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Nair, Gireesh
Publications (10 of 39) Show all publications
Nair, G., Olofsson, T., Nordlund, A. & Hudson, C. (2019). Comparative evaluation of city dwellers’ perspectives on household energy use based on housing tenure: survey results from Northern Sweden (1ed.). In: Johansson, Dennis, Bagge, Hans, Wahlström, Åsa (Ed.), Cold Climate HVAC 2018: Sustainable Buildings in Cold Climates. Paper presented at 9th International Cold Climate Conference, Sustainable new and renovated buildings in cold climates, Kiruna – Sweden 12-15, March 2018 (pp. 791-802). Paper presented at 9th International Cold Climate Conference, Sustainable new and renovated buildings in cold climates, Kiruna – Sweden 12-15, March 2018. Switzerland: Springer Publishing Company
Open this publication in new window or tab >>Comparative evaluation of city dwellers’ perspectives on household energy use based on housing tenure: survey results from Northern Sweden
2019 (English)In: Cold Climate HVAC 2018: Sustainable Buildings in Cold Climates / [ed] Johansson, Dennis, Bagge, Hans, Wahlström, Åsa, Switzerland: Springer Publishing Company, 2019, 1, p. 791-802Chapter in book (Refereed)
Place, publisher, year, edition, pages
Switzerland: Springer Publishing Company, 2019 Edition: 1
Series
Springer Proceedings in Energy, ISSN 2352-2534
National Category
Civil Engineering
Identifiers
urn:nbn:se:umu:diva-152727 (URN)10.1007/978-3-030-00662-4 (DOI)978-3-030-00661-7 (ISBN)
Conference
9th International Cold Climate Conference, Sustainable new and renovated buildings in cold climates, Kiruna – Sweden 12-15, March 2018
Available from: 2018-10-21 Created: 2018-10-21 Last updated: 2018-12-16
Nordlund, A., Nair, G., Hudson, C. & Olofsson, T. (2018). Att utveckla en stadsdel på ett hållbart sätt: en fråga om energi, transporter och människor. Umeå: Transportforskningsenheten, Umeå Universitet
Open this publication in new window or tab >>Att utveckla en stadsdel på ett hållbart sätt: en fråga om energi, transporter och människor
2018 (Swedish)Report (Other academic)
Place, publisher, year, edition, pages
Umeå: Transportforskningsenheten, Umeå Universitet, 2018. p. 59
Series
TRUM, ISSN 1403-6924 ; 2018:1
Keywords
Hållbar stadsutveckling, Universitetsstaden, Attityder och beteende, Energianvändning, Resbeteende, Åtgärder, Samhällsplanering
National Category
Social Sciences Interdisciplinary
Identifiers
urn:nbn:se:umu:diva-147957 (URN)
Projects
Umeå – En testbädd för hållbar stadsutveckling
Funder
Swedish Energy Agency
Available from: 2018-05-23 Created: 2018-05-23 Last updated: 2018-06-19Bibliographically approved
Azizi, S., Nair, G. & Olofsson, T. (2018). Comparative Study of Influential Factors on Implementation of Energy Efficiency Measures in Single-Family Houses in Cold Climate. In: : . Paper presented at 2018 ACEEE Summer Study in Energy Efficiency in Buildings.
Open this publication in new window or tab >>Comparative Study of Influential Factors on Implementation of Energy Efficiency Measures in Single-Family Houses in Cold Climate
2018 (English)Conference paper, Published paper (Refereed)
Abstract [en]

A combination of factors, which include occupants and building related aspects, could motivate homeowners to implement energy renovation (ER). This study applies a comparative approach to assess perspectives of single-family homeowners towards different energy efficiency measures (EEMs). The aim is to unveil the factors that are effective on the residents’ attitude and decision making to implement an EEM or a set of EEMs. The analysis is based on a questionnaire survey conducted during spring 2017 among1550 owners of single-family houses in seven municipalities in northern Sweden. Approximately, 35% of respondents expressed their interest to install energy efficient household appliances and solar photovoltaic (PV) systems. The analysis suggests significant relations between the homeowners’ interest to implement thermal envelope measures and the quality of the house such as age and indoor environmental problems such as cold surfaces. The group of respondents, who reported their heating cost to be high, are more likely to be interested in implementing thermal envelope measures than other measures such as HVAC. Several socio-economic factors are found to be significantly related with homeowners’ interest to implement EEMs.

