Türkiye'deki geleneksel ahşap çerçeve sistem konut yapılarında dış duvarların ısıl ve nemsel performansının değerlendirilmesi
Hygrothermal performance assessment of exterior walls of traditional timber framed houses in Türkiye
Yazar: SEDA NUR ALKAN
Danışman: DOÇ. DR. FATİH YAZICIOĞLU
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Mimarlık Ana Bilim Dalı / Yapı Bilim Dalı
Derece: Doktora, 2023
Konu: Mimarlık = Architecture ; Mühendislik Bilimleri = Engineering Sciences

Özet:
Dış duvarlar, iç ve dış çevreyi birbirinden ayıran bir sınır oluşturarak hem atmosferik 
koşullara hem de iç çevredeki kullanıcı ve kullanım kaynaklı oluşan iç ortam hava 
koşullarının etkisi altında bir arayüz oluştururlar. Hem iç hem de dış ortam koşullarına 
maruz kalan dış duvarların iç ortamda istenilen kullanıcı konfor koşullarını 
sağlayabilmesi öncelikli konulardan biridir. Bu bağlamda değerlendirildiğinde, dış 
duvarın ısıl ve nemsel performansı kritik öneme sahiptir. Isıl ve nemsel performans; 
ışıma, iletim ve taşıma yolu ile ısı akışını; buhar difüzyonu ve sıvı taşınımı ile buhar 
akışını; doğal, dışsal ve mekanik kuvvetlerle oluşan hava akışını incelemektedir. 
Türkiye, tarihsel süreç içinde pek çok farklı kültüre ev sahipliği yapmıştır. Bunun bir 
yansıması olarak, zengin bir konut kültürüne sahiptir. Bu kültürün önemli bir parçası 
olan geleneksel ahşap çerçeve konut yapıları, ısıl ve nemsel performansın kapsadığı 
konular ve önemi dikkate alındığında öncelikli incelenmesi gereken başlıklardan 
biridir. Mimari, tarihi, kültürel ve sosyal değere sahip olan bu yapıların değerlerinin 
korunarak gelecek nesillere aktarılması noktasında, dış duvarlarının ısıl ve nemsel 
performansının iyi olması; bu yapıların enerji etkinliklerinin arttırılmasına katkı 
sağlaması, ısı ve nem etkisiyle oluşabilecek ve yapının yaşam ömrünü olumsuz 
etkileyebilecek sonuçları engellemesine katkı sunabilir. Bu husustan yola çıkılarak, 
mevcut durum tespitlerinin yapılması ve gerekli olan durumlarda iyileştirme 
önerilerinin değerlendirilmesi aşamalarında ısıl ve nemsel performans araştırmaları 
halihazırda devam eden ve/veya yapılacak olan koruma/restorasyon/ rekonstrüksiyon
çalışmalarına veri sağlaması bakımından önemlidir. 
Bu çalışmanın amacı; Türkiye'deki geleneksel ahşap çerçeve sistem konut yapılarının 
dış duvar sistemlerinin sayısal ve deneysel yöntemlerle ısıl ve nemsel performansının 
değerlendirilip koruma/restorasyon/rekonstrüksiyon çalışmalarında performans 
iyileştirme için yapı fiziksel koşulların gözetilerek gerekli yaklaşımların ve müdahale 
stratejilerinin geliştirilmesidir. Bu amaç doğrultusunda, Türkiye'deki geleneksel ahşap 
çerçeve konut yapılarının dış duvar sistemlerini temsil edebilecek ve en çok örneği 
görülen 4 farklı duvar tipi belirlenmiştir. Belirlenen 4 tip duvar için 2 farklı model, her 
model içinse 2 farklı duvar katmanlaşması tespit edilmiştir. Belirlenen duvar 
modellerinin ısıl ve nemsel performans değerlendirmesinin sayısal değerlendirmesi 
DELPHIN yazılımı ile, deneysel değerlendirmesi ise TSE Yapı Malzemeleri Yangın 
ve Akustik Laboratuvarı Müdürlüğü Laboratuvarı'nda bulunan mahfazalı sıcak oda 
cihazı ile gerçekleştirilmiştir. Bu noktada, ısıl ve nemsel performans değerlendirmesi 
için belirlenen tipler üzerinden tasarlanacak duvar modelleri için mahfazalı sıcak oda 
ölçüleri olan 150 cm x 150 cm deney alanı sınır olarak kabul edilmiş ve duvar 
modelleri bu ölçü doğrultusunda tasarlanmıştır. Çalışmanın ilk aşamasında, duvar 
katmanlaşmalarına göre belirlenen malzemelerin DELPHIN yazılımına işlenmek 
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üzere ısıl iletkenlik değeri Düzce Üniversitesi Bilimsel ve Teknolojik Araştırmalar 
Uygulama ve Araştırma Merkezi'nde ölçtürülmüş, gerekli diğer fiziksel özelliklerinin 
belirlenmesine yönelik deneyler İTÜ Mimarlık Fakültesi Yapı Malzemesi 
Laboratuvarı'nda gerçekleştirilmiştir. İkinci aşamada, TSE Yapı Malzemeleri Yangın 
ve Akustik Laboratuvarı Müdürlüğü Laboratuvarı'nda, seçilen 4 duvar modeli inşa 
edilmiş ve mahfazalı sıcak oda deneyleri yapılmıştır. Bu çalışmadan elde edilen 
sıcaklık ve U değerleri ile ilgili veriler, bu duvar modellerinin aynı koşullar altında 
yapılan DELPHIN simülasyon sonuçları ile karşılaştırılmıştır. Sonraki aşamada ise, 
tasarlanan tüm duvar modellerinin DELPHIN yazılımı ile her örneğin bulunduğu ilin 
iklim verileriyle simülasyonu yapılarak; sıcaklık, bağıl nem ve ısıl iletkenlik değerleri 
incelenmiştir. 
