HRS have worked on a number of Passivhaus schemes, so have extensive practical and technical experience. A Passivhaus project and an award winning building that HRS were heavily involved in is the prestigious Passivhaus Interserve Offices in Leicester.
The HRS Passivhaus air testing consultancy service will ensure you get the right advice at the right stage to achieve the Passivhaus standard. It is crucial if you are working to the Passivhaus standard that you contact HRS early – it never to soon to contact us.
- Good levels of insulation with minimal thermal bridges
- Passive solar gains and internal heat sources
- Excellent level of airtightness
- Good indoor air quality, provided by a whole house mechanical ventilation system with highly efficient heat recovery
There are no strict requirements with respect to domestic hot water, lighting and appliance consumption. The standard imposes an overall limit on the Primary Energy consumption which promotes energy efficiency in all of these areas.
|Energy performance targets and air changes per hour|
|Specific Heating Demand||≤ 15 kWh/m². yr|
|Specific Cooling Demand||≤ 15 kWh/m². yr|
|Specific Heating Load||≤ 10 W/m²|
|Specific Primary Energy Demand||≤ 120 kWh/m². Yr|
|Air Changes Per Hour||≤ 0.6 @ n50|
It is possible to achieve the Passivhaus standard when refurbishing buildings, although this can be a lot more costly. The standard requires that the Primary Energy demand target is met in all cases, this figure must include the space heating, domestic hot water, lighting, fans and pumps and also all of the projected appliance consumption. In addition to the primary energy demand the standard permits that either the Specific Heating Demand or the Specific Heating Load must be met.
The following table illustrates the elemental backstop values which should not be exceeded in order for the Passivhaus certification criteria to be met.
|Design Component||Limiting value|
|Walls, Roof, Floor (U-values)*||≤0.15 (W/m²K)|
|Glazing unit||≤0.8 (W/m²K)|
|Installed glazing||≤0.85 (W/m²K)|
|Infiltration (ach-1)||≤0.6 @ n50|
|Thermal bridging (linear ψ value)||≤0.01 (W/mK)|
|MVHR coefficient (η HR)||≥0.75|
|Ventilation electric limit||0.45 Wh/m3|
|Appliances||High efficiency recommended|
|Lighting||High efficiency recommended|
|On site renewables||No requirement but SHW typical|
* please note opaque U-values are only recommended targets and are not critical to certification. The backstops above apply to moderate weather regions only, for warmer climates the performance values could be reduced. Please consult your building certifier for more information.
A refurbished building can be certified as a “Quality-Approved Passivhaus” if the certification criteria for Passivhaus are met when refurbishing a building – this is based on the same criteria as for new buildings. It can however be very difficult to achieve the Passivhaus standard for older buildings for various reasons.
If you are able to use Passivhaus technology for all relevant building components in your existing buildings, it will lead to substantial improvement in respect of thermal comfort, structural protection, cost-effectiveness and energy requirements.
The standards have slightly relaxed certification criteria, as indicated below:
|Specific Heat Demand||≤ 15 kWh/m².yr||≤ 25 kWh/m².yr|
|Primary Energy Demand||≤ 120 kWh/m².yr||≤ 120 kWh/m².yr *|
|Limiting Value||n50 ≤0.6-1||n50 ≤1.0-1|
* PE ≤ 120 kWh/m².yr + ((SHD – 15 kWh/ m².yr) x1.2)
Thermal Bridging and Passivhaus
Thermal Bridging also exacerbates heat loss from buildings. In modern buildings that are well insulated and reasonably airtight, the thermal bridging losses can account for a significant percentage of total building heat loss.
Calculation of thermal bridging losses (psi values) can be calculated using thermal modelling software. HRS has dedicated experts to help analyse details, provide quantitative analysis and highlight potential solutions to meet required targets.
Thermal bridging analysis can assist with meeting Fabric Energy Efficiency targets for Building Regulations and also Code for Sustainable Homes ENE 02 criteria. Strict energy targets required for the Passivhaus standard may also require thermal modelling.
If you are unsure of the Air Tightness services you require please call 0800 030 4391 or email email@example.com and one of HRS Air Tightness Consultants would be happy to guide you through the process.
0800 030 4391
CASE STUDY: Centre For Medicine, University of Leicester. BREEAM, Thermography, Air Tightness Consultancy & Testing to Entire Building and Floor Plenums – pdf »
“Just wanted to drop an email show appreciation for HRS operatives for the works that they carried out. They very knowledgeable and were able to guide and work with our site team, in order to achieve satisfactory air tests.”
“Please pass on my thanks to the air tester for there positive approach and his hands on attitude. Can you please also pass this on to his line manager in his professional attitude. I look forward to being able to use HRS again in the future.”
“I would like to thank your air tester for his patience during the past tests. He has given me excellent advise which we help on future projects.”
Case Studies & Gallery
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HRS can provide you with a complete range of building environmental and sustainability services, meaning you can save time and money, avoid inconvenience and your risks are minimised.
From concept design stage to completion, HRS can work alongside you every step of the way. You and your project would be supported by HRS’s extensive knowledge that has been built up over 30 years, whether you need consultancy or on site advice and guidance, HRS’s large team of consultants and on site technicians are here to support you to make sure that your project hands over on time and within budget.
At HRS we believe strongly in being pro-active and customer focused, providing you with innovative cost-effective solutions.
All you need to do is make one phone call to 0800 030 4391 or email: firstname.lastname@example.org sending one set of drawings stating what services you require, and HRS will take it from there.
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