Development of a weight factor method for sustainability decisions in building renovation. Case study using Renobuild

Energy efficiency investments have become strategically important for the European Union. In particular, energy efficient renovation and investment in the existing building stock have become major challenges. Renovation of a building should involve a holistic and integrated design process, which considers all aspects of sustainability. The aim of this work is to suggest a mathematical model that weighs economic, social and ecological aspects into a measure that supports housing owners/decision makers to find the optimal renovation alternative from their perspective, taking factors such as budget, energy consumption, etc. into consideration. Multi-criteria decision-making (MCDM) concerns structuring and solving multiple-criteria decision problems. MCDM has become popular in energy planning as it enables the decision maker to pay attention to all the criteria available and make the appropriate decision as per the priority of the criteria. In this study, the concept is introduced based on economic, social and ecological aspects assessed during a renovation project. A pedagogical example illustrates the suggested numerical system for comparing different renovation alternatives. The suggested method will facilitate decision-making processes in renovation projects and will allow decision makers to choose the best renovation alternatives that are in line with their business ideas and principles.publishedVersio

Review on District Cooling and Its Application in Energy Systems

This chapter investigates the implementation of district cooling systems by exploring several research studies reported in the literature. The topics addressed include typologies and design parameters, benefits and limitations, applications of the system, and the technology readiness level. District cooling systems are generally regarded as cost-efficient and environmentally friendly solutions. One might think that district cooling is only a solution for areas with a very warm climate. However, based on the reported results of the surveyed studies, the number of operating district cooling systems has increased over the years, with the Scandinavian countries taking the lead in this market within European countries. Implementation of these systems concluded reduction in primary energy and electricity use, they also proved to be an environmentally efficient way

Viewpoints on Environmental Assessment of Building Certification Method - Miljöbyggnad

Production, management, use, and end-of-life of buildings has a large impact on climate change. Therefore, environmental targets are set to lower the greenhouse gas (GHG) emissions from the building sector. To reach these targets building regulation and voluntary environmental assessment methods (EAMs) that evaluate and certify the building’s environmental impact are put forward as tools to push the building sector towards lower GHG emissions. In Sweden, building design is governed by building regulations and the dominant EAM is ‘Miljöbyggnad’ (MB) (“Environmental building”). Today, more than 1900 buildings have been certified by MB and it has influenced the building and property sector. In this chapter the potential impact MB and the linked Swedish building regulations have on building performance, energy use and GHG emissions, will be reviewed and discussed. The analysis investigates several of the MB’s indicators, evaluate to what degree EAMs can influence the design of the building and the energy system to lower the energy use and GHG emissions based on material choices. The analysis presents important aspects that may influence the design of the building and its energy system and what challenges and possibilities the indicators, criteria and regulations can have on buildings and climate change. In addition, some modification and suggestion for improvements are presented

Resilient cooling strategies – A critical review and qualitative assessment

The global effects of climate change will increase the frequency and intensity of extreme events such as heatwaves and power outages, which have consequences for buildings and their cooling systems. Buildings and their cooling systems should be designed and operated to be resilient under such events to protect occupants from potentially dangerous indoor thermal conditions. This study performed a critical review on the state-of-the-art of cooling strategies, with special attention to their performance under heatwaves and power outages. We proposed a definition of resilient cooling and described four criteria for resilience—absorptive capacity, adaptive capacity, restorative capacity, and recovery speed —and used them to qualitatively evaluate the resilience of each strategy. The literature review and qualitative analyses show that to attain resilient cooling, the four resilience criteria should be considered in the design phase of a building or during the planning of retrofits. The building and relevant cooling system characteristics should be considered simultaneously to withstand extreme events. A combination of strategies with different resilience capacities, such as a passive envelope strategy coupled with a low-energy space-cooling solution, may be needed to obtain resilient cooling. Finally, a further direction for a quantitative assessment approach has been pointed out

The ORC method

The ORC Method (Optimised RC-networks) provides a means ofmodelling one- or multidimensional heat transfer in buildingcomponents, in this context within building simulationenvironments. The methodology is shown, primarily applied toheat transfer in multilayer building components. For multilayerbuilding components, the analytical thermal performance isknown, given layer thickness and material properties. The aimof the ORC Method is to optimise the values of the thermalresistances and heat capacities of an RC-model such as to givemodel performance a good agreement with the analyticalperformance, for a wide range of frequencies. The optimisationprocedure is made in the frequency domain, where the over-alldeviation between model and analytical frequency response, interms of admittance and dynamic transmittance, is minimised. Itis shown that ORC's are effective in terms of accuracy andcomputational time in comparison to finite difference modelswhen used in building simulations, in this case with IDA/ICE.An ORC configuration of five mass nodes has been found to modelbuilding components in Nordic countries well, within theapplication of thermal comfort and energy requirementsimulations. Simple RC-networks, such as the surface heat capacity andthe simple R-C-configuration are not appropriate for detailedbuilding simulation. However, these can be used as basis fordefining the effective heat capacity of a building component.An approximate method is suggested on how to determine theeffective heat capacity without the use of complex numbers.This entity can be calculated on basis of layer thickness andmaterial properties with the help of two time constants. Theapproximate method can give inaccuracies corresponding to20%. In-situ measurements have been carried out in anexperimental building with the purpose of establishing theeffective heat capacity of external building components thatare subjected to normal thermal conditions. The auxiliary wallmethod was practised and the building was subjected toexcitation with radiators. In a comparison, there werediscrepancies between analytical and measured effective heatcapacities. It was found that high-frequency discrepancies wereto a large extent caused by the heat flux sensors.Low-frequency discrepancies are explained by the fact that theexterior climate contained other frequencies than those assumedin the interior climate. Key words: Building component, building simulation, heattransfer, thermal performance, frequency response, RC-network,finite difference model.NR 2014080

Sustainability of world heritage : who inherits the ownership of decorated farmhouses of Hälsingland?