Keywords
Energy efficient renovation
National Category
Energy Engineering
Identifiers
urn:nbn:se:umu:diva-151878 (URN)
Conference
2018 ACEEE Summer Study in Energy Efficiency in Buildings
Funder
European Regional Development Fund (ERDF)
Available from: 2018-09-14 Created: 2018-09-14 Last updated: 2018-09-14
Allard, I., Olofsson, T. & Nair, G. (2018). Energy evaluation of residential buildings: Performance gap analysis incorporating uncertainties in the evaluation methods. Building Simulation, 11(4), 725-737
Open this publication in new window or tab >>Energy evaluation of residential buildings: Performance gap analysis incorporating uncertainties in the evaluation methods
2018 (English)In: Building Simulation, ISSN 1996-3599, E-ISSN 1996-8744, Vol. 11, no 4, p. 725-737Article in journal (Refereed) Published
Abstract [en]

Calculation and measurement-based energy performance evaluations of the same building often provide different results. This difference is referred as "the performance gap". However, a large performance gap may not necessarily mean that there are flaws in the building or deviations from the intended design. The causes for the performance gap can be analysed by calibrating the simulation model to measured data. In this paper, an approach is introduced for verifying compliance with energy performance criteria of residential buildings. The approach is based on a performance gap analysis that takes the uncertainties in the energy evaluation methods into consideration. The scope is to verify building energy performance through simulation and analysis of measured data, identifying any performance gap due to deviations from the intended design or flaws in the finished building based on performance gap analysis. In the approach, a simulation model is calibrated to match the heat loss coefficient of the building envelope [kWh/K] instead of the measured energy. The introduced approach is illustrated using a single-family residential building. The heat loss coefficient was found useful towards identifying any deviations from the intended design or flaws in the finished building. The case study indicated that the method uncertainty was important to consider in the performance gap analysis and that the proposed approach is applicable even when the performance gap appears to be non-existing.

Place, publisher, year, edition, pages
Tsinghua University Press, 2018
Keywords
performance gap, energy signature, calibration, simulation, design criteria
National Category
Energy Engineering
Identifiers
urn:nbn:se:umu:diva-150666 (URN)10.1007/s12273-018-0439-7 (DOI)000435421700008 ()2-s2.0-85048691979 (Scopus ID)
Note

Originally included in thesis in manuscript form with title A methodology to investigate the building energy performance gap

Available from: 2018-08-20 Created: 2018-08-20 Last updated: 2018-11-13Bibliographically approved
Olofsson, T., Nair, G. & Azizi, S. (2018). Enkät om renovering och energieffektivisering [Review]. Energi & Miljö (1)
Open this publication in new window or tab >>Enkät om renovering och energieffektivisering
2018 (Swedish)In: Energi & Miljö, no 1Article, book review (Other (popular science, discussion, etc.)) Published
Place, publisher, year, edition, pages
Stockholm: , 2018
National Category
Energy Systems
Identifiers
urn:nbn:se:umu:diva-145549 (URN)
Available from: 2018-03-09 Created: 2018-03-09 Last updated: 2018-09-14
Nair, G., Azizi, S. & Olofsson, T. (2017). A management perspective on energy efficient renovations in Swedish multi-family buildings. Energy Procedia, 132, 994-999
Open this publication in new window or tab >>A management perspective on energy efficient renovations in Swedish multi-family buildings
2017 (English)In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 132, p. 994-999Article in journal (Refereed) Published
Abstract [en]

Sweden has around 2.5 million dwellings in multi-family buildings, which constitute about 55% of the total dwelling units. The multi-family building ownership in Sweden can be categorized into municipal, private and co-operative ownership. Approximately 40% of apartments in multi-family buildings belong to municipal housing companies, while the rest is equally shared by private companies and co-operative housing associations. These organizations have different priorities, limitations and concerns related to energy renovations. Accordingly, in this sector the decisions to invest in energy efficiency improvement depends to a large extent on the type of ownership.

In this study we analyzed the perspectives of different types of building ownership on energy efficient renovation. The analysis is based on detailed interviews of 4 senior managers representing the multi-family buildings under different ownership categories. Along with this we also interviewed a municipality energy adviser. All the interviewees are based in in North Sweden. The drivers to facilitate the rate of adoption of energy renovation in such buildings are discussed.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Energy renovations, barriers, multi-family buildings, decisions, Sweden
National Category
Energy Systems
Identifiers
urn:nbn:se:umu:diva-133613 (URN)10.1016/j.egypro.2017.09.699 (DOI)000426435500166 ()2-s2.0-85033386266 (Scopus ID)
Available from: 2017-04-14 Created: 2017-04-14 Last updated: 2018-06-11Bibliographically approved
Nair, G., Allard, I., Åstrand, A. & Olofsson, T. (2017). Building professionals' views on energy efficiency compliance requirements. In: Geving S., Time B. (Ed.), 11th Nordic Symposium on Building Physics, NSB 2017: . Paper presented at 11th Nordic Symposium on Building Physics (NSB), JUN 11-14, 2017, Trondheim, NORWAY (pp. 988-993). Elsevier, 132
Open this publication in new window or tab >>Building professionals' views on energy efficiency compliance requirements
2017 (English)In: 11th Nordic Symposium on Building Physics, NSB 2017 / [ed] Geving S., Time B., Elsevier, 2017, Vol. 132, p. 988-993Conference paper, Published paper (Refereed)
Abstract [en]

