Monthly utilisation factors for building energy calculations

2016 ◽  
Vol 38 (3) ◽  
pp. 318-326 ◽  
Author(s):  
Roger Hitchin
Keyword(s):  
Linear Model ◽  
Energy Use ◽  
Potential Temperature ◽  
Energy Performance ◽  
Space Heating ◽  
Base Temperature ◽  
Outdoor Temperature ◽  
Energy Performance Of Buildings ◽  
Heating And Cooling ◽  
The Mean

Monthly utilisation factors are the basis of many procedures for calculation of monthly heating or cooling requirements for buildings, notably in the procedure described in standard ISO 13790:2008 ‘Energy performance of buildings – Calculation of energy use for space heating and cooling’, which is widely used for the implementation of the Energy Performance of Buildings Directive in Europe. The procedures used to determine the values of the factors are invariably empirical rather than being derived from first principles, with the principal parameter being the ratio between monthly mean heat gains and monthly mean heat losses for the space in question. This article shows that this ratio is inherently insufficient to define the values and illustrates how months with similar values of the ratio can have different utilisation factors. It also shows that, if daily heating requirement is proportional to outdoor temperature, the key building parameter needed to determine the utilisation factor is the familiar base temperature. The base temperature can be expressed in terms of the monthly gain: loss ratio and the mean indoor and external temperatures: the day-to-day frequency distributions of outdoor temperature is also important. Finally, the article demonstrates that, for many situations, the ISO 13790 procedure and a linear model with residuals produce similar estimates of monthly heating requirement. However, this is not true towards the upper end of its observed range. In this situation, the linear model produces lower values for utilisation factors and correspondingly higher heating (and cooling) requirements. This effect is most marked when the mean indoor and outdoor temperatures are close or the space is well-insulated (causing a given heat gain to represent a higher potential temperature difference). Practical application: Monthly utilisation factors are the basis of many procedures for the calculation of monthly heating or cooling requirements for buildings, notably in the procedure described in standard ISO 13790:2008 ‘Energy performance of buildings – Calculation of energy use for space heating and cooling’, which is widely used for the implementation of the Energy Performance of Buildings Directive in Europe. This article shows that an alternative approach based on the concept of energy signatures, although producing very similar results in many situations, is a more robust and extendable basis for monthly heating and cooling energy demand calculations.

Energy performance of buildings in Poland on the basis of different climatic data

2016 ◽  
Vol 26 (4) ◽  
pp. 551-566 ◽  
Author(s):  
Magdalena Grudzińska ◽  
Ewa Jakusik
Keyword(s):  
Energy Demand ◽  
Indoor Environment ◽  
Energy Use ◽  
Residential Building ◽  
Energy Performance ◽  
Climatic Data ◽  
Energy Performance Of Buildings ◽  
Energy Needs ◽  
Source Data ◽  
The Mean

Typical Meteorological Years (TMY) were prepared in Poland due to the introduction of obligatory energy certification for buildings. They are based on source data collected by the Institute of Meteorology and Water Management from 1971 to 2000. Predictions indicate that until the end of the 21st century, the air temperature will increase. Therefore, the characteristics obtained with the use of TMY may differ from the energy demand of buildings used nowadays. This article compares energy demand calculated with the use of TMY and subsequent climatic data from 2001 to 2012, for three different locations in Poland. The analyses were performed with the use of the dynamic simulation computer program, for typical living quarters in a multifamily residential building with different construction and window orientation. Results obtained with the use of TMY and subsequent climatic data show that the typical years can be used for the evaluation of heating demand. However, cooling demand calculated with the use of TMY was significantly lower in comparison with the mean cooling demand for the years 2001–2012. This may distort the energy needs and indoor environment conditions in summer, and cause discomfort or unnecessary energy use in presently occupied dwellings.

scholarly journals Evaluation of Urban-Scale Building Energy-Use Models and Tools—Application for the City of Fribourg, Switzerland

2021 ◽  
Vol 13 (4) ◽  
pp. 1595
Author(s):  
Valeria Todeschi ◽  
Roberto Boghetti ◽  
Jérôme H. Kämpf ◽  
Guglielmina Mutani
Keyword(s):  
Machine Learning ◽  
Energy Use ◽  
Residential Buildings ◽  
Building Energy ◽  
Energy Performance ◽  
Space Heating ◽  
Engineering Model ◽  
Building Energy Use ◽  
The Impact ◽  
The City

Building energy-use models and tools can simulate and represent the distribution of energy consumption of buildings located in an urban area. The aim of these models is to simulate the energy performance of buildings at multiple temporal and spatial scales, taking into account both the building shape and the surrounding urban context. This paper investigates existing models by simulating the hourly space heating consumption of residential buildings in an urban environment. Existing bottom-up urban-energy models were applied to the city of Fribourg in order to evaluate the accuracy and flexibility of energy simulations. Two common energy-use models—a machine learning model and a GIS-based engineering model—were compared and evaluated against anonymized monitoring data. The study shows that the simulations were quite precise with an annual mean absolute percentage error of 12.8 and 19.3% for the machine learning and the GIS-based engineering model, respectively, on residential buildings built in different periods of construction. Moreover, a sensitivity analysis using the Morris method was carried out on the GIS-based engineering model in order to assess the impact of input variables on space heating consumption and to identify possible optimization opportunities of the existing model.

Energy Saving Policies for Housing Based on Wrong Assumptions?

