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Este trabajo aborda la caracterización de permeabilidad al aire de la envolvente de los edificios residenciales en España. Para ello, se propone una metodología con la que se ha estudiado una muestra representativa de casos, que ha generado una base de datos. El grado de permeabilidad al aire, evaluado mediante ensayos de presurización por medio de ventilador, muestra el comportamiento dispar de los edificios y un considerable potencial de ahorro energético. También se ha estudiado la relación entre diferentes características constructivas y el grado de permeabilidad al aire, y se han identificado los focos de filtración más comunes. El diseño inadecuado de las soluciones constructivas, así como la descuidada ejecución de los encuentros entre diferentes elementos, se han señalado como las principales causas que impiden envolventes más herméticas, y, en consecuencia, suponen los principales retos a afrontar en el futuro., Departamento de Construcciones Arquitectónicas, Ingeniería del Terreno y Mecánica de los Medios Continuos y Teoría de Estructuras, Doctorado en Arquitectura

Infiltration has a considerable impact on both, energy efficiency and occupant comfort in buildings. Due to the complexity of the analysis of this phenomenon in buildings, the verification methods are very important for its diagnostics and evaluation. In this paper, the matter of infiltration in buildings is being considered referring to both, calculation models and methods, as well as through current standards and regulations in the EU and Serbia. Different valorization methods are presented and analyzed regarding their characteristics, applicability, and complexity. Finally, preliminary infiltration measurements with a pressurization test, conducted on selected buildings of Belgrade housing stock are presented and compared with values defined by the current regulations in Serbia. Results pointed out current problems and the need for improvements regarding the treatment of infiltration in local regulations and practice. Инфилтрација има значајан утицај у разматрању питања како енергетске ефикасности тако и комфора у објектима. Због сложености анализе овог феномена, методе верификације показале су се као веома важне приликом дијагностиковања и евалуације инфилтрације. У овом раду се питање инфилтрације разматра у односу на моделе и методе прорачуна, као и тренутне стандарде и прописе у ЕУ и Србији. Разматране су различите методе верификације кроз анализу и поређење њихових карактеристика, применљивост и сложеност. Представљена су и прелиминарна мерења инфилтрације одабраних објеката у склопу стамбеног фонда Београда тестом притиска удувавањем која су упоређена са вредностима дефинисаним важећим прописима у Србији. Резултати су указали на тренутне проблеме и потребу унапређења третмана инфилтрације у локалним прописима и пракси.

Ventilation in built environments is essential to guarantee a good indoor air quality and a reduced probability of infection related to virus transmission. Measuring ventilation-related parameters is not easy and currently two methods can be adopted: pressurization and tracer gas decay. The pressurization test measures the airtightness of the building, whereas the tracer gas decay test measures the actual (site- and climate-specific) air exchange rate. Finding a relationship amongst the results provided by the two tests would be very useful in view of an exhaustive characterization of the building ventilation, but it still remains an open challenge for the scientific literature. The present paper aims at investigating the criticalities in correlating the two methods; thus, an experimental campaign was performed in a multi-room dwelling performing both air permeability and air exchange rate measurements in the entire dwelling and in parts of it. A detailed uncertainty budget of the two methods was also carried out in order to perform metrological compatibility analyses. The results of the campaign highlighted that the actual air exchange rates of the dwelling present a huge variability (from 100, with an exponential decrease as the wind velocity increases. Thus, adopting constant conversion factors could significantly overestimate the actual ventilation of the building.

The study is focused on the evaluation of air permeability and ventilation rate in Italian classrooms. Measurements were performed in 16 naturally ventilated classrooms located in Cassino, Central Italy. Classrooms’ airtightness was evaluated through the fan pressurization method. Air exchange rates where both estimated from the blower door results and measured using a CO2 decay test method. The effect of the periodic manual airing of the classrooms (through window and door opening) was also investigated performing CO2 and particle number concentration measurements during the school time.

