Passive House in Gijón

Description Passivhaus certification for a single-family detached home in Gijón, Asturias, designed by architect Juan Ignacio Corominas. The house has a treated floor area of 285 m2 distributed over a ground floor and a semi-basement. The construction system is mixed, combining honeycomb brick walls with external insulation, and a timber roof structure with 28cm of …

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Passivhaus

Passive House in Gijón

Description

Passivhaus certification for a single-family detached home in Gijón, Asturias, designed by architect Juan Ignacio Corominas.

The house has a treated floor area of 285 m2 distributed over a ground floor and a semi-basement. The construction system is mixed, combining honeycomb brick walls with external insulation, and a timber roof structure with 28cm of thermal insulation. Window frames are aluminum, Passivhaus certified, Cortizo COR 80. As part of the audit, Praxis verifies all the calculations and design documentation presented by the Passivhaus Consultant, which include architectural and M&E drawings and reports, the PHPP calculation, the Blower Door test report, ventilation commissioning documentation and photographs of the construction process and completed building.

Year: 2021

Location Gijón, Asturias

Services: Passivhaus Certification

Blower Door in Viladecans

Description Blower Door airtightness test to the EN 13829 (A/B) standard for the verification of whole building airtightness, as part of the deep energy retrofit of a single-family terraced home in Viladecans, Barcelona.  The house is in the process of Passivhaus EnerPHit certification and has been designed by Daniel Tigges of Tigges Architekt. Two tests …

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Blower Door

Blower Door in Viladecans

Description

Blower Door airtightness test to the EN 13829 (A/B) standard for the verification of whole building airtightness, as part of the deep energy retrofit of a single-family terraced home in Viladecans, Barcelona. 

The house is in the process of Passivhaus EnerPHit certification and has been designed by Daniel Tigges of Tigges Architekt.

Two tests were carried out: during construction and following completion. For the preliminary test, leaks were detected with a handheld smoke generator and anemometer.

The final result of N50=0.55/h, is well below the minimum requirements of the Spanish building regulations CTE DB HE-1 2019 and almost 50% lower the minimum requirements of the Passivhaus EnerPHit standard (where the limiting value for existing buildings is N50 ≤ 1/h).

Year: 2021

Location: Viladecans, Barcelona

Services: Blower Door

Wine cellar and tasting room

Description Energy consultancy and M&E design for a wine cellar and tasting room in the Priorat region, Tarragona, designed by architect Èlia Vaqué. The winery consists of two modules, one underground, where wine is aged, and another above ground, where tastings are held: a total of 290 m2 gross floor area. Praxis has undertaken a thermodynamic …

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Energy consultancy, M & E engineering 

Wine cellar and tasting room 

Description

Energy consultancy and M&E design for a wine cellar and tasting room in the Priorat region, Tarragona, designed by architect Èlia Vaqué.

The winery consists of two modules, one underground, where wine is aged, and another above ground, where tastings are held: a total of 290 m2 gross floor area.

Praxis has undertaken a thermodynamic and daylighting study of the buildings, using DesignBuilder (EnergyPlus & Radiance), assessing temperature and relative humidity conditions in the wine cellar and analysing the risk of summer overheating in the tasting room. The results have been used in the design of the thermal envelope. We’ve also designed the M & E systems: mechanical ventilation with heat recovery, space heating and cooling, hot water production, and off-grid solar PV with batteries and backup generator. 

Year: 2021

Location: Els Guiamets, Tarragona 

Services:
Thermodynamic simulation, daylighting analysis, M&E design

Single-family home in Sitges

Description Passivhaus design and consultancy, M & E engineering, and M & E site supervision, for this detached house in Sitges, Barcelona, designed by the architecture firm Intercon. The home, of 884 m2 distributed over 3 floors, is in the process of Passivhaus Classic Certification. Praxis has delivered the PHPP modelling, design of the thermal …

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Passivhaus design & consultancy, Blower Door Tests, M & E design, Site supervision

Single-family home in Sitges

Description

Passivhaus design and consultancy, M & E engineering, and M & E site supervision, for this detached house in Sitges, Barcelona, designed by the architecture firm Intercon.

