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In order to improve energy performance of buildings, insulation materials (such as mineral glass and rock wools, or fossil fuel-based plastic foams) are being used in increasing quantities, which may lead to potential problem with materials depletions and landfill disposal. One sustainable solution suggested is the use of bio-based, biodegradable materials. A number of attempts have been made to develop biomaterials, such as sheep wood, hemcrete or recycled papers. In this paper, a novel type of bio insulation materials – mycelium is examined. The aim is to produce mycelium materials that could be used as insulations. The bio-based material was required to have properties that matched existing alternatives, such as expanded polystyrene, in terms of physical and mechanical characteristics but with an enhanced level of biodegradability. The testing data showed mycelium bricks exhibited good thermal performance. Future work is planned to improve growing process and thermal performance of the mycelium bricks.
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IOP Conference Series: Earth and Environmental Science
Growing and testing mycelium bricks as building insulation materials
To cite this article: Yangang Xing et al 2018 IOP Conf. Ser.: Earth Environ. Sci. 121 022032
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EEEP2017 IOP Publishing
IOP Conf. Series: Earth and Environmental Science 121 (2018) 022032 doi :10.1088/1755-1315/121/2/022032
Growing and testing mycelium bricks as building insulation
Yangang Xing1,4 , Matthew Brewer2, Hoda El-Gharabawy 2,3, Gareth Griffith2
and Phil Jones1
1 Welsh School of Architecture, Cardiff University, CF10 3NB, UK;
2 IBERS, Cledwyn Building, Aberystwyth University, Aberystwyth SY23 3DD, UK ;
3 Botany and Microbiology Department, Faculty of Science, Damietta University, New
Damietta, EGYPT
Abstract. In order to improve energy performance of buildings, insulation materials (such as
mineral glass and rock wools, or fossil fuel-based plastic foams) are being used in increasing
quantities, which may lead to potential problem with materials depletions and landfill disposal.
One sustainable solution suggested is the use of bio-based, biodegradable materials. A number
of attempts have been made to develop biomaterials, such as sheep wood, hemcrete or recycled
papers. In this paper, a novel type of bio insulation materials mycelium is examined. The aim
is to produce mycelium materials that could be used as insulations. The bio-based material was
required to have properties that matched existing alternatives, such as expanded polystyrene, in
terms of physical and mechanical characteristics but with an enhanced level of biodegradability.
The testing data showed mycelium bricks exhibited good thermal performance. Future work is
planned to improve growing process and thermal performance of the mycelium bricks.
1. Introduction
Building insulation plays an important role in improving thermal comfort, health and wellbeing of
occupants and reducing heating and cooling energy consumptions, carbon emissions and pollutions [1].
However, most of the buildings insulation materials are manufactured using mined and/or fossil fuel-
based materials. In this study, we prepared and tested alternative building insulation materials. We
selected three species of basidiomycete fungi and used these to grow mycelium bricks on straw waste.
Dual-needle probes are used to measure the thermal conductivity and specific heat capacity. It is based
on the transient hot wire method in which a small constant heat pulse is supplied to the sample through
a heating probe and the rise in temperature is noted by a sensing probe located at a fix distance from
the heating probe. We carried out preliminary thermal characterisation tests. The paper concludes
with a discussion on future research needs in this area.
2. Fungi species and growing process
2.1. Basic information about the fungi
The realm of Fungi is a diverse kingdom, with members of the phylum Basidiomycota exhibiting a
range of ecological strategies, ranging from the familiar edible or poisonous mushrooms to human and
plant pathogens. However, a key feature restricted to certain members of this phylum is the ability to
EEEP2017 IOP Publishing
IOP Conf. Series: Earth and Environmental Science 121 (2018) 022032 doi :10.1088/1755-1315/121/2/022032
decay lignin and as such a wide range of basidiomycetes have been studied as agents of wood decay.
In the past, most research activities have focused on elucidating the mechanisms of lignocellulose
degradation both in an ecological context and also to mitigate the harmful effects of such fungi for
instance in wooden buildings etc. [2]. The use of wood decay fungi for colonizing waste materials has
received limited attention. Here we explore the potential of waste materials partially colonized by
white rot fungi as potential thermal insulation material.
