Promoting bio-based building materials as a means of bridging the urban-rural divide in Serbia

Due to the difficult economic situation within Serbia, rural areas find themselves on the margins of investment and development, creating a deep rural-urban divide. Much of Serbia can be characterized as rural with a large segment of the population living in rural settlements defined by socio-economic stagnation or degradation. Revitalizing rural regions is thus important for the socio-economic wellbeing of the entire country and mitigating the rural-urban divide can be key to the sustainable development of urban areas. Much of the built environment in Serbia has a low level of energy efficiency and though public perception has improved, the focus is on improving operational energy, while the embodied environmental impact of building materials is rarely considered. This paper details and analyses the main problems facing rural areas in Serbia. As agriculture is still the primary economic activity in rural areas, it suggests that the development and application of bio-based building materials created from the by-products of agriculture, can be an important element of further strategies for sustainable development in Serbia. In particular industrial hemp, which was once an important and abundant crop in Serbia, is currently experiencing a significant resurgence. This paper demonstrates that hemp-lime concrete may be a particularly suitable building material for encouraging new economic activity in rural areas and promoting sustainable design in both rural and urban areas

Creating life cycle assessment models for hemp lime concrete in the context of Serbia

Грађевинска индустрија је заслужна за значајне емисије материја које негативно утичу на животну средину. Суочени са климатским променама и другим еколошким проблемима примена еколошки одрживијих грађевинских материјала постаје високи приоритет. Грађевински материјали на биолошкој основи могу бити еколошки исправни пошто могу да користе обновљиве сировине које током развоја везују угљен диоксид фотосинтезом и на крају животног века се могу разградити или рециклирати. Током XX и почетком XXI века стратегије еколошке одрживости и енергетске ефикасности нису значајно разматране у градитељској пракси у Србији. Увођењем „Правилника за енергетску ефикасност зграда“ у 2011. години формиран је оквир за смањивање потрошње оперативне енергије у објектима, али уграђени еколошки утицаји који су последица грађевинске праксе су и даље формално запостављени. Упоредо са све већим интересовањем за узгој индустријске конопље, бетон од конопље и креча је идентификован као потенцијално еколошки исправан грађевински материјал који се може применити у новоградњи, енергетској санацији постојећих објеката и рестаурацији објеката градитељског наслеђа. Формира се мешањем поздера индустријске конопље са композитним везивом на бази креча и водом и превасходно користи за изградњу зидова у комбинацији са дрвеном конструкцијом око које се материјал излива. Применом методологије процене животног циклуса истраживање циља да дефинише еколошки утицај животног века бетона од конопље и креча у контексту Србије. Кроз серију анализа осетљивости које испитују еколошке утицаје варирања кључних параметара попут фактора везивања CO2 у поздеру, фактора карбонатизације везива, приноса индустријске конопље, раздаљине превоза сировина на локацију и степена формирања грађевинског отпада приликом изградње формирана су три основна сценарија која указују на широк спектар еколошких утицаја животног циклуса зида од бетона од конопље и креча. Испитани су и еколошки утицаји различитог степена разградње поздера на крају животног века, префабрикације бетона од конопље и креча у блокове и различитих стратегија обраде зида. Поређењем са животним циклусом типичне грађевинске праксе у новоградњи и санацији стамбених објеката у Србији, уочено је да је бетон од конопље и креча еколошки исправан грађевински материјал и да је супериоран у готово свим анализираним еколошким показатељима.The construction industry is responsible for significant emissions of substances that negatively impact the environment. Faced with climate change and other environmental issues, the use of more environmentally sustainable building materials has become a high priority. Bio-based building materials can be environmentally sustainable as they can make use of renewable raw materials that sequester carbon dioxide through photosynthesis and can biodegrade or be recycled at end of life. During the XX century and beginning of the XXI century the concepts of environmental sustainability and energy efficiency weren’t particularly considered in the Serbian construction industry. With the implementation of the “Rulebook for the energy efficiency of buildings” in 2011 a framework for the reduction of operational energy in buildings was formed, but the embodied environmental impacts of construction practices are still formally neglected. In conjuction with the rising interest for growing industrial hemp, hemp-lime concrete is identified as a potentially environmentally sustainable building material that can be used in new builds, the energy renovation of existing buildings and the restoration of historical buildings. It’s formed by mixing industrial hemp shives with a composite lime based binder and water and is primarily used for the construction walls by casting around a timber stud frame. Using life cycle assessment methodology the study aims to define the life cycle environmental impacts of hemp-lime concrete in the context of Serbia. Through a series of sensitivity analyses that examine the environmental imapacts of varying key parameters like the hemp shiv carbon dioxide sequestration factor, binder carbonation factor, industrial hemp yield, material transport distance and building site waste formation rate, three primary scenarios demonstrating the wide range of environmental impacts ofassociated with the life cycle of hemp-lime concrete wall are developed. The environmental impacts of variable hemp shiv degradation factors at end of life, prefabricating hemp-lime concrete into blocks and various wall finishes were also examined. Through comparisons with the life cycle of typical residential construction practices in Serbia, it is observed that hemp-lime concrete can be considered an environmentally sustainable building material and that it is superior in virtually all of the examined environmental impact categories