The home, of 884 m2 distributed over 3 floors, is in the process of Passivhaus Classic Certification.

Praxis has delivered the PHPP modelling, design of the thermal envelope and airtight layer, advice on low-impact materials, and analysis and optimisation of thermal bridges and construction details.

We’ve also designed the M & E systems: mechanical ventilation with heat recovery, space heating and cooling, hot water production, plumbing, wastewater & drainage, electrical services, telecommunications, control and monitoring. Praxis has also undertaken the Blower Door testing, on-site M & E supervision and on-site Passivhaus supervision and quality control.

Year: 2021

Location: Sitges, Barcelona

Services:
Passivhaus design & consultancy, Blower Door Tests, M & E design, Site supervision

Terraced houses in Santa Coloma de Farners

Description Passivhaus design and consultancy for 4 terraced houses in Santa Coloma de Farners, Girona, design and developed by the Quim Ferrer, de Ecospai. Each home has a gross floor area of around 165 m2, distributed over 3 floors, with an underground parking lot. They are built with healthy and low-impact materials, and are in …

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Passivhaus

Terraced houses in Santa Coloma de Farners

Description

Passivhaus design and consultancy for 4 terraced houses in Santa Coloma de Farners, Girona, design and developed by the Quim Ferrer, de Ecospai.

Each home has a gross floor area of around 165 m2, distributed over 3 floors, with an underground parking lot. They are built with healthy and low-impact materials, and are in the process of Passivhaus Classic certification.

Praxis has delivered the PHPP modelling, design of the thermal envelope and airtight layer, advice on low-impact materials, and analysis and optimisation of thermal bridges and construction details. Praxis has also undertaken on-site Passivhaus supervision and quality control.

Year: 2021

Location: Santa Coloma de Farners, Girona

Services:
Passivhaus design & consultancy, Site supervision

DHW + PV: solar PV top-up for domestic hot water

Energy consumption from DHW use is often higher than heating and cooling requirements in a residential Passivhaus. This is mainly due to the large losses inherent in storing and recirculating hot water, and because heating and cooling demands are very low.

DHW + PV: solar PV top-up for domestic hot water

Energy consumption from DHW use is often higher than heating and cooling requirements in a residential Passivhaus. This is mainly due to the large losses inherent in storing and recirculating hot water, and because heating and cooling demands are very low, thanks to an optimised fabric design that minimises thermal losses/gains. Reducing the net energy consumption of DHW in Passivhaus is therefore important.  

The article presents monitored data from a solar PV installation for a single-family certified Passivhaus in Girona, Spain, designed by Tigges Architekt and Energiehaus Arquitectos, with services installed by Progetic (Figure 1 & Figure 2). The system diverts surplus PV production to an electric immersion heater in the DHW tank, where the primary generator for hot water is an air-source heat pump.  

Figure 1: View of the south façade of the case study home [Source: Loxone]
Figure 2: View of the east façade of the case study home [Source: Loxone]

The first step is always to optimise DHW system design and reduce losses. The second step is to find simple and low-maintenance solutions for on-site renewable energy generation for DHW production. The solution implemented here is an all-electric system that reduces net hot water energy consumption, using a solar PV array to top up hot water production, with an air-source heat pump as the main hot water generator. The system avoids the maintenance problems found in solar thermal systems that are susceptible to overheating in summer months when occupants are away, where fluid dry-up in the primary circuit between panel and tank is a frequent cause of failure. 

A series of calculations were done with the PHPP tool, to determine useful energy demands, final energy consumption and projected energy bills, by category. For the calculation of the energy bill, the weighted price of electricity was calculated at € 0.21 / kWh. Additionally, an analysis of DHW demand and losses by category was made. Figure 3, Figure 4, Figure 5 and Figure 6 show the results. 