In Sweden, the national building code (BBR) stipulates the specific energy use as an indicator to verify whether a newbuilding is complying with its design-phase energy performance values. However, previous studies have shown that there may belarge differences between the calculated specific energy and the actual monitored energy use. The differences are attributed tovarious reasons including the actual energy behaviour of the occupants as compared to the standard values used in thesimulations. This may lead to disputes between the client and the contractor on the responsibility of meeting the energyrequirements.In this study an adapted version of Delphi methodology was used to understand the building professionals’ view on variousindicators used to verify building energy performance. The study showed that professionals are concerned with the use of specificenergy as an indicator in the building procurement process as they do not have control over the occupants’ energy behaviour.Majority of the professionals expressed a large confidence in the average U-value of the building, component U-values and thespecific heat loss figure by the Swedish center for zero-energy buildings as indicators of building energy performance.

Place, publisher, year, edition, pages
Elsevier, 2017
Series
Energy Procedia, ISSN 1876-6102
Keywords
energy performance indicators, energy efficency, u-value, buildings, Sweden
National Category
Energy Systems
Identifiers
urn:nbn:se:umu:diva-133612 (URN)10.1016/j.egypro.2017.09.697 (DOI)000426435500165 ()2-s2.0-85033397222 (Scopus ID)
Conference
11th Nordic Symposium on Building Physics (NSB), JUN 11-14, 2017, Trondheim, NORWAY
Available from: 2017-04-14 Created: 2017-04-14 Last updated: 2018-06-11Bibliographically approved
Allard, I., Olofsson, T. & Nair, G. (2017). Energy performance indicators in the Swedish building procurement process. Sustainability, 9(10), Article ID 1877.
Open this publication in new window or tab >>Energy performance indicators in the Swedish building procurement process
2017 (English)In: Sustainability, ISSN 2071-1050, E-ISSN 2071-1050, Vol. 9, no 10, article id 1877Article in journal (Refereed) Published
Abstract [en]

In Sweden, all new buildings need to comply with the National Board of Housing, Building and Planning’s requirement on specific purchased energy (kWh/m2). Accordingly, this indicator is often used to set design criteria in the building procurement process. However, when energy use is measured in finished buildings, the measurements often deviate significantly from the design calculations. The measured specific purchased energy does not necessarily reflect the responsibility of the building contractor, as it is influenced by the building operation, user behavior and climate. Therefore, Swedish building practitioners may prefer other indicators for setting design criteria in the building procurement process. The aim of this study was twofold: (i) to understand the Swedish building practitioners’ perspectives and opinions on seven building energy performance indicators (envelope air leakage, U-values for different building parts, average U-value, specific heat loss, heat loss coefficient, specific net energy, and specific purchased energy); and (ii) to understand the consequences for the energy performance of multi-family buildings of using the studied indicators to set criteria in the procurement process. The study involved a Delphi approach and simulations of a multi-family case study building. The studied indicators were discussed in terms of how they may meet the needs of the building practitioners when used to set building energy performance criteria in the procurement process.

Place, publisher, year, edition, pages
MDPI, 2017
Keywords
design criteria, energy performance, specific energy, simulation, procurement process, indicators
National Category
Energy Systems
Identifiers
urn:nbn:se:umu:diva-140862 (URN)10.3390/su9101877 (DOI)000414896200207 ()
Available from: 2017-10-20 Created: 2017-10-20 Last updated: 2018-06-09Bibliographically approved
Yang, B., Olofsson, T., Nair, G. & Kabanshi, A. (2017). Outdoor thermal comfort under subarctic climate of north Sweden: a pilot study in Umeå. Sustainable cities and society, 28, 387-397
Open this publication in new window or tab >>Outdoor thermal comfort under subarctic climate of north Sweden: a pilot study in Umeå
2017 (English)In: Sustainable cities and society, ISSN 2210-6707, Vol. 28, p. 387-397Article in journal (Refereed) Published
Abstract [en]

