Dimensioning a energy system for the new school in Jumkil : implementing geothermal heat pump, photovoltaic system and battery storage

The purpose of this study is to develop a modern and energy efficient system solution for a school in Jumkil, combining solar power, battery storage and geothermal heat pump system. By using models, simulations and available literature the study examines the dimensions of the included components for optimal coverage of the schools energy demand. The type of solar cells used is monochrystalline silicon solar cells and from an economical point of view, the installed effect should be 55 kWp. For such a solution the optimal battery capacity is 60 kWh and the battery technique used is vanadium redox flow battery. The vanadium redox flow battery technique is safe, have a long lifetime as well as a high depth of discharge. Implementing a smaller photovoltaic plant of 22 kWp reduces the need of battery capacity to 20 kWh. The battery is used for several applications, for example storage of the excess solar production and reducing the power peaks to eliminate expensive charge. An inverter heat pump of 79 kW is installed to cover the heat demand. The study also shows that a geothermal automatically controlled heat pump combined with floor heating is the best combination to reduce electricity costs annually. In interaction with the self-produced power and the vanadium redox flow battery the system allows the school to reduce their electricity consumption and thus the need of buying power from the grid decreases.Syftet med studien är att designa en modern och energieffektiv systemlösning för en skola i Jumkil där systemlösningen består av en solcellsanläggning, ett batterilager och en varvtalsstyrd värmepump. Genom att använda modeller, simuleringar och tillgänglig litteratur undersöker studien vilka dimensioner de olika komponenterna bör ha för att täcka skolans värme- och elbehov. Solcellerna som implementeras är av typen monokristallina kiselsolceller och från ett ekonomiskt perspektiv bör den installerade effekten vara 55 kWp. För en sådan lösning är den optimala batterikapaciteten 60 kWh och är av typen flödesbatteri. Fördelarna med flödesbatterier är att de är säkra, har lång livslängd och stort urladdningsdjup. Om en mindre solcellsanläggning med en installerad effekt på 22 kWp installeras kan batterikapaciteten reduceras till 20 kWh. Batteriet används bland annat för att lagra överskottet av producerad solel och för att kapa effekttoppar vilket minskar kostnaderna för inköpt el. Även en bergvärmepump med en effekt på 79 kW installeras för att täcka värmebehovet. Studien visar att kombinationen av bergvärmepumpen och golvvärme är det bästa sättet att minska årliga elkostnader. Tillsammans med den egenproducerade elen och flödesbatteriet kan skolan minska sin elförbrukning och på så sätt minska behovet av att köpa el från nätet

Outcome of primary resurfacing hip replacement: evaluation of risk factors for early revision: 12,093 replacements from the Australian Joint Registry

BACKGROUND AND PURPOSE: The outcome of modern resurfacing remains to be determined. The Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) started collection of data on hip resurfacing at a time when modern resurfacing was started in Australia. The rate of resurfacing has been higher in Australia than in many other countries. As a result, the AOANJRR has one of the largest series of resurfacing procedures. This study was undertaken to determine the results of this series and the risk factors associated with revision. PATIENTS AND METHODS: Data from the AOANJRR were used to analyze the survivorship of 12,093 primary resurfacing hip replacements reported to the Joint Replacement Registry between September 1999 and December 2008. This was compared to the results of primary conventional total hip replacement reported during the same period. The Kaplan-Meier method and proportional hazards models were used to determine risk factors such as age, sex, femoral component size, primary diagnosis, and implant design. RESULTS: Female patients had a higher revision rate than males; however, after adjusting for head size, the revision rates were similar. Prostheses with head sizes of less than 50 mm had a higher revision rate than those with head sizes of 50 mm or more. At 8 years, the cumulative per cent revision of hip resurfacing was 5.3 (4.6-6.2), as compared to 4.0 (3.8-4.2) for total hip replacement. However, in osteoarthritis patients aged less than 55 years with head sizes of 50 mm or more, the 7-year cumulative per cent revision for hip resurfacing was 3.0 (2.2-4.2). Also, hips with dysplasia and some implant designs had an increased risk of revision. INTERPRETATION: Risk factors for revision of resurfacing were older patients, smaller femoral head size, patients with developmental dysplasia, and certain implant designs. These results highlight the importance of patient and prosthesis selection in optimizing the outcome of hip resurfacing