2.2. Species selected in this experiment
Three species of basidiomycete fungi (order Polyporales) were chosen because they were known to
grow quickly on agar media and to be powerful colonisers and degraders of lignocellulose (table 1).
All were originally isolated from trees (both live and dead) in the Nile Delta region of Egypt (El-
Gharabawy, 2016). All grew rapidly (8.7-13 mm/day at 25oC on 3% Dark Malt Extract Agar
Table 1. Species.
Oxyporus latermarginatus
Megasporoporia minor
Ganoderma resinaceum
2.3. Growing environment, substrate , nutrient, and growing process
In this section, basic information regarding fungi, and growing environment, and the end products will
be described. Fungal cultures were routinely cultivated on 3% DMEA and incubated at 28oC. For the
bulking up of inoculum, 10 g rye grains and 10 ml water were placed in a 25 ml glass (Universal) vial
and sterilised by autoclaving (115oC/15 min). When cooled the rye grains were inoculated at 28oC
with three plugs of mycelium from agar plate cultures, and the lids capped loosely to allow air
exchange. After 14 days, the rye grains were well colonised and then used to inoculated wheat straw
cultures. The orientation of straws was randomly placed (as shown in figure 1).
Straw cultures were established in polycarbonate plant tissue culture vials (Magenta GA7;
77x77x97 mm; Sigma). Wheat straw was cut to 3-4 cm lengths and dispensed 20 g per vial with 40 ml
water added to each vial. Vials were autoclaved (115oC/15 min) and after cooling down, inoculated
with 6-8 colonised rye grains spread around the vial. Cultures were incubated at 28oC for 8 weeks with
the vial lids slightly opened to allow air exchange. No any resins are used in the process. Straw blocks
were removed from the culture vials and dried at 70oC. They showed some loss of fresh weight, dry
weight, and differences in density as in table 2:
Table 2. Weight losses, volume, and density.
weight1 (g)
Fresh weight
loss (%)
Dry weight
loss (%)
Dry Mass
Volume (cm3)
1Initial fresh weight was 60 g (20g wheat straw/40 g water)
EEEP2017 IOP Publishing
IOP Conf. Series: Earth and Environmental Science 121 (2018) 022032 doi :10.1088/1755-1315/121/2/022032
The appearance of the colonized wheat straw differed between the three species. GAN
preferentially colonized the outer parts of the substrate. The exact reason for this is not clear but may
show an avoidance of areas of higher CO2 concentration (with CO2 formed from fungal metabolism).
However, the pattern of mycelial growth may be in response to other gradients within the culture
vessel (e.g. moisture, O2). Different species also exhibit different wood colonization strategies for
other reasons, for example to protect outer boundaries of the colony from attack by other fungi. In any
event colonization of the core of the wheat straw block was poorer than for other species and this is
reflected in the physical properties of the mycelial block. In terms of substrate decay, GAN exhibited
the greatest dry weight loss over the 8 week incubation period, consistent with the pattern of enzyme
production on ashwood sawdust that was observed (as shown in table 3) for this isolate by El-
Gharabawy [3].
The pattern of wheat straw colonization was similar for OXY and MEG with even more
colonization across the centre of the block. In both cases there was more growth at the top of the
culture vessel (where the air vents were located). In the case of OXY, initial growth (weeks 1-2) was
predominantly visible at the top of the culture vessel with colonization of the lower layers of wheat
straw occurring later.
Table 3. Growth rates reproduced from [3]
RGR Radial
Growth Rate
(N 31.2611 E31.4648)
UNIV.(N31.0403, E31.3590)
(N31.0637, E31.6577)
As shown in figure 1, the three isolates used here grow maximally at 30ºC (GAN and OXY) or
33ºC (MEG) on agar plates so in all three cases incubation at higher temperatures would likely lead to
more rapid substrate colonisation (and thereby shorter incubation periods for mycelial block
preparation maybe as low as 4 weeks). Growth at different temperatures may also alter patterns of
ligninolytic enzyme production which in turn would alter patterns of substrate decay and possibly lead
to differences in the thermal properties of the mycelial blocks. The final mycelium thermal blocks are
shown in figure 2.
