Spelling suggestions: "subject:"massive house"" "subject:"assive house""
71 |
Stanovení výše ekonomického nájemného pro nízko energetické objekty / Determining the amount of economic rent for low-energy buildingsBetáš, Michal January 2016 (has links)
The task of the thesis is to determine the economic rent for passive residential building. Work first defines the essential terms related to the topic of economic rent, then it continues with theoretical determination of the economic rent, which consists of the costs and a reasonable profit. The determination of economic rent for residental Pasove building is done through inserting real values to a pre-described method of calculation. The result of diploma thesis is the determination of economic rents in number of 8 variants with varying degrees of capitalization levels and discount rates. Identified economic rents are finally compared by direct comparison with similar flats and evaluated.
|
72 |
Smart City objekty a jejich oceňování / Smart City Buildings and their ValuationUheríková, Eliška January 2017 (has links)
The diploma thesis focuses on specification of standard type buildings and Smart City buildings differences. Thesis also contain a history part of individual buildings category, including their specification. The aim of thesis is to determine designs for changes of building valuation in Smart City standard. Theoretical part contains basic definition and limitation of terms from civil engineering branch and structural types, summary of historical development of houses and evaluation by cost method, most common used experience. Practical part is focused on calculation. According real houses cost of three detached houses in Smart standard, there are calculated new price ratio which enter into cost method valuation. Their effectiveness is verified together with newly design adaptation of cost method valuation on next five detached houses in Smart standard.
|
73 |
Framtidens energieffektiva förskola : Gestaltning och formgivning av en naturförskola i passivhusteknik / The pre-school of tomorrow : Configuration and conformation of a nature-preschool in passive house technologyLööv, Sofia January 2013 (has links)
Daggkåpan är en förskola som projekterats i passivhusteknik. Förskolan är en naturförskola, vilket främst innebär att i stort sett all verksamhet bedrivs utomhus. Byggnaden är i två plan vilket gör att tomtarean kan utnyttjas till mer utomhusvistelse. Förutsättningar för att bedriva verksamheten inomhus finns även. Utomhusmiljön och inomhusmiljön hos Daggkåpan smälter samman och barnen kan lätt ta ett steg ut till naturen från sina hemvister. Detta innebär att antalet utgångar ökar. En solcellsanläggning genererar all elektricitet och gör byggnaden självförsörjande. Byggnadens varmvatten och värme står solfångare för. I takt med bostadsutvecklingen blir även behovet av förskolor större. Att skaffa kunskap och erfarenheter om energieffektivt byggande är idag en god idé eftersom alla byggnader på sikt måste vara så energieffektiva som möjligt. En av hörnpelarna med att bygga passivhus är att låta ett genomtänkt och energieffektivt byggnadsskal ersätta ett konventionellt värmeförsörjningssystem. Genom att förbättra konstruktioner och hålla koll på byggprocessen kan andra delar av byggnaden förenklas och i vissa fall helt ersättas. Det som fördyrar i ena änden kan leda till en god investering i den andra. Utmaningen med passivhus är att systematisera, se helheter och sammanhang och framför allt eftersträva det enkla. Enkla system ger låga drift- och underhållningskostnader och risken för driftstörningar minskar. Den största delen av värmen är gratis. Den kommer från instrålande sol, värme från människor och spillvärme från apparater och matlagning. Grundkravet är att byggnaden har ett värmeeffektbehov under 10 W per kvadratmeter vid +20ºC inomhus på årets kallaste dag, definierat av dimensionerande utetemperatur. Byggnaden får max läcka 0,3 l/s, m² oms vid +/- 50 Pa tryckskillnad. För att uppnå god komfort krävs välisolerade väggar, solavskärmningar, energieffektiva fönster och dörrar, små köldbryggor och ett bra ventilationssystem där värmen från insidan av huset återvinns. Antalet passivhus i Sverige ökar snabbt, men det är fortfarande småhusen som dominerar. Att bygga en förskola som passivhus är en god idé ur flera synvinklar; Bland annat för att de täta och välisolerade väggarna stänger ute buller och oljud. Även mellanväggar isoleras och bidrar till en extra tyst byggnad. Dessutom blir barnen miljömedvetna eftersom de får vara delaktiga i energieffektivisering. -En viktig aspekt för framtiden. Barnen bidrar själva till uppvärmning av lokalerna genom kroppsvärmen. Undersökningar har bland annat visat att barn som får vistas utomhus är friskare, mer självgående, mer kreativa och klokare. Det ultimata är att använda sig av utemiljöer som ett extra rum för förskolan. Detta leder till minskad byggnadsarea och mindre byggmaterial krävs. Pedagogiken Reggio Emilia använder sig just utav detta begreppet "Uterummet som ett extra rum för verksamheten". Barnen får därmed röra sig fritt i utemiljö, utveckla sina sinnen i en rik fantasivärld, inspireras och samverka med natur och hållbarhet. / Daggkåpan is a preschool projected in passive house technology. The preschool is a nature preschool, which means the activity is mainly out door. It is a two floor building which gives conditions to use the area for more outdoor activities. Conditions for drive the preschool indoors is possible as well. The garden and the inside rooms are connected to each other by the exterior rooms and it is easy for the children just to take a step out to the garden from their residences. A solar cell system generates electricity to the building and makes it self-supplied. The residential development leads to the need of preschools. To obtain knowledge of energy effective constructions is a good idea as the buildings in the future have to be as energy effective as possible. One of the most important things by use the passive house technology is letting a well measured and energy- effective building shell replace a conventional heat supply. By improvement of the construction and focus on the process other parts of the building can be simplified and some can be replaced. What is expensive in one end can lead to a good investment in the other. The challenges with passive house are to systematize, see whole parts and contexts and especially to seek after the simple. Easy systems give low operations- and service-costs and reduce fear of disruptions. Most of the heat is for free. It comes from insulation, human heat and heat from cooking and technologies. Basic requirements for this type of building is a need of heat-output under 10 W per square-meter at an indoor temperature of 20 degrees on the coldest day of the year, defined of the dimensioned outdoor- temperature. The maximum of leak is 0,3 liters per second and square meter at +/- 50 Pa. To receive high comfort it claims well-isolated walls, shadings, energy-effective windows and doors, small thermal bridges and a good ventilation-system where the indoor heat recycles. The number of Passive houses increases, dominated of small houses. Building a preschool as a passive house is a good idea from several perspective; the well-isolated walls leaves out the noise, even the intermediate walls isolates and contributes to a silent building. The children get environmentally conscious as well and take notes of the energy- effectively. - A very important aspect for the future. The children contributes them self of heat to the building by their body heat. Investigations has been shown that outdoor playing children is more healthy, self-propelled, more creative and more clever. The most ultimate is so use patios as an extra room for the preschool activities. The pedagogy Reggio Emilia uses this concept. The children can consequently feel free staying outside, developing their minds in an imaginative environment, inspired of the interaction of the nature and sustainability.
|
74 |
Energy saving opportunities in residential buildings: insights from technological and building energy code perspectivesLi, Bo 21 September 2020 (has links)
The residential building sector plays an important role in combating climate change in Canada. Many energy efficiency solutions along with new building energy standards have been implemented to improve building energy performance. However, their effects on energy saving and GHG emissions reduction vary due to the complexity of the building systems and the variability of their operational conditions. This work quantifies such variability in both energy efficiency devices and building energy standards implementation, respectively.
The first study in this dissertation assesses the energy savings from sensible heat recovery in a residential apartment suite in various locations across Canada. A series of detailed building energy performance models are developed in TRNSYS. The HVAC system’s annual energy consumption is simulated and the results are compared with and without HRV for each climate zone. The results show the heating energy savings of employing the HRV vary from 17 to 34% depending on the winter climatic conditions; while, the building cooling energy use can be increased due to the undesired thermal recovery occurring in the HRV during the cooling season.
The second study investigates the free cooling potential of outside air in various Canadian cities. A series of thermal models developed using BEopt 2.8 for a hypothetical single-family house with various window-to-wall ratios and building aspect ratios simulates hourly building cooling load profiles. The free cooling potential is analyzed by comparing the maximum available and the actual usable free cooling for various building features and different climates. The results indicate that, although free cooling is widely available in most areas of Canada during the summer and shoulder seasons, only 17-42% of such free cooling is usable without the use of thermal storage.