Joint registry approach for identification of outlier prostheses

Background and purposeJoint Replacement Registries play a significant role in monitoring arthroplasty outcomes by publishing data on survivorship of individual prostheses or combinations of prostheses. The difference in outcomes can be device- or non-device-related, and these factors can be analyzed separately. Although registry data indicate that most prostheses have similar outcomes, some have a higher than anticipated rate of revision when compared to all other prostheses in their class. This report outlines how the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) has developed a method to report prostheses with a higher than expected rate of revision. These are referred to as "outlier" prostheses.Material and methodsSince 2004, the AOANJRR has developed a standardized process for identifying outliers. This is based on a 3-stage process consisting of an automated algorithm, an extensive analysis of individual prostheses or combinations by registry staff, and finally a meeting involving a panel from the Australian Orthopaedic Association Arthroplasty Society. Outlier prostheses are listed in the Annual Report as (1) identified but no longer used in Australia, (2) those that have been re-identified and that are still used, and (3) those that are being identified for the first time.Results78 prostheses or prosthesis combinations have been identified as being outliers using this approach (AOANJRR 2011 Annual Report). In addition, 5 conventional hip prostheses were initially identified, but after further analysis no longer met the defined criteria. 1 resurfacing hip prosthesis was initially identified, subsequently removed from the list, and then re-identified the following year when further data were available. All unicompartmental and primary total knee prostheses identified as having a higher than expected rate of revision have continued to be re-identified.InterpretationIt is important that registries use a transparent and accountable process to identify an outlier prosthesis. This paper describes the development, implementation, assessment, and impact of the approach used by the Australian Registry.Richard N de Steiger, Lisa N Miller, David C Davidson, Philip Ryan and Stephen E Grave

Improving the energy performance of an historic building : A study of the tradeoff between cultural heritage and energy performance

In order to reduce the energy consumption of buildings some degree of alteration usually needs to be done to its shell and construction, which can change the appearance of the building. At the same time buildings often carry materials, details, construction methods, and other historically significant artifacts, that are important to perserve. This often leads to compromises having to be made between improvements to energy performance, and the perservation of the cultural heritage of the building. In this project, a building from the late 1800s in Söderhamn, Sweden, was analyzed to find appropriate energy saving measures while also taking its cultural history into consideration. The simulation software VIP Energy was used to build a model of the house where simulations of different energy saving measures as well as different cases of occupant behaviour could be tested. From these tests, measures were selected and sorted into three packages depending on their level of energy reduction, invasiveness of cultural heritage, and overall complexity. Package A had the lowest energy reduction, but also the lowest invasiveness and complexity of the three. Package C had the highest energy reduction, but with next to no regard for the cultural heritage of the building, nor the complexity of implementing the measures in it. Package B was chosen to contain the measures that according to the authors sucessfully strike a balance between energy effectiveness and the perservation the building’s cultural heritage. The model of the building without measures implemented had a primary energy value of 181kW h/m2, an energy usage of 117 kW h/m2, and a thermal conductivity of 0.504 W/m2K. With package B implemented, the primary energy value was reduced to 54.3 kW h/m2, the energy usage to 32.4 kW h/m2, and the thermal conductivity to 0.247 W/m2K, which makes the building live up to the current standards set by the National Board of Housing, Building and Planning. With proper occupant behaviour, the primary energy value and the energy usage could be further reduced to 24.5 kW h/m2 and 32.4 kW h/m2 respectively. Our results suggest that large energy improvements can be made to buildings similar to this one, and that occupant behaviour is a big uncertainty when energy simulations on buildings are performed

Improving the energy performance of an historic building : A study of the tradeoff between cultural heritage and energy performance

In order to reduce the energy consumption of buildings some degree of alteration usually needs to be done to its shell and construction, which can change the appearance of the building. At the same time buildings often carry materials, details, construction methods, and other historically significant artifacts, that are important to perserve. This often leads to compromises having to be made between improvements to energy performance, and the perservation of the cultural heritage of the building. In this project, a building from the late 1800s in Söderhamn, Sweden, was analyzed to find appropriate energy saving measures while also taking its cultural history into consideration. The simulation software VIP Energy was used to build a model of the house where simulations of different energy saving measures as well as different cases of occupant behaviour could be tested. From these tests, measures were selected and sorted into three packages depending on their level of energy reduction, invasiveness of cultural heritage, and overall complexity. Package A had the lowest energy reduction, but also the lowest invasiveness and complexity of the three. Package C had the highest energy reduction, but with next to no regard for the cultural heritage of the building, nor the complexity of implementing the measures in it. Package B was chosen to contain the measures that according to the authors sucessfully strike a balance between energy effectiveness and the perservation the building’s cultural heritage. The model of the building without measures implemented had a primary energy value of 181kW h/m2, an energy usage of 117 kW h/m2, and a thermal conductivity of 0.504 W/m2K. With package B implemented, the primary energy value was reduced to 54.3 kW h/m2, the energy usage to 32.4 kW h/m2, and the thermal conductivity to 0.247 W/m2K, which makes the building live up to the current standards set by the National Board of Housing, Building and Planning. With proper occupant behaviour, the primary energy value and the energy usage could be further reduced to 24.5 kW h/m2 and 32.4 kW h/m2 respectively. Our results suggest that large energy improvements can be made to buildings similar to this one, and that occupant behaviour is a big uncertainty when energy simulations on buildings are performed

The influence on wound contraction and fluid evacuation of a rigid disc inserted to protect exposed organs during negative pressure wound therapy.