Life cycle assessment of hemp-lime concrete wall constructions: The impact of wall finish type and renewal regimes

Using sustainable building materials is one of the key methods for minimising the negative environmental impacts of the global construction industry. Bio-based buildings building materials, such as hemp-lime concrete, are considered more sustainable, as they make use of a renewable raw material and can sequester CO2 from the atmosphere. Studies have shown that hemp-lime concrete can have a favourable global warming potential, though the life cycle of building materials affects a wide variety of negative environmental phenomena that should also be considered. Studies examining the life cycle of hemp-lime concrete have so far primarily focused on the material itself. Though the exterior surface of a hemp-lime concrete wall needs to be protected and have a finish applied to it, few studies have considered the environmental impacts of coated hemp-lime concrete wall constructions. Using life cycle assessment methodology, through a wide range of environmental impact categories, the study analysed the environmental impacts of applying lime putty and sand coatings to a hemp-lime concrete wall in pessimistic, average and optimistic scenarios, It also compared the environmental impacts of four types of appropriate wall finishes and the impacts of applying varying finish renewal regimes in the use phase. It was found that applying lime putty and sand finishes to the exterior and interior surface of a hemp lime concrete wall increased the total global warming potential by 19.054–30.793 kgCO2eq and had a noticeable effect on all other impact categories. It was found that while no one finish type could be considered globally superior to the others, in a majority of circumstances applying lime-based coatings resulted in lower embodied environmental impacts, than applying a ventilated façade with timber cladding

Life cycle greenhouse gas emissions of hemp-lime concrete wall constructions in Serbia: The impact of carbon sequestration, transport, waste production and end of life biogenic carbon emission

The construction industry contributes to climate change through significant greenhouse gas emissions. Utilising sustainable building materials with low embodied environmental impacts and low greenhouse gas emissions is key to future sustainable development. Bio-based materials, such as hemp-lime concrete, possess environmental advantages as they make use of a renewable raw material and can sequester CO2 from the atmosphere. Through the use of life cycle assessment methodology the study analyses the greenhouse gas emissions associated with the life cycle of a hemp-lime concrete wall and examines the effects of variations that can arise during the life cycle of the material. Sensitivity analyses were used to examine the effects of varying the hemp shiv sequestration factor, binder carbonation factor, gate to site transport distances and raw material construction waste on greenhouse gas emissions, culminating in the creation of three primary emission scenarios (average, pessimistic and optimistic). It was found that the examined variables can have a large impact on greenhouse gas emissions and the environmental perception of the material, as the optimistic life cycle scenario had a negative global warming potential (−9.696kgCO2eq.), while the pessimistic scenario had a positive global warming potential (10.165kgCO2eq.). Additionally alternative end of life scenarios were developed to examine the effects of varying hemp shiv degradability at the end of life stage, demonstrating the potentially large impacts a high factor of degradable organic carbon can have on life cycle greenhouse gas emissions