Producción Científica, The primary objective of this paper is to present the use of a steady model that is able to qualify and quantify available natural ventilation flows applied to the energy retrofitting of urban residential districts. In terms of air quality, natural ventilation presents more efficient solutions compared to active systems. This method combines numeric simulations, through the utilization of Ansys Fluent R15.0® and Engineering Equation Solver EES®, with on-site pressurization tests. Testing consists of the application of the seasonal pressure gradient on the building’s envelope and the calculation of the ventilation flows in three climatic representative conditions (summer, winter, and annual average). Through the implementation of this methodology to existing buildings it is possible to evaluate the influence of the built environment, as well as key parameters (relative height of the dwelling, number of vertical ventilation ducts, and airtightness of windows) of available natural ventilation., CITyFiED project, which has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration activities under the Grant Agreement number 609129

Natural ventilation is the dominating ventilation process in ancient buildings like churches, and also in most domestic buildings in Sweden and in the rest of the world. These buildings are naturally ventilated via air infiltration and airing. Air infiltration is the airflow through adventitious leakages in the building envelope, while airing is the intentional air exchange through large openings like windows and doors. Airing can in turn be performed either as single-sided (one opening) or as cross flow ventilation (two or more openings located on different walls). The total air exchange affects heating energy and indoor air quality. In churches, deposition of airborne particles causes gradual soiling of indoor surfaces, including paintings and other pieces of art. Significant amounts of particles are emitted from visitors and from candles, incense, etc. Temporary airing is likely to reduce this problem, and it can also be used to adjust the indoor temperature. The present study investigates mechanisms and prediction models regarding air infiltration and open-door airing by means of field measurements, experiments in wind tunnel and computer modelling. In natural ventilation, both air infiltration and airing share the same driving forces, i.e. wind and buoyancy (indoor-outdoor temperature differences). Both forces turn out to be difficult to predict, especially wind induced flows and the combination of buoyancy and wind. In the first part of the present study, two of the most established models for predicting air infiltration rate in buildings were evaluated against measurements in three historical stone churches in Sweden. A correction factor of 0.8 is introduced to adjust one of the studied models (which yielded better predictions) for fitting the large single zones like churches. Based on field investigation and IR-thermography inspections, a detailed numerical model was developed for prediction of air infiltration, where input data included assessed level of the neutral pressure level (NPL). The model functionality was validated against measurements in one of the case studies, indicating reasonable prediction capability. It is suggested that this model is further developed by including a more systematic calibration system for more building types and with different weather conditions. Regarding airing, both single-sided and cross flow rates through the porches of various church buildings were measured with tracer gas method, as well as through direct measurements of the air velocity in a porch opening. Measurement results were compared with predictions attained from four previously developed models for single‑sided ventilation. Models that include terms for wind turbulence were found to yield somewhat better predictions. According to the performed measurements, the magnitude of one hour single-sided open-door airing in a church typically yields around 50% air exchange, indicating that this is a workable ventilation method, also for such large building volumes. A practical kind of diagram to facilitate estimation of suitable airing period is presented. The ability of the IDA Indoor Climate and Energy (IDA-ICE) computer program to predict airing rates was examined by comparing with field measurements in a church. The programs’ predictions of single-sided airflows through an open door of the church were of the same magnitude as the measured ones; however, the effect of wind direction was not well captured by the program, indicating a development potential. Finally, wind driven air flows through porch type openings of a church model were studied in a wind tunnel, where the airing rates were measured by tracer gas. At single-sided airing, a higher flow rate was observed at higher