DHW consumption appears as the second highest energy consumer, 34% of the total. If we look at DHW demand and losses, only 33% is due to heating hot water, the remaining 67% are losses, of which 44% are due to recirculation, 18% due to individual pipes, and a 5% for storage. The total predicted final energy consumption for DHW is 1,764 kWh, an average of 147 kWh/month. 

Figure 3: Useful energy demands, final energy consuption and costs, by category, calculated with PHPP
Figure 4: Final energy consumption by category and energy costs, calculated with PHPP
Figure 5: DHW demand and losses, calculated with PHPP
Figura 6: DHW demand and losses, calculated with PHPP

System

The system incorporates a PV array with 12 polycrystalline modules and a peak power of 3.18 kWp (Figure 7), and a 3 kW inverter. The main hot water generator is a 6 kW ait-to-water heat pump (wich also supplies heating and cooling, with a 500-liter DHW tank and 3-kW electrical immersion heater (Figure 8). DHW production is isntantaneous. When the sun is shining and there is more PV generation than electrical consumption in the home, a control system diverts the electrical energy from the PV panels that cannot be self-consumed into thermal energy in the DHW tank for use in the afternoon or evening (Figure 9).

Figure 7: 3,18 kWp roof-mounted PV array
Figure 8: DHW
Figure 9: Control system

This is particularly interesting in the summer in passive houses in warm climates with active cooling and only one heat pump, as it generally allows the heat pump to keep itself in cooling mode, rather than stopping, reversing and going into hot water heating mode, before reverting back to cooling (for example, when occupants return home in the afternoon and shower etc). The hysteresis in this process can mean the home is without active cooling during 2/3 hours, which can be a problem in comfort terms. The control system monitors the home’s electricity consumption and PV production, sending surplus electricity to the resistance in the DHW tank. The power of the resistance heater is modulated through a voltage regulator, due to the fact that the output power of the photovoltaic generator varies continuously according to the level of solar radiation, and that the available surplus depends on the transient electricity consumption of the house. 

Monitoring data & conclusions

Monitoring data for 2018-2019 shows a total of 1211 kWh of PV production was diverted to the electrical resistance in the DHW tank, with a peak water temperature of 58 ºC. PHPP calculations projected that DHW consumption was 1764 kWh. Logically, not all of the PV energy diverted to the DHW tank is useful, as it depends on when DHW consumption takes place. Nonetheless, the system shows that solar PV top-up is effective for assisting in hot water generation, thereby reducing net energy consumption derived from hot water use, shown in (Figure 10) and (Figure 11) below.

Figure 10: Monitored data showing PV generation, solar PV DHW production, and total energy consumption, 1-8 June 2019
Figure 11: Monitored data showing PV generation, solar PV DHW production, and total energy consumption, 5 June 2019

Bibliography

[1] Feist W., Peper S., 2015, “Energy efficiency of the Passive House Standard: Expectations confirmed by measurements in practice”. Passive House Institute Dr. Wolfgang Feist, Rheinstraße 44/46, 64283 Darmstadt, Alemania.

[2] Grant N., Clarke A., 2010, “The importance of hot water system design in the Passivhaus”. Elemental Solutions, Withy Cottage, Little Hill, Orcop, Hereford, HR2 8SE, Reino Unido.

[3] Parlamento Europeo, 2010, “DIRECTIVA 2010/31/UE DEL PARLAMENTO EUROPEO Y DEL CONSEJO, de 19 de mayo de 2010 relativa a la eficiencia energética de los edificiosb(refundición)”.