Figure 1. Radial growth rate of isolates at different temperatures (upper row is GAN,
middle is MEG, lower is OXY).
EEEP2017 IOP Publishing
IOP Conf. Series: Earth and Environmental Science 121 (2018) 022032 doi :10.1088/1755-1315/121/2/022032
Figure 2. Three Specimens.
3. Preliminary transient thermal testing
3.1. Transient thermal measurement approach
In order to determine basic thermal characteristics (i.e. thermal conductivity k-value and specific heat
capacity) of the mycelium blocks, KD-2 Pro thermal analyser (model KD-2 Pro, Decagon Device, Inc.)
was used as shown in figure 3. High accuracy, shorter measurement time and easy to use are the main
advantages of this method [4]. There are commonly two types of thermal needle probe: single and
dual-needle. In this study, we have used dual-needle probe. Heat is applied to the heated needle for a
set heating time, th, and temperature is measured in the monitoring needle, 6 mm distant during
heating and during the cooling period following heating. The readings are then processed by
subtracting the ambient temperature at time 0, multiplying by 4π and dividing by the heat per unit
length, q. The resulting data are were fitted to the following equations [5] using a nonlinear least
squares procedure [6] which is calculated using the KD 2 Pro Analyszer.
Ei is the exponential integral, and bo, b1 and b2 are the constants to be established. To is the
temperature at the start of the measurement and q is the heat input. The first equation applies for the
first th seconds, while the heat is on. The second equation applies when the heat is off. Compute
thermal conductivity from Equation 4 and diffusivity from 5.
where, k is thermal conductivity, D is specific heat capacity, r is the distance between the heater
and the sensor where temperature is measured.
EEEP2017 IOP Publishing
IOP Conf. Series: Earth and Environmental Science 121 (2018) 022032 doi :10.1088/1755-1315/121/2/022032
Figure 3. Thermal properties measurement.
3.2. Preliminary thermal test results and limitations
Four tests were carried to each specimen placing the dual needle probes in different directions. The
average thermal conductivity and specific heat capacity readings are listed in table 4. Thermal
conductivity measures the ease with which heat can travel through a material by conduction.
Conduction is the main form of heat transfer through insulation. The lower the figure, the better the
performance. In general, a good insulator has a higher Specific Heat Capacity because it takes time to
absorb more heat before it actually heats up (temperature rising) to transfer the heat. High Specific
Heat Capacity is a feature of materials providing Thermal Mass or Thermal Buffering (Decrement
Delay). Based on this experiment, OXY has the best thermal insulation performance (lowest thermal
conductivity). GAN has the worst thermal insulation performance (i.e. higher thermal conductivity and
lowest specific heat capacity).
TABLE 4. Thermal performance.
Thermal conductivity
Specific Heat Capacity
Nevertheless, the measured thermal conductivities of these three specimens measured in this paper
are similar (0.074-0.087 W/mK). A study demonstrated that the decrease of the thermal conductivity
of a hay bio-composite is proportional to the decrease of its bulk density, the latter depending on the
increase of fibres in the mix [4]. Comparing with other light weight synthetic insulation materials,
such as polystyrene (density 2845 kg/m3), thermal conductivity varies between 0.029 and 0.039
W/mK [7] [8]. However, the mycelium bricks is performing better than some other biocomposite
materials, such as raisin-based bio-composite 0.09179 W/mK to 0.1534 W/mK [9].
Transient thermal analyses have been utilized in a number of porous insulation materials studies
[10-12], however, it should be noted the high porosity of the mycelium materials tested in this study
may cause readings to become inaccurate, future calibration and steady-state testing, such as guarded
hot plate or hot box may is needed.