Bu çalışmada, Türkiye'deki geleneksel ahşap çerçeve dış duvar sistemleri incelenerek 
bu tipleri temsil edebilecek örneklerin ısıl ve nemsel performansı sayısal ve deneysel 
yöntemlerle değerlendirilmiştir. Elde edilen bilgiler doğrultusunda, DELPHIN 
yazılımının mevcut durum tespiti ve eğer gerekli ise iyileştirme önerilerinin 
değerlendirilmesi noktasında bir araç olarak kullanılmasının önemli bir veri 
sağlayacağı öngörülmüştür. Bununla birlikte, kapsamlı çalışmalar için deneysel 
yöntemlere başvurulmasının önemli olduğu görülmektedir. Çalışma, geleneksel ahşap 
çerçeve sistem konutların koruma/restorasyon/rekonstrüksiyon çalışmalarında 
kullanılmak üzere ön değerlendirme ve tespit noktasında çalışmalara kılavuz 
olabilecek veri sağlamıştır.

Abstract:
Türkiye has a unique range of traditional architecture that consists of significant 
examples of wooden material and methods of construction varied according to 
geographical, social, economic, and cultural characteristics. They are hybrid 
constructions whereby an infilled timber-framed system is erected on the masonry 
walls. Most constructed traditional timber-framed houses in Türkiye may be grouped 
into four types according to infill materials as follows: (1) timber-framed adobe infill, 
(2) timber-framed brick infill, (3) timber-framed stone infill, and (4) veneered timberframed (unfilled timber-framed). The construction is composed of rectangular studs of 
pinewood/beech tree/oak/ash tree, and infill material of adobe, brick, and stone. 
Wooden diagonals are constructed to cope with the dynamic loads particularly 
earthquake and wind for stability and durability in the long term. Due to the physical 
characteristics of wooden materials, they are affected directly by temperature and 
moisture. Hence, hygrothermal performance plays significant role for traditional 
timber houses regarding historical, architectural, cultural, and social values, durability 
and energy efficiency. Traditional timber-framed houses, which are significant 
architectural examples in Türkiye, are one of the crucial topics in terms of 
hygrothermal performance. In order to transfer them to the next generations, 
hygrothermally well performed walls may contribute to energy efficiency and protect 
negative effects of moisture-based problems by conserving their values. Based on 
these issues, hygrothermal performance analysis of these buildings are important to 
provide data for ongoing and/or will be planned
conservation/restoration/reconstruction projects in terms of determination of current 
situation and/or improvement strategies. Hygrothermal performance can be 
comprehensively defined as the evaluation of the energy, humidity, and air balance of 
the building elements. In other words, hygrothermal performance are explained as the 
movement of heat, air, and moisture.
The exterior walls act as an interface between the interior and exterior environment. 
The exterior walls both expose to atmospheric conditions and indoor weather 
conditions. The fundamental factors to supply the climatic comfort conditions in the 
indoor environment are the heat and moisture permeability, heat storage and air 
permeability of the exterior wall. Considering these situations, hygrothermal 
performance of exterior wall, which is focused on the air, heat, and temperature effects 
on wall, is crucial to investigate the behavior of wall. 
