Description Passivhaus design and consultancy for a high-performance sports centre located at 2600 metres above sea level in El Pas de la Casa, Andorra. This 9000 m2 building, designed by Engitec, is in the process of Passivhaus Classic certification. Praxis has done the PHPP energy modelling, design of the thermal envelope and airtight layer, advice …
Cramea, High performance sports centre
Passivhaus
Description
Passivhaus design and consultancy for a high-performance sports centre located at 2600 metres above sea level in El Pas de la Casa, Andorra. This 9000 m2 building, designed by Engitec, is in the process of Passivhaus Classic certification.
Praxis has done the PHPP energy 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 undertaken thermodynamic analysis of the building, using Design Builder (EnergyPlus), to assess thermal comfort and analyse the risk of summer overheating in critical zones in the building.
We have also consulted on mechanical and electrical system design, with proposals for improvements and compliance with the Passivhaus standard, to ensure efficient operation and low maintenance costs. Finally, we have provided with on-site Passivhaus supervision and quality control.
Year: 2022
Location: El Pas de la Casa, Andorra
Services Passivhaus design & consultancy, thermodynamic simulation, M & E consultancy, and site supervision
Radon gas is a naturally occurring radioactive gas that can enter buildings. It is currently the second most predominant cause of lung cancer after tobacco.
Radon gas: invisible and lethal. What is it and how to prevent it?
Radon gas is a naturally occurring radioactive gas that can enter buildings. It is currently the second most predominant cause of lung cancer after tobacco. It’s colorless, tasteless and has no smell, and is produced from the natural radioactive decay of uranium, present in many types of soils and rocks.
Becquerels (Bq) is the measurement of radioactivity. A becquerel corresponds to the transformation or decay of 1 atomic nucleus per second. In the air, radon concentration is measured by the number of transformations per second in one cubic meter of air (Bq/m3).
The national annual average reference level, set out by WHO in its “WHO Handbook on Indoor Radon: A Public Health Perspective”, is 100 Bq/m3. If this level cannot be reached due to country-specific conditions, the level should not exceed 300 Bq/m3.
Radon measuring devices are divided between passive and active detectors, with an uncertainty range of between 8% and 25%, depending on the type of device. The most common devices are usually passive, logically cheaper than active ones, and incorporate trace sensors for alpha particles, or ion electret chambers, to measure radon concentration.
As the concentration of the gas in indoor air can increase significantly in the short term (hours), is recommended to take long-term measurements (for example, 3 months). If the building has a ventilation or HVAC system, it is convenient to take measurements with the system on and off, in both cases for a long period time.
There are low-cost types of equipment such as the RadonEye RD200, or Airthings Wave, shown in Figure 2 and Figure 3.
Figure 2: RadonEye RD200, low-cost radon gas meter [Source: Radonova]
Figure 3: Airthings Wave, low-cost radon gas meter [Source: Airthings]
Radon gas and the Spanish building regulations
In 2019, and for the first time, Spanish building regulations established the scope and requirement of radon gas with a reference level for the average annual radon concentration inside habitable premises of 300 Bq/m3 (triple of what is recommended by the WHO).
Applicable to all new buildings, extensions, changes of use, or refurbishment of existing buildings, the regulations require the following measures, according to the risk area:
Level 1:
Radon barrier between living spaces and the ground
Ventilated air gap between the living spaces and the ground
Level 2:
Radon barrier between living spaces and the ground
Additional protection system:
Ventilated air gap between the living spaces and the ground
Ground depressurization system that allows the gas to dissipate from the ground.
The radon gas map of Spain according to the HS6 level 1 and 2 classification is shown in Figure 4.
How does radon gas enter a building and how to avoid it?
Radon enters a building through the fissures and openings in the envelope, especially in parts of the building in contact with the ground (slabs, basement walls, etc.), where the concentration of the gas is generally higher on the floors above (ground and first floor, etc). This is accentuated in the building during the heating period, where warm air rises, and the stack effect creates air infiltration of air on the lower floors (and exfiltration on the upper floors).