The last study examines the effects of two building energy standards - the BC Step Code and the Passive House criteria - on reductions in residential household space heating GHG emissions under different enforcement scenarios. The space heating energy and the GHG emissions are estimated using the forecast growth of single detached households for the period from 2020 to 2032. The results show that the space heating GHG emissions can be reduced by 77% and 89%, respectively if the BC Step Code or the Passive House criteria is implemented in Canada. It is also found the impacts of energy code on GHG emission mitigation are less significant in regions where the carbon intensity of the dominant heating fuels is low. / Graduate
|
75 |
Analýza nákladů zdrojů vytápění u pasivních domů / Cost analysis of heating sources in passive housesVítek, Marek January 2022 (has links)
The topic of this diploma thesis is cost analysis of heating sources in passive houses. The first part of the thesis is theoretical and focuses on basic concepts of passive house, renewable energy sources, heating sources, economical indicators. In the practical part there is cost analysis of chosen heatig sources of model house. Result of this thesis is evaluation of design options and optimal solution.
|
76 |
Architektonický výraz obytných staveb energeticky efektivní výstavby / Architectural expression of residential buildings in energy-efficient housingGerö, Jiří January 2013 (has links)
These days create an enormous pressure on energy savings because of their high prices. For future it is obvious that their prices will grow. Not only the representatives of European Union realize this fact, but basicaly common people who run their houses and pay the bills. For this reason low - energy houses respectively passive houses are in the limelight. Reasons of economy should not be the only criterion of quality, but its integral part, one of several components. Energy efficient housing is a response in architecture and building to turbulent global warming. The aim of the work is try to specify how to conceive an efficient building with respect to its architectural quality in the contect of directions coming from European Union and which should be implemented soon in the Czech republic. Will zero house become driving force of architecture in Europe in 21st century? The result of the work will be useful in orientation how to conceive an efficient house with respect to its aesthetical quality.
|
77 |
Šetrné bydlení na venkově / Environment-Friendly Housing in Rural AreasČáslava, Petr January 2013 (has links)
While I spent 7 years of study, experience and dedication to this work, the building construction has passed evolution from construction boom to contemporary building crisis. Demand for cheap building construction, materials and family housing increased sharply. Energy prices are rising every year... It seems that we will all have to deal with our essential task today or in the near future . This task is mean to prevent the current rate of degradation and destruction of our planet's climate and our environment. In this point of view, it looks the question of energy-saving construction very topical. By entering the study was to examine the possibilities of environmental friendly housing in rural areas in terms of environmental issues. My hypothesis was if can I determine the suitable candidate for the construction of passive houses themselves by comparing their characteristic of pre-defined construction samples. My objective is to offer builders and designers overview of suitable building systems with the possibility to compare the various factors influencing the decision on the selection of a builder´s construction for a house. The thesis presents the comparison of seven structural systems as a basic element of architecture. In the implementation of energy-efficient house is an architectural form often conditioned by structure. For this reason it is necessary to offer this kind of overview with options and parameters of individual building systems, which can then be used by architect to design a house for the builder - free and easy realization of his own, let´s say DIY (do it yourself). For builders (mean investors) of DIY houses is economy and finance a crucial question, therefore, for this reason I will evaluate suitable building system which is relative performance vs. price in the end. It is necessary to take into account the architecture of the house and especially the space layout and design and the attitude with the context of the rural areas environment. My pupose was to prove that good architectural design can be used with of low-cost, energy-saving and environmental friendly house built in DIY way.