EEEP2017 IOP Publishing
IOP Conf. Series: Earth and Environmental Science 121 (2018) 022032 doi :10.1088/1755-1315/121/2/022032
4. Discussion and conclusions
4.1. Selection of fungal species, growing substrates and growing environment
From this study, it can be seen that different species have dramatically different of growth patterns
within the substrate and bonding. Thus, it is important to select appropriate fungi species to form
building insulation materials. In choosing suitable fungi, several factors must be considered: rapid
mycelial growth to bind the substrate is desirable but rapid rates of substrate decay (as found here for
GAN) are less desirable (potentially weakening the blocks). Even growth at the edges and in the
middle of the substrate blocks is also desirable (as shown here for OXY and MEG). These patterns of
growth presumably reflect the nature of substrate colonisation by these fungi in nature. El-Gharabawy
[3] investigated the spatial patterns of enzyme production by these three fungi on cellophane strips.
MEG and OXY produced greatest levels of ligninolytic activity (bleaching of dye) in older zones of
mycelial growth, whereas GAN generally secreted these enzymes in a more patchy manner (and less
so in areas initially colonised).
4.2. Improvement of the growing process
The cultures used here originated from a warm subtropical climate (Nile Delta region, Egypt) and all
three grow well at 33oC so could potentially be grown at 5oC warmer than the temperature used for
these trials allowing more rapid colonisation of straw or other substrate, possibly in as little as 4
Choice of fungi species also needs to consider the degradation rate of straw (as main type of
biomass residuals). It is desirable to have rapid colonisation of straw or other lignocellulosic substrate.
However, excessive degradation of the substrate could lead to weakening of the straw block. The
isolates differ in their growth rates on agar and also on wood but these growth rates do not necessarily
correlate with the extent of dry weight loss. This is because these fungi differ in their colonisation
Currently the authors are investigating a number of approaches to improve the thermal insulation
performance of the light weight mycelium materials. Future experiments are needed to improve the
density of the substrates using fine powder, higher density material to increase the overall weight
providing 'low' thermal diffusivity and 'high' thermal mass in order to create a nature-based solution to
the built environment [13]. Based on the transient thermal conductivity tests, all three specimens
exhibit relatively similar thermal characteristics. There is no significant difference between the three
specimens based on this type of tests, the next stage is to carry out research on fireproofing methods
(e.g. adding flame retardants or gypsum and cementitious plasters).
Authors wishing to acknowledge assistance or encouragement from colleagues, special work by
technical staff or financial support from the Welsh Government and Higher Education Funding
Council for Wales through the r Cymru National Research Network for Low Carbon, Energy and
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... Developed mycelium block. FromXing et al., 2018. ...
... Moreover, Xing et al. (2018) examined the possibility of using mycelium materials as insulators to improve the energy performance of buildings. Thereby, a novel type of bio-insulating material (Fig. 7.7) was successfully prepared as an alternative to expanded polystyrene. ...
Most mushroom farming has been carried out using classical farming practices, giving one of the main reasons for low mushroom yield; in traditional mushroom farms routine practices are more labor intensive. Moreover, controlling insects, pests, and diseases is much more challenging and needs more vigilance. However, adapting innovative agricultural techniques can improve overall efficiency and productivity at a mushroom farm. One of the most advanced technologies is the application of the Internet of Things (IoT), which provides remote access to daily farm operations, and insect and pest control to the farmers. This sensor-based technique can be used to monitor crucial environmental factors including humidity, light, moisture, and temperature at a mushroom farm. The long-term benefits of semi- or fully automated farms result in high productivity, less labor, and reduced cost of production. Aside from the surrounding environmental conditions, controlling biotic stresses is also a challenging task at a mushroom farm. These may include insect pests, fungi, bacteria, nematodes, and some viral diseases. The use of synthetic chemical products at a mushroom farm can be hazardous to mushroom cultivation; thus, integrated pest management (IPM) and use of modern molecular approaches to confer natural resistance to biotic stresses can be effective control measures.