Massies de Mollet Nursing Home

Description Passivhaus design and consultancy for an elderly people’s residency located in Mollet del Vallès. This 6575 m2 building, designed by Genars and developed by FIATC Seguros via FIATC Residencias (Inverfiatc), is in the process of Passivhaus Classic certification. Praxis has delivered the PHPP modelling, design of the thermal envelope and airtight layer, advice on …

Praxis cabecera proyecto

Passivhaus

Massies de Mollet Nursing Home

Description

Passivhaus design and consultancy for an elderly people’s residency located in Mollet del Vallès. This 6575 m2 building, designed by Genars and developed by FIATC Seguros via FIATC Residencias (Inverfiatc), is in the process of Passivhaus Classic certification.

Praxis has delivered the PHPP modelling, design of the thermal envelope and airtight layer, advice on low-impact materials, and analysis and optimisation of thermal bridges and construction details.

We’ve also undertaken a thermodynamic and daylighting study of the building, using DesignBuilder (EnergyPlus & Radiance), to assess natural light levels and analyse the risk of summer overheating.

Our work has also included an audit of the mechanical and electrical systems, with proposals for improvements and compliance with the Passivhaus standard, to ensure efficient operation and low maintenance costs. Praxis has also undertaken the Blower Door testing and on-site Passivhaus supervision and quality control.

Year: 2021

Location: Mollet del Vallès, Barcelona

Services:
Passivhaus consultancy, thermodynamic simulation, daylighting analysis, M & E consultancy, Blower Door testing

Dynamic hygrothermal simulation and full-scale validation of a structural insulated panel made from bio-based materials.

Given the environmental impact of the construction sector- responsible for 40% of the total primary energy consumption of the European Union- reducing both the embodied energy of materials at manufacturing stage and minimising operational energy consumption in buildings are urgent tasks.

Dynamic hygrothermal simulation and full-scale validation of a structural insulated panel made from bio-based materials.

Given the environmental impact of the construction sector- responsible for 40% of the total primary energy consumption of the European Union- reducing both the embodied energy of materials at manufacturing stage and minimising operational energy consumption in buildings are urgent tasks. Timber, agricultural residues, and bio-based materials are local renewable resources that can be transformed into buildings products and components, fomenting the creation of circular economies, and reducing the environmental impact of the sector. The objective of the European ISOBIO project, that ran from 2015 to 2019, financed under the Horizon2020 program, was to address these problems through the development of new insulating materials and renders from plant fibres, agricultural residues, and bio-based binders. The article presents the results of dynamic hygrothermal simulations and full-scale validation of a structural insulated panel made from bio-based materials, for use in the construction of nearly-zero energy buildings.

ISOBIO structural insulated panel for new buildings

The prototype panel measured 1.95m x 1.95m, with a total thickness of 33.2cm in 8 layers with 9 different materials (Figure 1). The panel was rendered external with 25mm of lime and hemp plaster, applied on a rigid 50mm hemp insulation board, mechanically fixed to a 145mm red pine timber structure, filled with hemp, cotton, and flax insulation, followed by a 12mm OSB 3 timber board. An airtight and dynamic vapour control membrane was fixed to the inner face of the OSB, followed by a 45mm service void, insulated between timber battens with hemp, cotton, and flax insulation. The battens were positioned at 90º in relation to the main structural joists to reduce the thermal bridging through the timber. The inner service void was lined with a 40mm thermo-compressed straw board, plastered on the inside with 15mm of composite clay-hemp plaster, applied in 3 layers.

Figure 1: ISOBIO panel section drawings and materials
Figure 2: Location and type of sensros installed in the panel
Figure 3: Panel installation at the HIVE demonstrator, Wroughton, UK

Test set-up

Figure 3 shows the installation of the panels in the demonstrator in Wroughton, UK. A monitoring system was installed, with a meteorological station recording external climate conditions: dry air temperature, relative humidity, solar radiation, wind speed, wind direction, rainfall, and barometric pressure. A temperature probe was installed on the outside of the panel, with a heat flow and temperature probe on the inner face, for measuring thermal transmittance in accordance with ISO 9869 [1]. In addition, temperature and relative humidity sensors were installed at 3 positions within the panel (Figure 2), to measure transient hygrothermal behaviour inside the panel and compare the results with dynamic hygrothermal simulations made with the WUFI Pro tool, following EN 15026 [2]. WUFI Pro 1D is a tool developed by the Fraunhofer Institute in Germany for assessing the hygrothermal performance of one-dimensional building envelope cross-sections, taking into account the moisture content of the materials, their transient hygrothermal performance, capillary transport and summer condensation, with hourly outdoor climate conditions. The software version used was WUFI Pro v. 6.2.1.2210