Radon gas entry is reduced and/or eliminated by a gas-resistant membranes, with a diffusion coefficient against radon less than 10-11 m2/s. An example is shown in Figure 5. The barrier must be continuous, taped and sealed at all joints and service penetrations. It is advisable to conduct a Blower Door test during the construction phase to detect leaks and repair them.
In Level 1 areas, as an alternative, it is possible to build a ventilated crawl space between the living areas and the ground, although it is a less safe solution than a radon barrier.
In Level 2 areas, the radon barrier is essential, along with a ventilated crawl space or a ground depressurization system.
The ground depressurization system consists of installing a network of perforated intake ducts, with mechanical extractors that conduct the air to the outside, above the building. This system has the same drawbacks as the ventilated crawl space and depends on a mechanical system.
Figure 5: Radon gas resistant membrane, Ampack Sisalex 871
Although few epidemiological studies have been conducted on the possible link between radon gas in drinking water and the incidence of stomach cancer, a study by Kyle P Messier and Marc L Serre of the University of North Carolina, USA indicates that increases the risk of stomach cancer. Therefore, water becomes a double entry route, by ingestion of contaminated water or by breathing radon gas evaporated from drinking water. Under normal circumstances, the amount of radon inhaled when breathing is greater than that ingested when drinking.
Radon in drinking water can be reduced and/or eliminated by employing granular activated carbon filters, but the filter itself can accumulate radioactivity and should be located outside the thermal envelope (in a garage, for example), taking care of its treatment as toxic waste at the end of its useful life.
Study of the incidence of radon gas in 122 homes in Ireland
Barry Mc Carron, Xianhai Meng, and Shane Colclough conducted a radon gas measurement study on 122 homes in Ireland, 97 Passivhaus-certified homes, and 25 conventional homes (reference). The results can be seen in Figure 6. The average level of radon gas inside the Passivhaus dwellings was below 40 Bq/m3, both on the ground and first floors. However, in conventional homes, the average level was 104 Bq/m3 on the lower floor, and 69 Bq/m3 on the first floor.
The differences clearly show the effectiveness of airtight construction to prevent the entry of radon gas: one of the requirements of the Passivhaus certification is to have a level of air infiltrations n50 ≤ 0.60, verified by an air-tightness test.
But not only this, Passivhaus homes have a mechanical ventilation system with heat recovery, which constantly renews the air, eliminating stale and polluted air, and introducing fresh and filtered air. This can be seen in the graph in Figure 7, where Professor Walter Reinhold Uhlig of the HTW University of Dresden, measured radon gas in a Passivhaus dwelling with a mechanical ventilation system on and off. With the ventilation turned off, in certain rooms the radon level increased to 350 Bq/m3, having remained below 100 Bq/n3 with the ventilation working.
Figure 6: Radon gas measurement results in 122 homes in Ireland [Source: McCarron et al 2020]
Figure 7: Measurement of radon gas concentration in a Passivhaus dwelling, with and without controlled ventilation [Source: Prof. Walter Reinhold Uhlig]
Considering how lethal it is, radon gas has- surprisingly- gone unnoticed among many professionals in the sector, public administrations, and health professionals. Thanks to increased awareness and the update of the Spanish building regulations, it’s an issue we clearly can’t ignore: we need to prevent radon from entering our buildings, and ensure correct ventilation! The empirical results shown above indicate that an air or radon gas barrier, together with a mechanical ventilation system, is a highly effective combination to reduce the entry of radon gas into a building and thus protect the health of users.
Description Passivhaus Component certification of the Hormipresa Arctic Wall construction system: a fully industrialized, high thermal inertia solution with an exterior white concrete finish. It has been certified as a Passivhaus component for the warm-temperate climate zone. To reach the Passivhaus Component certification Praxis undertook three-dimensional simulations of the wall to determine the thermal effect …
Passivhaus Component certification of the HormipresaArctic Wall construction system: a fully industrialized, high thermal inertia solution with an exterior white concrete finish. It has been certified as a Passivhaus component for the warm-temperate climate zone.
