design and performance assessment of building counter walls integrating moisture buffering active devices

Abstract The use of building materials with high moisture buffering capacity is a well-recognized strategy to moderate the variation of indoor moisture loads. Many researchers investigated the ability and potential of finishing materials and furniture for the reduction of the amplitudes of indoor relative humidity by characterising their Moisture Buffering Value. Nevertheless, the recent and widespread building practice, which is increasingly trying to reduce the air permeability and thermal transmittance of the envelope, is likely to even worsening indoor humidity conditions, with consequences for durability of materials and inhabitants' comfort and health. Very performing materials are then needed to act as buffering and quickly dampen high moisture loads. This paper proposes the design of a building internal counter wall equipped with an "active" moisture buffering device. This is able to measure the indoor relative humidity and consequently increase the adsorbing capacity of a porous material through an air-flow. Experimental activities were carried out on different prototypes with the combination of granular Sepiolite with two different pore structures and nonwoven fabrics. The devices effectiveness in terms of MBV has been dynamically tested in a climate chamber according to the DTU Nordtest method. Different "activation" times against several humidity levels were set in order to assess the best solution in different scenarios

design of a smart system for indoor climate control in historic underground built environment

Abstract The application of sensors-actuators networks in Building Heritage can lead to significant improvement in indoor climate control, with the aim to both reduce energy consumption, and improve conditions for occupants and hosted Heritage. This study proposes the preliminary design of a smart indoor climate control system, based on low-impact application criteria, which can be applied to visited underground built environment. The system is based on the balance of hygrothermal loads. Sensors and actuators requirements are defined, and control algorithm are based on the comparison between real-time monitored and "natural" temperature and hygrometric values (for stationary and transitory conditions)

Effect of temperature and relative humidity on algae biofouling on different fired brick surfaces

Abstract The purpose of this study was to evaluate the effect of environmental temperature and relative humidity on algae biofouling that often occurs on porous and rough fired brick surfaces. Brick samples were chosen since their common use on building facades. Accelerated growth tests were performed under different relative humidities and different temperatures. Results showed the effects of different temperature conditions in terms of algae growth delay and reduction of the covered area. All the relative humidity conditions tested substantially showed no growth from an engineering standpoint. The modified Avrami's law succeeded in modelling the biofouling under the different environmental conditions

A novel Failure Model to predict Biofouling (Algae Growth) on Different Building Facades under Different Environmental Conditions

L’involucro edilizio è spesso soggetto, sul lato esterno, ad un degrado causato dalla crescita algale, il quale rende necessari interventi di manutenzione ed una serie di costi da sostenere. L’attività biologica sulle facciate è principalmente dovuta alla colonizzazione da parte di alghe verdi e cianobatteri, che possono successivamente favorire la proliferazione di altri microorganismi, come muffe e licheni. Sono pochi gli studi hanno investigato le condizioni favorevoli allo sviluppo algale sui materiali da costruzioni e per questo manca ancora un modello di danno legato a tale fenomeno. In questa ricerca viene presentato un modello matematico, basato su risultati sperimentali e sulla legge di Avrami, capace di predire la crescita algale sui materiali edili esposti alle condizioni ambientali tenendo in conto delle proprietà del substrato. La crescita algale è stata studiata su laterizi, attraverso test accelerati in diverse condizioni ambientali di temperatura e umidità relativa. Si è notato che la temperatura influenza notevolmente il tasso di crescita (area coperta in funzione del tempo) e che ad umidità relative minori del 98% non si riscontra alcuna crescita. Substrati altamente porosi e rugosi, invece, favoriscono la colonizzazione, accelerando il processo di crescita e quindi anche il degrado. Il modello di danno ottenuto si compone di varie equazioni che descrivono il tasso di crescita algale su substrati in condizioni ambientali, considerando l’effetto del tempo di esposizione, della temperatura e dell’umidità relativa. I parametri e i valori numerici presenti nel modello sono stati fittati per laterizi e pietre, ma il modello può essere ritenuto valido anche per altri materiali da costruzione. Inoltre, l’implementazione del modello in un software di simulazione aiuterebbe a prevedere il degrado sulle facciate degli edifici e la programmazione di manutenzione in specifici contesti climatici.The building envelopes are often exposed to algal biofouling, that causes the deterioration of the materials’ surface, with consequence in economic loss due to the building maintenance. Biofouling on façades is firstly due to the algal colonization, mainly promoted by green algae and cyanobacteria, that also can favour the proliferation of other microorganisms (i.e. moulds, lichens). Only few studies tried to investigate the suitable conditions for algae to grow on construction materials, hence a failure model has not been implemented yet. This research tried to fill this gap by presenting a mathematical model able to predict algae growth on building materials exposed to the environmental conditions and considering the substrate properties. The failure model was based on experimental results and on the Avrami’s law. Algae biofouling was investigated on fired brick substrates, through accelerated growth tests under different environmental conditions of temperature and relative humidity. It was found that temperature mainly influenced the algae growth rate (covered area as a function of time), while at relative humidity lower than 98% no growth activity was detected. Regarding the effect of the substrate, roughness and high porosity favoured the colonization in terms of velocity of the growth process. The quantification of algae biofouling was based on the covered area measured during the experiments. The model consists of several equations describing the growth rate by algae on the substrates under different environmental conditions, including the effect of exposure time, temperature, relative humidity. The parameters and the numerical values included in the model were fitted for bricks and stones, but the model can be valid also for other building materials. Moreover, if implemented into a simulation software, the biofouling process on façades could be predicted, and it could help in providing guidelines for intervention and maintenance techniques in specific context

Design of a smart system for indoor climate control in historic underground built environment

The application of sensors-actuators networks in Building Heritage can lead to significant improvement in indoor climate control, with the aim to both reduce energy consumption, and improve conditions for occupants and hosted Heritage. This study proposes the preliminary design of a smart indoor climate control system, based on low-impact application criteria, which can be applied to visited underground built environment. The system is based on the balance of hygrothermal loads. Sensors and actuators requirements are defined, and control algorithm are based on the comparison between real-time monitored and “natural” temperature and hygrometric values (for stationary and transitory conditions)