... There are two main types of mycelium-based materials: pure mycelium materials and mycelium-based composites. Pure mycelium materials are generally used and studied for smaller-scale applications such as paper or textile making [33,34] and biomedical applications such as wound healing [35] and tissue engineering [36]. Mycelium-based composites are made by growing the mycelium homogeneously in and around organic waste materials and are generally used for mesoscale modular applications such as bricks [37], thermal insulation, or acoustic panels [38,39], and low-value materials such as packaging [40]. ...
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Wood decay fungi found on living or dead trees in fruit orchards in the Nile Delta region of Egypt were isolated into pure culture and their ligninolytic capabilities examined. Growth on ash sawdust was monitored by quantification of ergosterol and laccase/peroxidase activities using the model substrate ABTS. Two species from the polyporoid clade of order Polyporales exhibited faster growth and greater enzymatic activity than two isolates from the phlebioid clade but these differences were not reflected in dry weight loss of wood. Cellophane strips impregnated Remazol Brilliant Blue dye and MnCl 2 impregnated plates were used to show the distinctive spatiotemporal patterns for the four species.
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Building insulation is commonly realized using materials obtained from petrochemicals (mainly polystyrene) or from natural sources processed with high energy consumptions (glass and rock wools). These materials cause significant detrimental effects on the environment mainly due to the production stage, i.e. use of non-renewable materials and fossil energy consumption, and to the disposal stage, i.e. problems in reusing or recycling the products at the end of their lives. The introduction of the concept of “sustainability” in building design process encouraged researches aimed at developing thermal and acoustic insulating materials using natural or recycled materials. Some of them, such as kenaf or wood fiber, are already commercialized but their diffusion could be further improved since their performance are similar to the synthetic ones. Others are currently under study and their development is only at an early stage. The goal of the paper is to report a state of the art of building insulation products made of natural or recycled materials that are not or scarcely commercialized. Comparative analyses were carried out considering in particular thermal characteristics in terms of thermal conductivity, specific heat and density. Data on the acoustic performance of the materials were also reported. Life Cycle Assessment data were finally collected, in order to put in evidence the environmental advantages of these materials. Particular attention was paid to researches focused to exploit local materials and even industrial byproducts, since these approaches respectively limit transportation and disposal impacts.
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There is increasing work on the use of flax fibers as reinforcement for manufacturing composites because of their lower cost and environmental benefit. During manufacturing of such natural fiber–plastic composites, heat transfer is involved, but information about the thermal conductivity and thermal diffusivity at the processing temperatures is not available. In this study, the thermal conductivity, thermal diffusivity, and specific heat of flax fiber–high density polyethylene (HDPE) biocomposites were determined in the temperature range of 170–200°C. The fiber contents in biocomposites were 10%, 20%, and 30% by mass. Using the line-source technique, the instrumental setup was developed to measure the thermal conductivity of biocomposites. It was found that the thermal conductivity, thermal diffusivity, and specific heat decreased with increasing fiber content, but thermal conductivity and thermal diffusivity did not change significantly with temperature in the range studied. The specific heat of the biocomposites increased gradually with temperature.
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With restrictions for environmental protection being strengthened, thermoplastics reinforced with natural fibers such as jute, kenaf, flax, etc., have replaced automotive interior materials such as chemical plastics. In this study, the thermal conductivity of several kinds of thermoplastic composites in the form of board composed of 48.5mass% polypropylene (PP) and 48.5mass% natural fiber (NF), and reinforced with 3.0mass% maleated polypropylene (MAPP) and 0.3mass% silane as the coupling agents, were measured at temperatures of −10, 10, and 30°C, using a heat flow meter apparatus. The results show that the thermal conductivity is in the range of 0.05–0.07W·m−1·K−1, and the thermal conductivity increased about 10–15% by adding MAPP and about 10–25% by soaking in a silane aqueous solution. The tensile strength was also measured, and the result shows similar trends as the thermal conductivity.