The aim of this research is to evaluate the hygrothermal performances of traditional 
timber-framed houses' exterior walls in Türkiye to create a base case scenario of 
hygrothermal behavior as a datum for conservation and restoration projects. The 
method of this research is conducted on three main parts: (1) a comprehensive 
literature review, (2) experimental study and (3) numerical study. The first phase of 
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the research is started with a comprehensive literature review. The purpose of this 
phase is to contribute to create theoretical data about the hygrothermal performance 
analysis and the wall specimens' design. Literature review generates the theoretical 
knowledge about the hygrothermal performance analysis and inputs about wall 
assembly design criteria. Based on the results of literature review; the system, and 
layers of external wall of traditional timber framed houses in Türkiye were examined. 
The ratio of wooden and infill materials of the selected façade examples in the 
literature were calculated to design the wall assembly as case study. Among the 
hygrothermal performance assessments, numerical method, as the most advantageous 
in terms of time and budget, is mostly preferred. The experimental method, on the 
other hand, is the second widely used method. Although it is more advantageous in 
terms of time compared to the in-situ measurement method, it is more costly than the 
numerical method. In the literature, generally the experimental method is applied 
together with the numerical method to evaluate the accuracy and reliability of the 
research data by comparing the results.
Accordingly, hygrothermal performance analysis of the traditional timber framed 
system exterior wall was examined by numerical and experimental method within the 
context of this research. DELPHIN was applied for the numerical analysis of the wall 
assembly. DELPHIN is one of the most applied simulation tools for hygrothermal 
performance analysis. DELPHIN is created by the IBK Institut für Bauklimatik 
(Building Climate Control, Technische Universität Dresden, Faculty of Architecture). 
DELPHIN has capability to make analysis about the heat, moisture, air, and salt 
transport in building materials. It is a user-friendly simulation tool that can be applied 
for examination of hygrothermal performance, moisture-based problem, insulation 
proposals, thermal performance improvement etc. The guarded hot box was applied 
for experimental analysis. The experimental study has two phases: (1) material 
properties analysis and (2) guarded hot box analysis. Material properties analysis was 
conducted on Istanbul Technical University Faculty of Architecture Construction 
Materials Lab. The laboratory analysis about bulk density, water uptake coefficient, 
open porosity, vapor diffusion resistance factor (μ value) and hygroscopic sorption 
(RH= 80%) values of the materials were realized in Istanbul Technical University 
Faculty of Architecture Construction Materials Lab. Thermal conductivity of the 
materials was measured by Düzce Üniversitesi Bilimsel ve Teknolojik Araştırmalar 
Uygulama ve Araştırma Merkezi. The tested materials were randomly selected. Even 
hygroscopic sorption values (RH= 80%) of the materials were found by the analysis, 
these values cannot be changed in DELPHIN. Therefore, the selected materials were
determined depending on the closer hygroscopic sorption value (RH= 80%) found by 
the material properties analysis. After finding the material properties by the laboratory 
analysis, the similar materials of DELPHIN library were edited according to these 
values. Other material properties seen on DELPHIN library screen were kept as it is 
defined.
Within the scope of the experimental study, the major phase is to design wall specimen. 
To investigate the system and the layers of the traditional timber framed houses' 
exterior wall in Türkiye, a comprehensive literature review was conducted. Specific 
exterior wall examples were selected to calculate the system configuration and the 
ratio of wooden and infill material or unfilled parts. Afterwards, depending on this data 
the wall specimens were designed as 150 cm x 150 cm which is the dimensions of 
guarded hot box in the Turkish Standards Institution Construction Materials Fire and 
Acoustic Laboratory. 
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Guarded hot box analysis was realized in the Turkish Standards Institution 
Construction Materials Fire and Acoustic Laboratory. In the hot box phase, the sample 
to be tested was placed in the designated area between the hot and cold chambers with 
known ambient temperatures, and it is carried out while powering the part on the hot 
chamber side at steady-state air and surface temperatures. After finishing the wall 
assembly construction, the wall assembly was waited to get dry naturally. Then the 
wall assembly was put in drying oven for 7 days till its weight got stabilized. 
Afterwards, the wall assembly was kept under the room conditions for 1 day. 
Following, thermocouples were installed on the walls and the wall assembly was 
installed to guarded hot box between two climatic chambers. The warm climatic 
chamber was arranged as Twarm: 20°C, and the cold climatic chamber was arranged as 
Tcold: 0°C. The climatic chambers were automatically controlled to keep constant 
temperature value. The relative humidity of the chambers was set as 50%. The 
durations of the tests were changed depending on the wall assembly. The outputs of 
the laboratory measurements were applied for the validation of DELPHIN simulation 
tool for the hygrothermal performance analysis of the wall assembly. The 
measurement points for simulation were determined as same with hot box apparatus 
measurement points. For simulation process in DELPHIN, a dialog for automatic 
discretization should be created. In this dialog, the construction was discretized as 
minimum element size 1 mm, maximum element size 50 mm and stretch factor 1.6. 