|
78 |
Fuktrelaterade risker vid lågenergikonstruktion i lättbetong : En studie av ett nyproducerat passivhus / Moisture related risks with aerated concrete in low energy constructions : A study of a newly produced passive houseJansson, Sebastian, Niklasson, Erik January 2014 (has links)
Trenden i byggbranschen är att efterfrågan på täta, energisnåla byggnader ökar. Passivhus och andra lågenergikonstruktioner blir vanligare och vanligare. Riskerna med att bygga in organiskt material som trä i dessa konstruktioner har fått branschen att börja titta på alternativa material. Lättbetong är ett material som både har bärande och isolerande egenskaper. Dessutom är det inte organiskt vilket gör det okänsligt för mikrobiell påväxt. Det som är intressant med lättbetong, ur fuktsynpunkt, är att materialet levereras från tillverkare med en stor mängd byggfukt. Våren 2014 färdigställde Bollnäs Bostäder passivhus- projektet Sundsbro i Bollnäs, där lättbetong ingår i utfackningsväggarna. Sett inifrån består väggen av ett tunt lager kc-puts, lättbetong, cellplast, mineralull, kc-baserad grovputs och ytputs. I detta arbete användes projektet i Bollnäs som referensobjekt och en risk- och känslighetsanalys av väggkonstruktionen utfördes. Arbetet utreder risken för fuktrelaterade problem med väggen vid de extra uttorkningsinsatser som vidtogs i referensobjektet och vid normala uttorkningsbetingelser. Vidare utreds vilka parametrar som är viktiga för väggens fuktfunktion och vad man behöver tänka på när man projekterar och bygger i lättbetong. Arbetet har genomförts i samarbete med AK-Konsult Indoor Air AB och deras senior konsult Anders Kumlin. Fuktberäkningsprogrammet WUFI Pro 5.3 har använts för simuleringar. Beräkningarna gjordes endimensionellt på väggkonstruktionen. Resultaten med den ökade uttorkning som utfördes i referensobjektet visar inget högre fuktinnehåll längst ut i väggen på grund av byggfukt från lättbetongen som vandrar utåt. Farhågan var att så skulle kunna ske och att det skulle kunna leda till mögelproblem. Däremot visar resultaten att bygg-fukt från putsen kan fukta upp mineralullen. Det finns dock inga kända skadefall av detta slag och därför dras ändå slutsatsen att konstruktionen är riskfri. Tack vare en förutseende fukt-projektering och väl utförd uttorkning eliminerades risken för mögel. Hade inte dessa åtgärder vidtagits så visar resultaten att en liten mängd byggfukt hade kunnat vandra utåt och kondensera i mineralullen under första vintern. Då hade det funnits risk för mikrobiell påväxt. Detta visar att det är av största vikt att utföra en noggrann fuktprojektering vid byggnation av välisolerade hus i allmänhet och i synnerhet när lättbetong används. Lyckligtvis gjordes detta på ett bra sätt i referensprojektet. Känslighetsanalysen visar att isoleringens diffusionstäthet är avgörande för hur stor del av bygg-fukten som kan vandra utåt och därmed hur stor risken för problem blir. Lägre täthet ger större risk och högre täthet reducerar risken. Resultaten visar också att det är viktigt att inte montera täta skikt på insidan för tidigt. Den allmänna rekommendationen från leverantör är att lättbetongen skall torkas till 15 % fuktkvot på 50 millimeters djup innan målning och tapetsering på insida vägg får ske. Studien visar att detta är ett för högt fukttillstånd om det skikt som appliceras på insida vägg är tätt. Lättbetongen bör torkas till 5 % på 50 millimeters djup innan helt täta skikt kan monteras utan mögelrisk. / The trend in the construction industry is that the demand for tight, energy-saving buildings is rising. Passive houses and low energy constructions are becoming more and more common. The risk with using organic material in this type of constructions has made the industry look at alternative materials. Aerated concrete is a material that has both load-bearing and insulating properties. In addition to that it is not organic, which makes it insensitive to microbial growth. What is interesting with aerated concrete, from a moisture point of view, is that the material is delivered from the producer with a large amount of construction moisture. In the spring of 2014, the passive-house project Sundsbro in Bollnäs with aerated concrete in the wall construction, was finished by Bollnäs Bostäder. In this study the project in Bollnäs was used as reference object and a risk- and sensitivity analysis was made. The study examines the risk of moisture related problems with the wall construction during normal dehydration conditions and after the increased dehydration efforts that were taken in the reference project. The study also examines which parameters are important for the moisture function of the wall construction and what you need to think about when you project and build with aerated concrete. The job has been done in cooperation with AK-Konsult Indoor Air AB and their senior consultant Anders Kumlin. The moisture calculation program WUFI Pro 5.3 has been used for simulations. The results with the increased dehydration that was used in the reference project show no increased moisture content in the outer parts of the construction due to construction moisture from the concrete that wanders outwards. The concern was that so could happen and that it would lead to mould problems. However the results show that construction moisture from the exterior plaster can moisten the mineral wool. There are no known damage cases of this sort and therefore the conclusion is that the construction is free of risk. Thanks to a foreseeing moisture projection and a well performed dehydration the risk of mould was eliminated. If these measures would not have been taken, the results show that a small amount of construction moisture could have wandered outwards and condensed inside the mineral wool during the first winter. Then there would have been a risk of microbial growth. This shows that it is very important to carry out a detailed moisture projection when constructing well insulated houses in general and when using aerated concrete in particular. Fortunately this was properly done in the reference project. The sensitivity analysis shows that the diffusion resistance of the insulation decides how much of the construction moisture that can wander outwards and consequently the size of the problem risk. Results also show that it is crucial not to apply sealing layers on the inside of the wall too early. The general recommendation from the supplier is that the aerated concrete should be dried to 15 % moisture ratio on 50 millimeter depth before painting and paper hanging on the interior surface of the wall can be done. The study shows that the concrete still is too damp at that stage if the layer applied on the inside of the wall is impermeable. The concrete should be dried down to 5 % moisture ratio before sealing layers can be applied without mould risk.