This chapter discusses sustainability of Sweden’s most recent World Heritage (WH) site, the Decorated Farmhouses of Hälsingland. A general overview presents what WH is, why it is special and why it should be preserved for future generations. The views of WH farm owners on managing a WH site and how they feel about the task have been assessed. WH must be preserved for future generations and it is necessary for the farms to interact sustainably with their local communities. Most WH farms are privately owned and have been within the same family for centuries. Will this continue in the future or are there problems with succession

Development of a Numerical Air Infiltration Model Based On Pressurization Test Applied On a Church

Pressurization (blower door) test is a well-established standardized method, performed in order to quantify the total leakage in a building envelope. However, blower door results are not adequate to use when air leakage through the building envelope during natural conditions (non-pressurized) is to be estimated. A common assumption made when estimating air leakage during natural conditions, is that air leakage paths are evenly distributed in the areas of the building envelope. This assumption gives quite poor calculation results since different leakage configurations are often situated unevenly in the envelope. In order to improve the correspondence between Blower door and air leakage model results, more information on the types and locations of the leakage paths are required as input to simulation models.  This paper investigates if additional information from visual inspection and IR-thermography observations at site can increase the precision when simulating air change rates due to air leakage in natural conditions.  A numerical model is developed in this study by allocating leakage in various parts of the building envelope. The leakage allocation is based on visual inspection and IR-thermography observations at the site during the blower door test. This procedure is tested in the case study of a large single zone church. Blower door, neutral pressure level measurement and leakage allocation results are used as input in the numerical model. Model results are compared with tracer gas measurements and result accuracy is compared with results from the Lawrence Berkeley Laboratory model (LBL) and the Alberta Air Infiltration Model (AIM-2) for the same church. Church projec

Development and validation of energy signature method - Case study on a multi-family building in Sweden before and after deep renovation

Building energy use constitutes a large part of total energy use, both in the European Union and Sweden. Due to this energy use, and the resulting emissions, several goals for energy efficiency and emissions have been set. In Sweden, a large portion of multi-family buildings were built between 1960 and 1980, which have major energy savings potential. The purpose of this paper is further development and validation of previously introduced energy signature method and its inherent parameters. The method was applied on a multi-family building where thermal energy data supplied by the district heating company was available before and after deep renovation. Using IDA ICE, a building energy simulation (BES) software model was created of the building, to aid in validation of the energy signature method. The paper highlighted the accuracy of the proposed energy signature (PES) method and a sensitivity analysis on the inherent parameters have been performed. The results showed new ways of treatment of the thermal energy data and revealed how more information can be extracted from this data. (C) 2020 The Authors. Published by Elsevier B.V.Funding Agencies|Gavle Energi AB (GEAB), Gavle, Sweden</p

Field test of dehumidifiers for avoiding condensation in unheated historical wooden houses

The UNESCO world heritage “Decorated Farmhouses of Hälsingland” represent a well-preserved Swedish regional timber building tradition from the 18th and 19th centuries, featuring wall paintings of high cultural and artistic value. The houses have remained unheated and naturally ventilated over centuries, and have relatively leaky building envelopes. Recent indoor climate measurements and observations, however, have identified occasional condensation on indoor surfaces during unfavourable weather changes in wintertime. Such condensation poses a risk of degrading the wall paintings and other valuable objects, although low winter temperatures prevent mold growth. To mitigate condensation risk, sorption dehumidifiers – working also at temperatures below 0 °C – were installed in one of the UNESCO farmhouses during a winter season. The dehumidifiers were programmed to limit the indoor air relative humidity (RH) at maximum 80 %, and their dried air was distributed to all rooms via a flexible ductwork. Additionally, climate loggers and passive tracer gas technique were employed to measure temperature, RH, and air change rate in all rooms. By comparing with measured indoor climate in other similar farmhouses in the region, the results indicate that the dehumidifiers chiefly managed to limit RH at 80 %, thus preventing condensation in all rooms, despite a relatively high mean air change rate of around 0.8 ACH. However, locally and temporarily, enhanced RH peaks occurred, possibly due to unfavourable transient wind and/or stack conditions. The study also provides some practical installation guidance

Simulation of Ventilation Rates and Heat Losses during Airing in Large Single Zone Buildings in Cold Climates

Airing can be a solution to introduce extra ventilation in large single zone buildings, especially where there are large aggregations of people such as churches or atriums. In naturally ventilated domestic and ancient buildings, opening of a window or door can introduce extra fresh air and remove particles and other contaminants emitted from people and other sources such as lit candles in churches. However, the energy use might be an issue in cold climates, where airing might lead to waste of heated air, at the same time as indoor air temperatures can be uncomfortably low. In the present study, the energy loss and ventilation rate due to airing in a large single zone (church) building is investigated via IDA-ICE simulation on annual basis in cold weather conditions. The results can be used in order to prepare airing guidelines for large single zone buildings such as atriums, churches, industry halls and large sport halls. According to the results, one-hour of airing in the studied church building resulted in 40-50 % of exchanged room air and, if practiced once a week, an increase of around 1 % in heating energy.Forthcomming March 2019</p