The energy consumption of a building is strongly dependent on the characteristics of its envelope. The thermal performance of external walls represents a key factor to increase the energy efficiency of the construction sector and to reduce greenhouse gases emissions. Thermal insulation is undoubtedly one of the best ways to reduce the energy consumption due to both winter heating and summer cooling. Insulation materials play an important role in this scenario since the selection of the correct material, its thickness and its position, allow to obtain good indoor thermal comfort conditions and adequate energy savings. Thermal properties are extremely important, but they are not the only ones to be considered when designing a building envelope: sound insulation, resistance to fire, water vapor permeability and impact on the environment and on human health need to be carefully assessed too. The purpose of the paper is to provide a review of the main commercialized insulation materials (conventional, alternative and advanced) for the building sector through a holistic and multidisciplinary approach, considering thermal properties, acoustic properties, reaction to fire and water vapor resistance; environmental issues were also taken into account by means of Life Cycle Assessment approach. A comparative analysis was performed, considering also unconventional insulation materials that are not yet present in the market. Finally a case study was conducted evaluating both thermal transmittance and dynamic thermal properties of one lightweight and three heavyweight walls, with different types of insulating materials and ways of installation (external, internal or cavity insulation). Free access until July 8, 2016 at
Thermochemical conversion of OPS has gained huge attention among the researchers mainly because it converts the waste OPS into energy rich value added by-products. Thermophysical properties play a very crucial role in the thermal treatment of OPS and govern the heat transfer phenomenon of the material. Temperature dependence of thermophysical properties of OPS and OPS char has been investigated within the temperature range between 30 and 110 °C. OPS char is synthesized by the microwave pyrolysis of OPS. Thermogravimetric analysis of OPS and OPS char confirmed that OPS is more thermally stable as compared to OPS char. Moreover, it gave information about the degradation behavior of OPS and OPS char. Thermophysical properties was measured by thermal analyzer, based on the transient hot wire technique which is suitable to measure the thermal conductivity at elevated temperatures. At room temperature, thermal conductivity and thermal diffusivity of OPS are 0.199 W/m K and 0.142 mm2/s respectively and are 15.07% and 12.67% higher than that of OPS char. Specific heat capacity of OPS and OPS char are found to be almost same (1.139 kJ/kg K for OPS and 1.108 kJ/kg K for OPS char). Thermal conductivity and thermal diffusivity values lowered on increasing the temperature while specific heat capacity increased linearly on increasing the temperature. Low thermal conductivity and thermal diffusivity values of OPS implies that the conventional conductive heating is less effective and inefficient for the thermal treatment of OPS.
Ready access to reliable low cost instrumentation for use in laboratory and field experimentation remains a priority for many working in the soil and environmental sciences area. In this paper we provide an overview of the multi-needle heat-pulse probe which can now provide measurements of soil temperature, soil thermal diffusivity, volumetric heat capacity, thermal conductivity, volumetric water content, and bulk soil electrical conductivity, all at the same position and time. We show that the multi-needle probe can provide high quality measurements, in some cases as good as or better than those obtained using other current methodology. As an example, multi-needle probes have been shown to yield measurements of volumetric water content with a root mean square error of 0.01 m3 m−3. Because of its small size the multi-needle probe should prove particularly useful for measurements near the soil surface, near to plant roots, and in other situations requiring fine spatial resolution in measurements. These probes can also be easily automated for unattended use to facilitate data collection as a function of time and space. We also highlight issues that need further analysis and research in helping guide further development of more robust multi-needle probe designs, especially for field applications.
Buildings account for almost half of energy consumptions in European countries and energy demand in building continues to grow worldwide. Fossil fuels are finite reserves. Impacts of peak oil will be perceived soon or later in the next decades. The scale of the challenge in reducing fossil fuel dependency in the built environment is vast and will require a dramatic increase in skills and awareness amongst the construction professions. Building refurbishment towards zero carbon is established itself as one critical aspect to decouple from fossil fuels and tackle with future energy crisis. However, it is a very complex phenomenon cuts across disciplines. This paper categorises a range of technologies for building refurbishment in a sequential manner. A hierarchical process with embedded techniques (insulations, energy efficient equipment and micro-generation) is presented in this paper as a pathway towards zero-carbon building refurbishment.