Outdoor microclimate is important to determine the quality of outdoor spaces. Swedish people cherish summer period and prefer more outdoor activities in summer because of long winter with harsh outdoor environments. People in urban areas use parks for recreation and outdoor activities frequently in summer. Under subarctic climate, limited studies have been performed to explore the effect of microclimate environments on usage of outdoor spaces such as parks. The study explored the relationship of microclimate environments, park use and human behavioral patterns in urban area of Umeå, Sweden, which is under subarctic climate. Observations of naturally occurring behavior were recorded. Structured interviews, based on specially designed questionnaires, were performed during July to August in 2015. Measurements of objective parameters for microclimate environments, including air dry bulb temperature, relative humidity, wind speed, solar radiation and globe temperature, were performed. Human subjective responses from the questionnaire survey were compared with objectively measured results. 49% of local persons still prefer higher solar radiation even under "slightly warm" Thermal Sensation Vote (TSV), which reflects their high expectation to solar radiation. Local persons in Umeå, who expose themselves to a wider climate, are more adapted to subarctic climate than non-local persons. Practical implications: The pilot study demonstrated that wind attenuation together with strong sunshine can improve Thermal Sensation Vote (TSV), which could be realized by specially designed hump terrain for attenuating wind without shading effects. The results will be used for optimizing design of urban outdoor environments such as parks under subarctic or arctic climate.

Keywords
Thermal comfort, Thermal sensation vote, Subarctic climate, Outdoor environment
National Category
Architectural Engineering Building Technologies
Identifiers
urn:nbn:se:umu:diva-127566 (URN)10.1016/j.scs.2016.10.011 (DOI)000389322700036 ()
Available from: 2016-11-15 Created: 2016-11-15 Last updated: 2018-06-09Bibliographically approved
Soleimani-Mohseni, M., Nair, G. & Hasselrot, R. (2016). Energy simulation for a high-rise building using IDA ICE: investigations in different climates. Building Simulation, 9(6), 629-640
Open this publication in new window or tab >>Energy simulation for a high-rise building using IDA ICE: investigations in different climates
2016 (English)In: Building Simulation, ISSN 1996-3599, E-ISSN 1996-8744, Vol. 9, no 6, p. 629-640Article in journal (Refereed) Published
Abstract [en]

In this paper a model of a high-rise building is constructed in the simulation program IDA ICE. The model is based on an IFC-model of a demonstration building constructed in Ljubljana, Slovenia, as part of an EU-project, EE-high-rise. The model's energy performance was simulated for four cities: Umeå (Scandinavia), Ljubljana (Central Europe), Sibenik (Mediterranean) and Dubai (The Persian Gulf). Furthermore, the climate envelope of the building was modified with the aim to improve the model's energy performance in each of the regions. The results were evaluated according to the energy requirements of passive house standard by the German Passive House Institute. The analysis suggests that the reference building model, which itself incorporates several energy efficient components, was unable to meet the German passive house standard in none of the four cities (Umeå, Ljubljana, Sibenik and Dubai) studied. By providing a combination of energy saving measures, such as modifications of thermal resistance of building envelope, the building may be able to meet the passive house standard in Ljubljana. The analysis concludes that the reduction in window area results in reduction of both heating and cooling demand. Increase in the thickness of the insulation and the thermal resistance of windows reduces the space heating demand for Umeå, Ljubljana and Sibenik (not applied for Dubai) while increasing the cooling demand for these cities. Increased airtightness has marginal effect on heating and cooling demand for all investigated cities. Reduced thermal resistance of windows will decrease cooling demand for Ljubljana, Sibenik and Dubai (not applied for Umeå). Reduced insulation thickness (not applied for Umeå) will decrease cooling demand for Ljubljana and Sibenik but not for Dubai. Reducing the insulation thickness may often result in reduced cooling demand for moderately warm countries since the average outdoor temperature could be lower than the indoor temperature during part of the cooling season. In those situations a reduced insulation thickness can cause heat flow from the relatively hot inside to the colder outside. However, for hot climates like in Dubai where outdoor temperature is higher than the indoor temperature for most of the year, reducing the insulation thickness will increase the cooling demand. This result suggests that the insulation thickness must be chosen and optimized based on heating and cooling demand, internal heat gain, and outdoor climate

Place, publisher, year, edition, pages
Tsinghua University Press, 2016
Keywords
energy performance of buildings, simulation, high-rise buildings, IDA ICE, passive house, building envelop, climate zones
National Category
Energy Engineering Construction Management Building Technologies
Identifiers
urn:nbn:se:umu:diva-124409 (URN)10.1007/s12273-016-0300-9 (DOI)000383847600002 ()
Available from: 2016-08-10 Created: 2016-08-10 Last updated: 2018-06-07Bibliographically approved
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