Data was measured at an interval of 5 minutes, from 24/02/2018 to 14/03/2018 in the HIVE demonstrator, UK, for a total 432 hours, or 18 days, with 5184 data points. The interior temperature was maintained at an average of 25.5 °C throughout the period, with the use of an electric convection heater.

Monitoring Results and Validation

Figure 4 shows a cross section of the modelled panel, with sensor locations. Figure 5 shows the WUFI model of the panel and corresponding sensor locations.

Figure 4: Cross section of panel and sensor locations
Figure 5: Cross section of WUFI model and sensor locations

Figure 6 shows measured and modelled temperature and RH at position 2 (between the CAVAC rigid insulation and Biofib Trio insulation). Temperature dynamics are well reflected in the model. RH dynamics are less well reflected.

Figure 6: Measured vs. modelled (WUFI) interstitial temperature and relative humidity, positin 2, ISOBIO new-build panel, HIVE demonstrator

Figure 7 shows the measured and modelled temperature at position 3 (between the Biofib Trio insulation and OSB board). Temperature dynamics are well reflected in the model, with RH less so. The model nonetheless shows very close alignment with measured results.

Figure 7: Measured vs. modelled (WUFI) interstitial temperature and relative humidity, position 3, ISOBIO new build panel, HIVE demonstrator

Figure 8 shows the measured and modelled temperature and RH at position 4 (between the Intello membrane and the Biofib Trio insulation). Temperature and RH dynamics are well reflected in the model.

Figure 8: Measured vs. modelled (WUFI) interstitial temperature and relative humidity, position 4, ISOBIO new-build panel, HIVE demonstrator

Figure 9 shows the measured average heat flow rate, compared with the WUFI modelled heat flow rate, showing very good agreement.

Figure 9: Measured vs. modelled (WUFI)average heat flow rate, ISOBIO new-build panel, HIVE demonstrator

Conclusion

The results of the measured and modelled temperature and RH show good correlation, with dynamic temperature variations accurately reflected in the model. The short-term variations in relative humidity are not reflected with the same precision in the WUFI modelling results, possibly due to the assumption that the equilibrium water content in the materials is instantaneous, where in reality, there is hysteresis [3]. The hourly measured and modelled thermal transmittance data show very good correlation, with a difference of only 4% over the monitoring period.

The results indicate that bio-based materials combined in a composite SIP panel of this type can offer predictable hygrothermal performance for use in nearly-zero energy buildings.

References

  • ISO 9869-1:2014 Thermal Insulation – Building elements – in-situ measurement of thermal resistance and thermal transmittance. (Aislamiento térmica – elementos constructivos – medición in-situ de la resistencia térmica y transmitancia térmica)
  • UNE-EN 15026:2007, Comportamiento higrotérmico de componentes de edificios y elementos constructivos. Evaluación de la transferencia de humedad mediante simulación numérica.(Ratificada por AENOR en junio de 2010.)
  • N. Reuge, F. Collet, S. Pretot, S. Moisette, M. Bart, O. Style, A. Shea, C. Lanos 2019, Hygrothermal transfers through a bio-based multilayered ISOBIO wall – Part I: Validation of a local kinetics model of sorption and simulations of the HIVE demonstrator. Laboratoire de Génie Civil et Génie Mécanique, Axe Ecomatériaux pour la construction, Université de Rennes, 3 rue du Clos Courtel, BP 90422, 35704 Rennes, France.