the Finkelstein-Schafer statistic is associated with more similar heating and cooling loads; the Finkelstein-Schafer statistics are smaller for Kyrenia and Nicosia than for Palermo, Cairo and Jerusalem, so weather data for Larnaca can be considered for use in building energy simulation studies for Kyrenia and Nicosia. Practical application: There are many simulation weather data files available for different locations that can be used for dynamic thermal simulations of buildings. Yet, it is not practical to generate weather data file for every location. This work suggests that if a building energy simulation weather data set for a location is not available, then similar data for another location can be used, provided that FS statistic is small between the locations. This comparison has been performed for three locations in Cyprus in this work.

AC pressurisation: Fourier analysis and the effect of compressibility of air

The AC pressurisation method of measuring the airtightness of buildings is briefly described. Using a simplified model, the leakage characteristics of the enclosure may be found by Fourier analysis of the pressure signal if the effects of compressibility and flexing are neglected. These effects become small at low frequency, but the frequency required to make them negligible may be too low for the available instruments (low-frequency microphones) and the resulting pressure signal may be smaller than appropriate for building airtightness measurements. The conditions under which the other approximations in the model may be justified are not yet known.

AC pressurisation: Analysis by non-linear optimisation

The paper briefly describes the AC pressurisation method of building airtightness measurement and the disadvantages of earlier analysis methods. A new analysis method is described, based on fitting a non-linear function of the unknowns to data. The function is derived from the differential equations of the system components. The new method performed well with simulated data. With real data, the method produced good estimates of the leakage flow rate at 4 Pa pressure loss, leakage length/area and enclosure flexing, but poor estimates of the leakage exponent. It is suspected that this problem was due to measurement errors.

Lifecycle cost analysis for better air conditioning choice in Kuwait residential sector

Residential air conditioning consumes a huge amount of the produced electrical power from fossil fuel power plants in Kuwait. Energy availability and the consequences on Kuwait’s expenditure associated with producing electricity is a hot topic in this oil producing country. The predominant air conditioning type in Kuwait’s residential sector is packaged direct expansion. An intention to shift to chilled water air conditioning system for future’s houses was announced as a promising solution to save energy. This work is presented to demonstrate how lifecycle cost analysis can be performed to underline tentative issues before shifting to a new air conditioning system for houses in Kuwait. No previous attempts have been made to assess the feasibility of chilled water air conditioning system for houses in Kuwait based on lifecycle cost analysis. The work considered the air conditioning requirements for a block of six typical houses as a baseline for the evaluation. The total cooling load of the studied block of houses was used to estimate the annual electrical energy associated with each air conditioning alternative. This was made by the help of DOE EnergyPlus thermal simulation engine through its interface with DesignBuilder software. Actual financial inputs were penetrated in the analysis; which includes installation, operation and maintenance costs for each studied air conditioning alternative. It was found that chilled water system can conserve about 40% of the annual electrical energy required to operate packaged direct expansion air conditioning. But, due to high installation cost, chilled water system is not cost effective for consumers. The outcomes from the lifecycle cost analysis indicated that it would be cost effective for the government to subsidy the installation of chilled water systems for consumers. This will help to conserve electrical energy associated with conventional systems that are currently in use.Copyright

A combined cycle power plant with absorption cooling for houses air conditioning

This study examined the viability of a single-effectwater/lithium bromide absorption chiller driven by steamextracted from the steam turbine in the configuration of acombined cycle power plant (CCPP). System performance wasverified based on the annual cooling load profile of 1,000typical houses in Kuwait obtained from DesignBuilder buildingsimulation software. Computer models that represented a CCPPwith an absorption chiller and a CCPP with a Direct-Expansion(DX) air conditioning system were developed usingEngineering Equation Solver software. The computer modelsinteracted with the cooling load profiles obtained fromDesignBuilder. Analysis shows that the CCPP with theabsorption chiller yielded less net electrical power to the utilitygrid compared to similar CCPPs giving electricity both to thegrid and to the Direct-Expansion air conditioning systems giventhe same cooling requirements. The reason for this finding isthe reduction in steam turbine power output resulting fromsteam extraction.

Energy and the implication of residential cooling in hot climates: Case study for developing effective solution for residential cooling demand in Kuwait

Global energy statistics showed that oil is the most sought after energy source in the world. The economic burden on countries that are dependent on oil to produce electricity is noteworthy. Residential cooling is a significant consumer of electricity produced by oil in major oil producing countries with hot climates conditions. For this, Kuwait was selected for further analysis. By analysing official annual electricity statistics in Kuwait, residential cooling consumes 58.4% of the total delivered electrical energy at peak time on a hot summer day. Accordingly, the paper investigated orientation and grouping patterns of future houses in Kuwait to determine their impact on cooling load and electrical energy consumption. The popular DOE EnergyPlus simulation engine, through its interface with DesignBuilder Software, was used to obtain the cooling loads of the future houses. It was found that efficient orientation and grouping of houses, which is a zero cost energy conservation measure, can lead to tangible savings for future houses with approximately

Hold time calculations for non-standard enclosures

US 33 million of power system capital costs, 15 GWh per year of electrical energy consumption and 11 kilotons per year of CO2 emissions.