|
79 |
Approaches to energy efficient building development : studying under Chinese contextsGu, Zhenhong January 2007 (has links)
This thesis presents a general description of approaches to energy efficient building development under Chinese contexts. The purpose of the work is to discuss how Chinese building development can be approved from an energy saving perspective. Building development is a complicated process that relates to many stakeholders’ interests. The developed countries have studied in this field extensively for several decades. Generally, the approaches to energy saving can be set at three levels: administration, construction industry and architectural design. More new strict codes for energy efficient buildings are being issued for enforcement. At the same time, many research institutes have developed Building Environmental Assessment (BEA) methods, where energy efficiency is an important factor in the models. Various technical solutions for energy efficiency are developed as well. The administrative approaches are not the main objective discussed in the thesis, though the importance of them is undeniable. BEA systems are not only assessment methods, but also market-based stimulating approaches for sustainability of construction market. Technical methods have been developed for a long period. Passive House and Low Exergy (LowEx) Systems are two representative examples in European countries. All of these approaches are relatively unfamiliar to Chinese architects and developers, let alone their effect and applicability. The thesis tries to analyse this situation and their applicability within Chinese context. In China to a certain project, the importance of technical issues is relatively recognized. However, a few successful individual cases in technique can not change the reality that most of new building development has failed in energy efficiency in China. This is a serious situation when China is in an enormous expansion phase in building new houses. The thesis tries to discuss the reasons for this phenomenon. One reason could be that the stakeholders in the developing process are not aware of the importance of collaboration which is the only method to get “Both Win” according to Game theory. The thesis discusses a paradigm to replace two traditional linear paradigms in building developing process. Architects should act as coordinators of different stakeholders rather than technical supporters. The thesis tries to discuss the propositional route of developing energy efficient buildings. Technical approaches are basic research, which presents the concepts that have been proved realizable; BEA encourages developers to develop more energy efficient buildings for economic benefit, which will make good demonstrations for whole market; national laws and policies are final approaches, which ensure that every project will have good performance of energy efficiency. When the old standardization and legislation are finished, a new cycle will begin with more advanced techniques. China government has started the progress to enhance energy efficiency. However, this process will be tough and slow. The thesis discusses Chinese special conditions and the problems that cry out for solution in the future. / QC 20101105
|
80 |
Utveckling av konventionella småhus till passivhus : En studie med analys av livscykelkostnader, förändring av boendekvaliteter och ett förslag till en alternativ utformningCarlsson, Elin, Sörebö, Victoria January 2018 (has links)
Klimatförändringarna blir allt mer omfattande i takt med att jordens befolkning ökar. Den negativa miljöpåverkan bottnar till stor del i användandet av råvaror och energiförbrukning vid skapandet av materiella ting. Enligt energimyndigheten (2015) står byggsektorn för ca 40 % av Sveriges totala energianvändning. För att minska energianvändningen har mål både på nationell och internationell nivå skapats. Målen är tänkta att skapa större förståelse av ett mer energieffektivt byggt samhälle för samtliga aktörer inom byggbranschen. En hållbar utveckling av husbyggandet kräver förutom att värna om miljön en beaktning av de ekonomiska och sociala aspekterna. I det här examensarbetet har det undersökts om två specifika standardhus från en småhusleverantör kan utvecklas till passivhus med bevarad arkitektonisk karaktär. Studien syftar delvis till att undersöka om begreppet passivhus kan fungera som ett hållbart koncept för byggandet av enfamiljshus. Begreppet hållbar utveckling har begränsats och en förenkling har applicerats i arbetet. Den ekologiska aspekten representeras av energiberäkningar och eventuella åtgärder för att standardhusen ska uppnå kraven för passivhus. Den ekonomiska aspekten representeras av en livscykelkostnadsanalys