wind turbulence and when the opening was on the windward side of the building, in agreement with field measurements. Further, the airing rate was on the order of 15 times higher at cross flow than at single-sided airing. Realization of cross flow thus seems highly recommendable for enhanced airing. Calibration constants for a simple equation for wind driven flow through porches are presented. The measurements also indicate that advection through turbulence is a more important airing mechanism than pumping. The present work adds knowledge particularly to the issues of air infiltration and airing through doors, in large single zones. The results can be applicable also to other kinds of large single-zone buildings, like industry halls, atriums and sports halls. Naturlig ventilation är den dominerande ventilationsprocessen i äldre byggnader såsom kyrkor, och även i de flesta småhus i Sverige och övriga delar av världen. Luftinfiltration och vädring utgör viktiga komponenter i naturlig ventilation, där luftinfiltration är luftflöde genom oavsiktliga läckage i byggnadsskalet, medan vädring är avsiktligt luftutbyte genom stora öppningar såsom fönster och dörrar/portar. Vädring kan i sin tur ske ensidigt (genom en öppning) eller som tvärdrag (genom två eller flera öppningar belägna på olika ytterväggar). Det totala luftutbytet påverkar värmeförluster och inomhusluftens kvalité. I kyrkor orsakar avsättning av luftpartiklar en gradvis nedsmutsning av invändiga ytor, inklusive väggmålningar och andra konstföremål. Betydande mängder partiklar avges från besökare, tända ljus, rökelse, o.d. Tillfällig vädring kan minska detta problem, men även användas för att justera innetemperaturen. Föreliggande studie analyserar mekanismer och predikteringsmodeller gällande luftinfiltration och dörrvädring genom fältmätningar, vindtunnelförsök och datorsimuleringar. Luftinfiltration och vädring har samma drivkrafter, d.v.s. vind och termik (inne‑ute temperaturskillnader). Båda dessa drivkrafter är svåra att predicera, särskilt vindinducerade flöden och kombinationen av termik och vind. Två av de mest etablerade modellerna för luftinfiltrationsprediktering i byggnader har utvärderats via mätningar i tre kulturhistoriska stenkyrkor i Sverige. En korrigeringsfaktor av 0,8 föreslås för bättre prediktion av den ena modellen (som gav bäst resultat) gällande höga en-zonsbyggnader såsom kyrkor. En detaljerad numerisk modell är utvecklad för luftinfiltrationsprediktering, där indata baseras på fältundersökningar, inkl. IR-termografering och uppmätt av neutrala tryckplanet (NPL). Modellens funktionalitet har validerats via mätningar i en av fallstudierna och pekar på tämligen god prediktionsprestanda. Vidare utveckling av modellen föreslås, inkl. ett mer systematiskt kalibreringssystem, för olika typer av byggnader och väderförhållanden. Gällande vädring mättes både ensidigt flöde och tvärdrag genom portar i olika kyrkobyggnader med hjälp av spårgas samt direkta lufthastighetsmätningar i portöppning. Mätresultaten jämfördes med erhållna prediktioner från fyra tidigare utvecklade modeller för ensidig ventilation. De modeller som tog hänsyn till vindturbulens gav något bättre resultat. Enligt utförda mätningar medför en timmes ensidig portvädring i en kyrka cirka 50 % luftutbyte, vilket indikerar att detta är en tillämpbar ventilationsmetod, även för så pass stora byggnadsvolymer. Ett särskilt vädringsdiagram presenteras, som syftar till att underlätta uppskattning av erforderlig vädringsperiod. Vidare studerades predikteringsprestanda hos IDA Indoor Climate and Energy (IDA-ICE) simuleringsprogram avseende vädring, där simuleringsdata jämfördes med fältmätningar i en kyrka. Programmets prediktion av ensidigt luftflöde genom en öppen kyrkport var av samma storlekordning som det uppmäta; dock klarade programmet inte av att hantera inverkan av vindriktning så väl, vilket pekar på en utvecklingspotential. Avslutningsvis undersöktes vinddrivet flöde igenom portöppningar i en kyrkmodell i vindtunnel, där luftomsättningen mättes med hjälp av spårgasmetoden. Vid ensidig vädring observerades högre flöde vid högre vindturbulens och när öppningen var på vindsidan av byggnaden, i överensstämmelse med fältmätningarna. Dessutom var vädringsflödet vid tvärdrag i storleksordningen 15 högre än det vid ensidig vädring. Det verkar alltså som att man kan öka vädringstakten avsevärt om man kan åstadkomma tvärdrag. Kalibreringskonstanter presenteras också för en enkel ekvation för vinddrivet flöde genom portar. Vindtunnelstudien indikerar vidare att advektion genom turbulens är en viktigare vädringsmekanism än pumpning. Föreliggande arbete bidrar med kunskap speciellt kring luftinfiltration och vädring genom portar i höga en-zonsbyggnader. Resultaten kan även vara tillämpliga på andra typer av höga en-zonsbyggnader såsom industrihallar, atrier/ljusgårdar och idrottshallar. Church project