To reach the Passivhaus Component certification Praxis undertook three-dimensional simulations of the wall to determine the thermal effect of the steel connections penetrating the insulation layer using Dartwim Mold Pro 3D and Flixo Pro finite element simulation packages.
We calculated and optimised 10 standardised construction details, as required by the certification, associated with wall, roof, and floor connection details, and window installations. Praxis managed the certification process with the Passivhaus Institut.
The certification criteria for warm-temperate climate requires a Uwall ≤ 0.25 W/m2·K and all construction details must be thermal bridge free with Ψ ≤ 0.01 W/m·K.
Project Description PHI Low Energy Demand Certification for a detached single-family house in Gijón, Asturias, designed by architect Juan Ignacio Corominas. The house consists of 184 m2 distributed in a first floor and a semi-basement floor. The construction is mixed, combining rectified thermo-clay walls with SATE insulation and a wooden structure roof with 28cm of …
Casa Pasiva B en Gijón
Passivhaus
Project Description
PHI Low Energy Demand Certification for a detached single-family house in Gijón, Asturias, designed by architect Juan Ignacio Corominas.
The house consists of 184 m2 distributed in a first floor and a semi-basement floor. The construction is mixed, combining rectified thermo-clay walls with SATE insulation and a wooden structure roof with 28cm of thermal insulation. The carpentry is Cortizo COR 80 aluminum with Passivhaus component certification.
In the audit, Praxis verifies all calculation and design documents submitted by the Passivhaus Consultant, including architectural and installation plans and reports, PHPP calculation, Blower Door test report, ventilation commissioning, work monitoring and photographs.
Description PHI Low Energy Building 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 …
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 audited 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.
Description Passivhaus design and consultancy for 3 detached single-family certified Passive Houses in San Josep de Sa Talaia, Ibiza, designed by Mixis Arquitectos and executed by Avante. Project Management and construction management was undertaken by Martínez-Gil. Each home has a treated floor area of 270 m2, over 2 floors with a heated basement, achieving Passivhaus …
3 single-family Passive Houses in Ibiza
Passivhaus
Description
Passivhaus design and consultancy for 3 detached single-family certified Passive Houses in San Josep de Sa Talaia, Ibiza, designed by Mixis Arquitectos and executed by Avante. Project Management and construction management was undertaken by Martínez-Gil. Each home has a treated floor area of 270 m2, over 2 floors with a heated basement, achieving Passivhaus Classic certification.
Praxis did the Passivhaus design and energy modelling with PHPP, design of the thermal and airtight envelope, advice on low environmental impact materials, optimization of construction details and calculation of thermal bridges.
Our work focused on implementing passive design strategies to reduce summer overheating.
Year: 2021
Location: Sant Josep de Sa Talaia, Balearic Islands
Description Passivhaus design and consultancy and M & E engineering for two Passivhaus prototypes of Casas al Gusto, by Growing Buildings These two types of detached single-family homes are designed by the architect Iván Perez, from Territori 24. The homes, with treated floor areas of 125 and 225 m2, have 1 and 2 floors and …
Casas al gusto: Passivhaus prototypes
Passivhaus, M & E engineering
Description
Passivhaus design and consultancy and M & E engineering for two Passivhaus prototypes of Casas al Gusto, by Growing Buildings
These two types of detached single-family homes are designed by the architect Iván Perez, from Territori 24. The homes, with treated floor areas of 125 and 225 m2, have 1 and 2 floors and are designed to meet the Passivhaus Classic standard.
Praxis has undertaken the energy simulation with PHPP, the design of the thermal and airtight envelope, advice on low environmental impact materials, optimization of construction details and calculation of thermal bridges.
We have 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 solar PV energy production.
Description Energy consultancy for a multi-family building in El Carmel, a neighbourhood in the north of Barcelona, designed by Vora Arquitectura studio. This 544 m2 building, has a ground floor and 6 upper floors, on a sloped site in Mount Carmel. Each floor has one or two apartments, with a total of 7 units. Praxis …
Multi-family building in El Carmel
Energy consultancy
Description
Energy consultancy for a multi-family building in El Carmel, a neighbourhood in the north of Barcelona, designed by Vora Arquitectura studio.