med hjälp av nuvärdesmetoden och återbetalningsmetoden. Den sociala aspekten representeras av en utvärdering av förändring i boendekvaliteter vid utveckling från ett standardhus till passivhus. Studien presenterar även en alternativ utformning av ett passivhus med avsikt att främja positiva boendekvaliteterna. Standardhusen tillhör en småhusproducent, Intressanta hus, som har sitt huvudsäte i Västerås. Husen utgörs av en villa på 147 m2 i ett plan med pulpettak samt en villa på 151 m2 i två plan med sadeltak. Med anledning av Intressanta hus geografiska läge har Västerås klimat använts som utgångspunkt vid energiberäkningarna. För att addera ytterligare en utmaning har även möjligheter för utveckling till passivhus undersökts för standardhusen i ett subarktiskt klimat i Kiruna. Västerås representerar därmed klimatzon III och Kiruna klimatzon I. Resultaten avslöjade att det är möjligt att utveckla standardhuset i två plan med sadeltak till passivhus och samtidigt bevara den arkitektoniska karaktären i de båda klimatzonerna. Standardhuset med ett plan och pulpettak är endast möjligt att anpassa till passivhus i klimatzon III med bevarad arkitektonisk karaktär. Livscykelkostnadsanalysen visar med hjälp av nuvärdesmetoden att det är ekonomiskt fördelaktigt att investera i passivhus som ett koncept för en kalkylperiod på 50 år. Den boendekvalitet som främst förändras är bostadens ljusinsläpp och för passivhuset i ett plan är skillnaden av ljusinsläpp markant i klimatzon I. Studiens slutsats är att konceptet passivhus är en metod av husbyggnation som främjar den hållarbara utvecklingen i förenklad form. Resultaten är framförallt positiva för klimatzon III men om byggnaden har låg formfaktor kan konceptet fungera bra även i kallare klimat som återfinns i klimatzon I. / The climate changes increases as the population increases. The negative environmental impact is mostly based on the use of raw materials and energy consumption in the production of various products. According to Energimyndigheten (2015), the building sector is the cause of about 40 % of Sweden's total energy use. In order to reduce the energy use goals have been created at both national and international levels. The goals are intended to create a greater understanding of a more energy efficient society for all actors within the construction industry. In addition to create a sustainable development of the building sector one needs to also take in account the social and economic aspects. This master thesis examined whether two specific standard houses from a small house producer can be adapted to passive houses with a preserved architectural character. The purpose of the study is partly to investigate whether the concept of passive houses can serve as a sustainable concept of building single family houses. The concept of sustainable development has been simplified. The ecological aspect is represented by the energy calculations and possible actions that the standard houses need to achieve in order to meet the requirements for passive houses. The economic aspect is represented by a life cycle cost analysis using the Net Present Value method and the Simple Payback method. The social aspect is represented by an evaluation of changes in living qualities as the standard houses develops to passive houses. The study also presents an alternative design of a passive house with the purpose of improving the accommodation qualities. The standard houses belong to a small-house-producer, Intressanta hus, who has their main market in Västerås. The houses is represented by a 147m2 villa with one floor and a pulpit roof and a 151m2 villa with two floors and a pitched roof. Due to Intressanta hus geographic location, the typical climate for Västerås has been used in the energy calculations. To add another dimension, opportunities for developing the standard houses to passive houses have also been investigated for the typical climate in Kiruna. Therefore Västerås represents climate zone III and Kiruna represents climate zone I. The results revealed that it is possible to adapt the standard house with two floors and a pitched roof to a passive house while preserving the architectural character in both climate zones. The standard house with one floor and a pulpit roof is only possible to adjust to a passive house in climate zone III with a preserved architectural character. The life cycle cost analysis using the Net Present Value showed that it is an economical advantage to invest in a passive house in a period of 50 years. The accommodation quality that changes the most is the incident light in the houses and for the passive house with one floor the difference of light is remarkably high in climate zone I.
|
Page generated in 0.0729 seconds