In recent years, building retrofitting has grown in importance, due to the need to improve construction and energy conditions, but omitting those relating to ventilation. This is due to the difficulty to estimate the available natural ventilation and the limited solutions derived from DB-HS3. This work aims to present a methodology, through numeric simulations and climate data, able to solve the seasonal pressure gradient in the building’ envelope and, once known the airtightness with on-site pressurization tests, the calculation of the ventilation flows in three representative conditions (summer, winter an annual average). To fulfill the HS3 requirement is advisable to use the performance-based nature of CTE, which allows other alternative solutions to the DB. But it is necessary to introduce changes in the regulations to allow the proposed solution of an individual ventilation system with variable flow or Controlled Cross Ventilation., En los últimos años, la rehabilitación de edificios ha experimentado un gran impulso, haciendo hincapié en aspectos constructivos y energéticos, pero omitiendo los relativos a la ventilación. Esto se debe a la dificultad de conocer la ventilación natural disponible y en las escasas soluciones derivadas del DB-HS3. Este trabajo pretende exponer una metodología para, a partir de simulaciones numéricas y datos climáticos, obtener el gradiente estacional de presiones en los cerramientos y, conocida su permeabilidad mediante ensayos de presurización in situ, obtener los caudales disponibles en tres períodos del año (verano, invierno y media anual). Para el cumplimiento de la exigencia HS3 es recomendable acudir al carácter prestacional del CTE, que admite otras soluciones alternativas al Documento Básico, pero es necesario introducir una serie de cambios para la solución propuesta de proyectar un sistema individual de ventilación con caudal variable o Ventilación Cruzada Controlada.

In recent years, building retrofitting has grown in importance, due to the need to improve construction and energy conditions, but omitting those relating to ventilation. This is due to the difficulty to estimate the available natural ventilation and the limited solutions derived from DB-HS3. This work aims to present a methodology, through numeric simulations and climate data, able to solve the seasonal pressure gradient in the building’ envelope and, once known the airtightness with on-site pressurization tests, the calculation of the ventilation flows in three representative conditions (summer, winter an annual average). To fulfill the HS3 requirement is advisable to use the performance-based nature of CTE, which allows other alternative solutions to the DB. But it is necessary to introduce changes in the regulations to allow the proposed solution of an individual ventilation system with variable flow or Controlled Cross Ventilation. En los últimos años, la rehabilitación de edificios ha experimentado un gran impulso, haciendo hincapié en aspectos constructivos y energéticos, pero omitiendo los relativos a la ventilación. Esto se debe a la dificultad de conocer la ventilación natural disponible y en las escasas soluciones derivadas del DB-HS3. Este trabajo pretende exponer una metodología para, a partir de simulaciones numéricas y datos climáticos, obtener el gradiente estacional de presiones en los cerramientos y, conocida su permeabilidad mediante ensayos de presurización in situ, obtener los caudales disponibles en tres períodos del año (verano, invierno y media anual). Para el cumplimiento de la exigencia HS3 es recomendable acudir al carácter prestacional del CTE, que admite otras soluciones alternativas al Documento Básico, pero es necesario introducir una serie de cambios para la solución propuesta de proyectar un sistema individual de ventilación con caudal variable o Ventilación Cruzada Controlada.