This 544 m2 building, has a ground floor and 6 upper floors, on a sloped site in Mount Carmel. Each floor has one or two apartments, with a total of 7 units.
Praxis has delivered the thermodynamic simulation in Design Builder (EnergyPlus), focusing on the analysis and optimization of passive systems: analysis of solar gains, optimization of thermal insulation and bioclimatic buffer zone balcony spaces. The modelling helped us deliver the thermal and airtight envelope specification, window and shading systems specification, including a study of the impact of heat recovery in the ventilation system on energy demands.
Praxis also undertook an embodied energy study, comparing the carbon footprint and costs of different construction assemblies for external walls, with the aim of choosing an economically viable, energy efficient and sustainable solution.
The article presents an active cooling system using the supply air of the ventilation system with radiant ceiling panels, installed in a multi-residential building in the historic center of Girona, certified Passivhaus EnerPHit – Demand method.
Freshen up: active cooling with radiant ceilings in a Passivhaus retrofit
The article presents an active cooling system using the supply air of the ventilation system with radiant ceiling panels, installed in a multi-residential building in the historic center of Girona, certified Passivhaus EnerPHit – Demand method.
For each apartment, the system consists of an air-source heat pump, a mechanical ventilation unit with heat and moisture recovery (MVHR), a coiling coil on the supply air stream, and radiant ceiling panels. Control is carried out with a home automation system, with temperature and humidity sensors in each room. The solution offers both heating and cooling, working quietly and at low temperature, providing high thermal comfort and efficient performance when used with a heat pump. Reliable performance depends on correct system sizing, proper commissioning of the control system and of ventilation flow rates, and user maintenance and replacement of filters in the MVHR units. Systems such as this are not a good solution in homes where windows are open a lot on the summer and are better suited to warm and dry climates with lower levels of humidity.
The building is a multi-residential 6-storey building in the historic center of Girona, certified by Passivhaus EnerPHit – Demand method [Figure 1]. This private initiative – which was the first of its kind in Catalonia – put 4 new apartments of 129 m2 and a duplex of 162 m2 on the market.
Due to local heritage building regulations, insulation had to be installed inside, with some loss of thermal inertia. Active cooling using a cooling coil on the the ventilation supply air is a relatively simple concept which can be cost effective to install. However, thermal power can be limited when temperatures peak. The system presented here combines supply air cooling with radiant ceiling panels, to provide sufficient power to cover peak cooling loads.
PHPP, Passivhaus design: Oliver Style, Bega Clavero
Passivhaus Certification: Energiehaus Arquitectos
Description and operation of the system
Given space and floor-to-ceiling height limitations, 2 cooling systems were initially considered:
Ventilation supply air cooling only
Ventilation supply air cooling + radiant ceiling panels
The second option was chosen, given that operative temperatures in the summer could not be maintained at ≤ 25ºC using ventilation supply air cooling only. With 19 m2 of radiant ceiling panels (covering around 15% of the ceiling surface area), peak cooling loads could be met, calculated for an outdoor air temperature of 34.1 ºC, with an absolute humidity = 10,5 g/kg [1].
For each apartment, the system included the following equipment:
Radiant ceiling panels: Zehnder NIC 150 & NIC 300 [Figure 5]
Control system:
1 temperature & humidity sensor per room
1 Loxone mini server [Figure 7]
Various elements providing on/off control of the heat pump, 3-stepped control of the ventilation flow rate, and on/off control of each radiant ceiling circuit and control of water supply temperature to the radiant ceiling panels with a 3-way valve
Figure 2: Monobloc air-to-water heat pump
Figure 3: Energy recovery unit
Figure 4: Coiling coil, silencer, and supply air ducts (prior to insulation of ducts)
Figure 5: Radiant ceiling panels, prior to fixing on non-radiant panels
Figure 6: Infrared image of radiant ceiling panels
Figure 7: Control system switchboard
In heating mode, the heat pump generates hot water, circulating it through the radiant ceiling panels at a supply/return temperature of 45 ºC / 40 ºC. At the same time, the coil on the ventilation supply air stream heats the air to around 40ºC. The fan speed is controlled to avoid excessively high flow rates, and which can lead to low relative humidity of indoor air.