The use of a rigid disc as a barrier between the wound bed and the wound filler during negative pressure wound therapy (NPWT) has been suggested to prevent damage to exposed organs. However, it is important to determine that the effects of NPWT, such as wound contraction and fluid removal, are maintained during treatment despite the use of a barrier. This study was performed to examine the effect of NPWT on wound contraction and fluid evacuation in the presence of a rigid disc. Peripheral wounds were created on the backs of eight pigs. The wounds were filled with foam, and rigid discs of different designs were inserted between the wound bed and the foam. Wound contraction and fluid evacuation were measured after application of continuous NPWT at -80 mmHg. Wound contraction was similar in the presence and the absence of a rigid disc (84 ± 4% and 83 ± 3%, respectively, compared with baseline). Furthermore, the rigid disc did not affect wound fluid removal compared with ordinary NPWT (e.g. after 120 seconds, 71 ± 4 ml was removed in the presence and 73 ± 3 ml was removed in the absence of a disc). This study shows that a rigid barrier may be placed under the wound filler to protect exposed structures during NPWT without affecting wound contraction and fluid removal, which are two crucial features of NPWT

Outcome of revision of unicompartmental knee replacement: 1,948 cases from the Australian Orthopaedic Association National Joint Replacement Registry, 1999-2008

Background and purpose: Despite concerns regarding a higher risk of revision, unicompartmental knee arthroplasty (UKA) continues to be used as an alternative to total knee arthroplasty (TKA). There are, however, limited data on the subsequent outcome when a UKA is revised. We examined the survivorship for primary UKA procedures that have been revised. Methods: We used data from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) to analyze the survivorship of 1,948 revisions of primary UKA reported to the Registry between September 1999 and December 2008. This was compared to the results of revisions of primary TKA reported during the same period where both the femoral and tibial components were revised. The Kaplan-Meier method for modeling survivorship was used. Results: When a primary UKA was revised to another UKA (both major and minor revisions), it had a cumulative per cent revision (CPR) of 28 and 30 at 3 years, respectively. The CPR at 3 years when a UKA was converted to a TKA was 10. This is similar to the 3-year CPR (12) found earlier for primary TKA where both the femoral and tibial components were revised. Interpretation: When a UKA requires revision, the best outcome is achieved when it is converted to a TKA. This procedure does, however, have a major risk of re-revision, which is similar to the risk of re-revision of a primary TKA that has had both the femoral and tibial components revised.Jacqueline R. Hang, Tyman E. Stanford, Stephen E. Graves, David C. Davidson, Richard N. de Steiger, and Lisa N. Mille

International survey of primary and revision total knee replacement

Purpose Total knee arthroplasty (TKA) is currently the international standard of care for treating degenerative and rheumatologic knee joint disease, as well as certain knee joint fractures. We sought to answer the following three research questions: (1) What is the international variance in primary and revision TKA rates around the world? (2) How do patient demographics (e.g., age, gender) vary internationally? (3) How have the rates of TKA utilization changed over time? Methods The survey included 18 countries with a total population of 755 million, and an estimated 1,324,000 annual primary and revision total knee procedures. Ten national inpatient databases were queried for this study from Canada, the United States, Finland, France, Germany, Italy, the Netherlands, Portugal, Spain, and Switzerland. Inpatient data were also compared with published registry data for eight countries with operating arthroplasty registers (Denmark, England & Wales, Norway, Romania, Scotland, Sweden, Australia, and New Zealand). Results The average and median rate of primary and revision (combined) total knee replacement was 175 and 149 procedures/100,000 population, respectively, and ranged between 8.8 and 234 procedures/100,000 population. We observed that the procedure rate significantly increased over time for the countries in which historical data were available. The compound annual growth in the incidence of TKA ranged by country from 5.3% (France) to 17% (Portugal). We observed a nearly 27-fold range of TKA utilization rates between the 18 different countries included in the survey. Conclusion It is apparent from the results of this study that the demand for TKA has risen substantially over the past decade in countries around the world