The dialog generated a grid for calculation. Boundary conditions were arranged as 
same with guarded hot box analysis for comparison of the data. DELPHIN simulations 
were realized under the steady state conditions to compare guarded hot box analysis 
with DELPHIN hygrothermal modelling. Therefore, boundary conditions were 
determined same as with guarded hot box analysis conditions which is advised in TS 
EN ISO 8990. Indoor environment was arranged as Tindoor: 20°C, RHindoor: 50%, 
outdoor environment was arranged as Toutdoor: 0°C, RHoutdoor: 50%. The initial 
temperature was set at 20 ⁰C and the relative humidity at 50%. The orientation of the 
wall assembly was arranged to 0 Deg for North and the inclination to 0 Deg for Section 
A-A and Section E-E, 90 Deg for Section B-B, Section C-C, Section D-D and Section 
E-E. Because of the elimination of complex effects, it was supposed that the wall 
assembly is facing northwards. The durations of the simulations were arranged same 
as the duration of the guarded hot box measurements. 
The evaluation includes the comparison of guarded hot box analysis and DELPHIN 
hygrothermal modelling. The temperature and U-value of these analysis were 
compared for validation of the data. U value is calculated according to the national 
standard of thermal insulation requirements for buildings in Türkiye, TS825. Firstly, 
temperature values of guarded hot box analysis and DELPHIN numerical modelling 
were examined. Total of 18 measurements points locating symmetrically inside and 
outside of the wall assembly supplied data. Then, U-value of the walls measured by 
the guarded hot box apparatus and thermal conductivity values as outputs of DELPHIN 
simulations were analyzed. Here, depending on the thermal conductivity values of the 
walls, U-values were calculated. 
The results shows that experimental study has a critical to accuracy of numerical 
modelling for hygrothermal performance evaluation. Particularly, material variations 
create unexpected impacts on the wall layers. The intersection and interaction points 
of different materials are needed to deeply analysis by experimental and numerical 
methods. For temperature values, mostly, the simulated values have good agreements 
with measured values on the wooden parts of the wall assembly. Contrary, the 
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differences between the measured and simulated values of infill and unfilled parts of 
the wall assembly are subjected to discuss. Moreover, faulty workmanship and its 
effects on the differences between the simulated values and measured values need to 
be examined. 
In the second step, hygrothermal performances of the wall specimens over 2 years 
(01.01.2014 - 01.01.2016) were investigated by DELPHIN simulation tool. The 
evaluation of data is based on the analysis of temperature, relative humidity, and Uvalue. The findings indicate that when factors such as construction details, materials, 
and climatic conditions are varied, there may be humidity-based problems in the 
selected examples. In that case, intersection points of materials, layers, and their 
relationships should be re-evaluated to improve the hygrothermal performances of the 
selected walls for conservation and restoration projects.
Within the scope of this study, material properties were assigned for the simulations 
by editing determined values of the selected materials in DELPHIN library. The 
simulation data was applied to compare guarded hot box analysis and numerical 
modelling. In that case, the material properties play crucial roles as being same with 
the constructed wall specimen and the simulated wall assembly for certain data. It 
gives opportunity to examine the results regarding accuracy and validation. It creates 
a data for analysis of hygrothermal performance of the wall assembly with same inputs 
by two different method application. For the further studies, this consideration is 
required to be applied for different types of wall assemblies to clarify the impacts of 
material variations, interactions, and intersections of different materials. 
The results of both guarded hot box analysis and DELPHIN modelling show that U 
value of the wall assembly cannot achieved the recommended value in TS825. 
Considering this result, it is critical to improve the U value of the wall assembly by 
conserving its historical, architectural, cultural, and social values. Because of it 
requires a comprehensive study, insulation proposals for the improvement are not 
discussed in this research. Merely, it may be important to specify the beneficials of 
natural based insulation materials for these types of improvements. Besides, to 
preserve the originality and uniqueness of the outer surface the walls, it is crucial to 
consider insulation material application to the inside of the walls. However, moisturebased problems in the long-term require to be analyzed in detail.
This research contributes to make discussions about the hygrothermal performances 
of traditional timber framed exterior walls in Türkiye and also applicability of 
simulation tools with experimental methods. The expected outcome of this research is 
to generate a significant source to be applied for the 
conservation/restoration/reconstruction projects of traditional timber framed houses as 
a tool. Especially, with this work it is expected to create a comprehensive data for 
moisture-based problem analysis. Additionally, field measurements of specific 
buildings may be applied for comparison of experimental and numerical studies for 
the further studies.