In cooling mode, the heat pump generates cold water, circulating it through the radiant ceiling panels at a supply/return temperature of 7 ºC / 12 ºC. At the same time, the coil on the ventilation supply air stream cools air to around 15 ºC. The coil also provides some dehumidification of the supply air, lowering the ambient indoor air dew point temperature and preventing condensation on the ceiling panels. In cooling mode, controlling the temperature of rooms individually is not possible given that the cooling coil only works for the entire apartment.
The heat and moisture recovery ventilation unit also helps to increase the relative humidity of the indoor air in winter and decrease it in summer, improving thermal comfort and reducing the dehumidification load that the cooling coil needs to overcome.
With the ventilation flow rate of 0.4 ach (135 m3/h), radiant ceiling panels typically cover – for both heating and cooling – approximately 65% of thermal loads. The ventilation system with the heating/cooling coil covers the remaining 35%.
Radiant cooling systems must have a robust control system, to avoid problems of surface condensation. Temperature and humidity sensors were therefore installed in each of the 5 rooms where the radiant panels were located (dining room, kitchen and 3 bedrooms). The water temperature of the panels is adjusted with a 3-way mixing valve, based on the temperature and humidity data from the sensors in each room, ensuring the panel surface temperature remains above the dewpoint, avoiding condensation.
The control system also modulates the ventilation unit’s fan power, lowering or raising the flow rate depending on the temperature setpoint and dehumidification needs. A schedule prevents the fan from operating as full flow at night, to avoid noise problems. If maximum power is required at night this can be a problem. The control allows you to set different setpoint temperatures according to specific schedules or occupancy rates, for each day of the week.
In its default setting, the ventilation system works automatically with pre-established schedules (with the possibility of manual adjustment by occupants). Figure 8 summarizes its operation:
Figure 8: Ventilation speeds and schedules
Conclusions
Cooling with radiant ceilings can offer an efficient solution that adds power to ventilation supply air cooling systems in Passive Houses in the summer. As the system is predominantly radiant and running at low temperature, it provides good comfort and can be more efficient than convective systems. Ceiling panels can be sized to meet heating and cooling loads, which in residential buildings retrofitted to Passivhaus standard means a coverage of between 15% to 30% of the ceiling surface area. This replaces ducted fan-coil or split systems, which take up more space in suspended ceilings, often a limitation in retrofit.
The control system presented here offers a flexible solution at a reasonable cost, with a relatively user-friendly interface. The possibility of visualizing and monitoring data remotely and in real time, facilitates the optimization of the system and helps in terms of preventive maintenance.
Systems such as this are not a good solution in homes where windows are open a lot on the summer and are more suitable for use in hot dry areas, since, in areas of high humidity, the power of the system will be limited depending on the humidity level of the indoor air and the proximity to the dew point. Robust operation depends correct system sizing, proper commissioning of the control system and of ventilation flow rates, and user maintenance and replacement of filters in the MVHR units.
Passivhaus design and consultancy, for this single-family house in Abrera, Barcelona, designed by architecture firm OMB Arquitectura and built by House Habitat.
LILU´s house: bio-based Passivhaus
Passivhaus, Blower Door
Description
Passivhaus design and consultancy, for this single-family house in Abrera, Barcelona, designed by architecture firm OMB Arquitectura and built by House Habitat.
The home has 143 m2 distributed over 2 floors, it will be the headquarters of the company House Habitat and a research unit for companies and universities. It is in the process of Passivhaus Plus certification.
Praxis has delivered the PHPP modelling, design of the thermal envelope and airtight layer, advice on low-impact materials, analysis and optimization of thermal bridges and construction details, and dynamic hygrothermal analysis of risk from moisture damage with the WUFI tool.
Praxis has also undertaken the Blower Door testing and on-site Passivhaus supervision and quality control.
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