2014 ◽  
Vol 39 (2) ◽  
pp. 78-83
Author(s):  
Henk Visscher ◽  
Dasa Majcen ◽  
Laure Itard
Keyword(s):  
Energy Saving ◽  
Energy Demand ◽  
Energy Use ◽  
Housing Stock ◽  
Energy Performance ◽  
Research Projects ◽  
Building Stock ◽  
Energy Saving Potential ◽  
Energy Performance Of Buildings ◽  
New Buildings

The energy saving potential of the building stock is large and considered to be the most cost efficient to contribute to the CO2 reduction ambitions. Severe governmental policies steering on reducing the energy use seem essential to stimulate and enforce the improvement of the energy performance of buildings with a focus on reducing the heating and cooling energy demand. In Europe the Energy Performance of Buildings Directive is a driving force for member states to develop and strengthen energy performance regulations for new buildings and energy certificates for the building stock. The goals are to build net zero energy new buildings in 2020 and to reach a neutral energy situation in the whole stock by 2050. More and more research projects deliver insight that the expected impact of stricter regulations for newly built houses is limited and the actual effects of energy savings through housing renovations stay behind the expectations. Theoretical energy use calculated on base of the design standard for new houses and assessment standards for Energy Performance Certificates of existing dwellings differ largely from the measured actual energy use. The paper uses the findings of some Post Occupancy Evaluation research projects. Is the energy saving potential of the housing stock smaller than expected and should we therefore change the policies?

scholarly journals A Complementary Approach to Traditional Energy Balances for Assessing Energy Efficiency Measures in Final Uses: The Case of Space Heating and Cooling in Argentina

2020 ◽  
Vol 12 (16) ◽  
pp. 6563
Author(s):  
Roque G Stagnitta ◽  
Matteo V Rocco ◽  
Emanuela Colombo
Keyword(s):  
Energy Consumption ◽  
Energy Use ◽  
Primary Energy ◽  
Embodied Energy ◽  
Space Heating ◽  
Output Analysis ◽  
Final Energy ◽  
Heating And Cooling ◽  
Energy Balances ◽  
The Impact

Energy balances have been historically conceived based on a supply-side perspective, providing neither detailed information about energy conversion into useful services nor the effects that may be induced by the application of policies in other sectors to energy consumption. This article proposes an approach to a thorough assessment of the impact of efficiency policies on final energy uses, focusing on residential space heating and cooling, and capable of: (1) quantifying final useful services provided and (2) accounting for the global impact of efficiency policies on final energy use, taking advantage of Input–Output analysis. This approach is applied in five cities of Argentina. Firstly, the quantity of energy service provided (i.e., level of thermal comfort) for each city is evaluated and compared with the defined target. It is found out that heating comfort is guaranteed approximately as established, whereas in the cooling case the provision is twice the established level. Secondly, primary energy consumption of heating and cooling services is evaluated before and after different efficiency improvement policies. The results show that the major primary energy saving (52%) is obtained from the upgrading appliances scenario and reflect the importance of accounting for embodied energy in goods and services involved in interventions.

scholarly journals Full-scale Studies of Improving Energy Performance by Renovating Historic Swedish Timber Buildings with Hemp-lime

2019 ◽  
Vol 9 (12) ◽  
pp. 2484 ◽  
Author(s):  
Paulien Strandberg-de Bruijn ◽  
Anna Donarelli ◽  
Kristin Balksten
Keyword(s):  
Energy Saving ◽  
Material Properties ◽  
Energy Use ◽  
Building Design ◽  
Energy Performance ◽  
Full Scale ◽  
Space Heating ◽  
Original Material ◽  
Insulation Material ◽  
Thermal Transmittance

With an increased focus on reducing greenhouse gas emissions, energy saving is of great importance in all sectors of society. EU directives set targets for member states to reduce energy use in buildings. Energy saving in historic buildings requires special measures, balancing energy-saving renovations against the preservation of heritage values. Traditional constructions are open to vapor diffusion and generally work differently from modern constructions. Modern materials in traditional constructions sometimes damages the original material as they are usually diffusion-tight. The aim of this study was to investigate whether hemp-lime could be used as an insulation material to improve the energy efficiency of historic timber building envelopes with a rendered façade in Sweden. The objective was to determine the actual energy savings for space heating. An additional objective was to determine the actual thermal transmittance and to study thermal buffering through in-situ measurements in a full-scale wall renovated with hemp-lime. Two full-scale wall sections were constructed at the Energy and Building Design laboratory at Lund University: A traditional post-and-plank wall with a lime render (80 mm), and a post-and-plank wall with a hemp-lime render (90 mm). Energy use for space heating was monitored continuously over a period of one year. The wall with a hemp-lime render required 33% less energy for space heating than the traditional post-and-plank wall with a lime render. This was accomplished without changing the framework, appearance or material in the render and without drastically changing the hygric properties of the façade. From the gathered data, the thermal transmittance (U-values) for both walls was calculated using two different methods, one based on material properties and the other based on energy use data. For both walls, thermal transmittance based on actual energy use data during the heating period was lower than what was expected from their material properties. This indicates that more material properties than thermal conductivity and material thickness need to be taken into account when performing energy use calculations. With hemp-lime, a renovation can be accomplished without damaging the timber structure and wooden slats, and it can be done with local traditional materials and building methods with no difference in appearance to a traditional lime render. This allows for heritage values to be preserved, while also allowing the building to comply with modern standards and with increased thermal comfort and reduced energy use.

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