Abstract
Southern European areas are traditionally considered to have a benign climate and therefore most homes often do not have controlled ventilation systems or air conditioning. Our society faces challenging situations with global pandemics and health emergencies, while housing provides the basic elements of refuge and activity. A profound transformation of social and labor dynamics is underway, increasing at-home presence, hence the capital importance of improving building envelopes to reduce energy demand and to increase occupant comfort levels in order to ensure their protective function. Air leakage is one of the key factors both in indoor air quality and energy demand. This study aims to explore the sensitivity of energy demand to airtightness. A representative set of multifamily buildings, built in the last 20 years in Seville, is analyzed. The results show that air permeability has a significant effect on energy demand in the sample studied. Although impact is greater in severe climates, it needs to be considered in temperate climates, especially when more time is spent at home.
TopIntroduction
Spain is the European country with the second-highest number of deaths in winter (Healy, 2017), and equally high figures in the warm season. These figures are directly related to the environmental conditions in housing, where occupants spend much of their day. The current housing stock, most of which is over 50 years old, presents a significant degree of obsolescence with a performance capacity that is limited in many cases. In general, the oldest group of housing units has poor construction standards, especially in low-income or social housing. It is often found that the indoor environmental conditions of the dwellings are far from what are usually regarded as comfortable or healthy, even in the climatic zones of regions usually considered mild or moderate climates (Domínguez-Amarillo, Sendra, Fernández-Agüera, & Escandón, 2017; Domínguez-Amarillo, Sendra, & Oteiza San José, 2016). The combination of building envelopes of limited capacity, thermal systems that are not very suitable - inefficient in many cases - and situations of energy poverty or high energy costs are usually responsible for this situation (Domínguez-Amarillo, Fernández-Agüera, Peacock, & Acosta, 2019; Sendra, Domínguez-Amarillo, Bustamante Rojas, & Leon, 2013). In this context the uncontrolled air exchange between the outside and the inside of the buildings, characterized by envelope airtightness, is one of the key variables in residential energy consumption and indoor-ambient performance, as are comfort and IAQ.
The main aim of this work is to provide a methodological proposal for the development of predictive models of energy consumption in dwellings in relation to airtightness, presenting a model of the case of the city of Seville in southern Spain.
To do so, using calculation engine EnergyPlus this study proposes to simulate the energy behavior of a representative sample of multifamily housing buildings in one climate area, assessing the repercussion of infiltrations and the influence of urban context in the operational conditions of the housing on energy demand. Based on these energy consumption simulations, airtightness tests and the study of their morphological and typological characteristics, a model was established to predict the energy demand of the dwellings classified by typological and morphological characteristics.
Key Terms in this Chapter
Building Envelope: All of the elements of the outer shell that maintain a dry, heated, or cooled indoor environment and facilitate its climate control.
Natural Ventilation: Intentional passive flow of outdoor air into a building through planned openings (such as louvers, doors, and windows).
Air Infiltration: Unintentional flow of air from outdoors to indoors through leaks (unplanned openings) in a building envelope.
Airtightness: Uncontrolled inward and outward leakage of outdoor air through cracks, interstices, or other unintentional openings of a building, caused by pressure effects of the wind and/or stack effect
Ventilation: Intentional introduction of outdoor air into a space that is mainly used to control indoor air quality.
Predictive Modeling: The process of using known results to create, process, and validate a model that can be used to forecast future outcomes.
Air Exchange Rate: Number of interior volume air changes that occur per hour, and has units of 1/h.
Mechanical Ventilation: A building ventilation system that uses powered fans or blowers to provide fresh air to rooms when the natural forces of air pressure and gravity are not enough to circulate air through a building.