Trunk CLT provided a full design, engineering, and supply and erection service for this detached house in Hertfordshire. Trunk CLT is headed by Mike Jacob and Jim Johnstone. Mike is a Chartered Construction Manager, and Certified Passivhaus Tradesperson, director at Trunk low energy and has worked in the emerging low energy construction sector for many years. Jim is a CLT and solid timber construction industry specialist. Jim has extensive experience delivering groundbreaking bespoke one off and multi-storey timber projects in London, Nationwide and abroad. It’s a positive blend of technical, practical and project management skills which ensures real quality of construction  together with passivhaus standards.

With extensive forward planning at each junction Truck CLT have been able minimise the heat losses from both a an air tightness and thermal bridging point of view. The building has a complete CLT structure with 180mm to 160mm of Schneider Holz wood fibre insulation, The building fabric is secured with a range of airtight tapes and high performance membranes all supplied by Partel.  This level of detail is consuming but where these points can slow down the project they are critical towards achieving long term efficiency and a safe building fabric. Also Truck CLT always makes up for this in other areas like for instance the projects principle structure was erected in just two days, admirable to say the least!

Project build-up

• Highly insulated floor slab
• Fully constructed CLT core framework
• Internal Air tightness and vapour check layer DB90 from AMPACK
• Externally insulated by Schneider best wood fibre natural breathable insulation
• UV stable Monolithic TPU technology – Amapatop F Black from AMPACK
• Counter batten and beautifully finished with a cedar cladding

​It’s one of the nicer, and technically solid projects we’ve been involved in recently. It’s also fantastic to see how the finishes can be exactly as desired.

Erection of first floor CLT with combination of Ampacoll XT60 providing a permanent air tight seal and continuing that redline of Schneider Wood fibre insulation.

Both internal and external eye pleasing finishes.

WUFI Analysis of woodfibre insulation

WUFI analysis Woodfibre insulation

St James Hospital

These types of project are worth considering, not just because it is a hospital but because of the mixed solid wall construction and the challenges it brings.  There have been a number of research papers from noted academics over the past number of years which serve to highlight the issues, some of the myths and also to suggest actual solutions and guides. The most recent such paper is below from SDAR by Joseph Little and Benat Arregi in which they focus on a Dublin solid wall project where various measures are investigated and risks evaluated. 

Hygrothermal Risk Evaluation for the Retrofit of a Typical Solid-walled Dwelling

Another relevant paper is Historic Scotland paper 15 (By Joseph Little, Calina Ferraro & Beñat Arregi) in which various solutions are tested and analysed – this paper was particularly interesting as it highlights issues with what have become standard upgrade measures using vcls or ‘intelligent’ vcls. We have always had a particular issue with vcl’s in solid wall upgrades as it is rarely possible to have the installation to a a high enough level to avoid risk. We know technically its possible but we just haven’t seen it happen – floor junctions, services and real world issues just make it too difficult. Commercial conservation buildings also have higher humidity loads and as We like these papers as they use WUFI and dont rely on an outdated and risky assessment programme using the glazer method. (This method can have its uses but not for solid walls or flat roofs)

Technical Paper 15 – Assessing risks in insulation retrofits using hygrothermal software tools

If we take the existing solid wall – in a relatively poor condition and with areas exposed to driving rain this actually quickly rules out most types of insulation. Unless an independent consultant actually tests the wall using a Karsten tube, carries out Wufi analysis over 5-7 years using local climate data and with applicable PI insurance it is becoming clear that Calcium silicate insulation can be viewed as the most risk averse or safest solution.

Calcium silicate from Partel – Its the only ‘green light’ system in – graph from HS-15

We actually analysed this wall using WUFI with the following conclusion extracted from our formal report.

”It was interesting to note that in winter months the relative humidity increased to high 80% and will reach this figure annually for sustained periods. The highest recommended figures for Epatherm calcium silicate are actually much higher at 95%. This figure of 95% applies only if the system is fully bonded, capillary active, hygroscopic and alkaline. Equilibrium was reached 2-3 years in all cases with water content levels acceptable.

Existing wall

There is considerable safety in choosing the EPATHERM system featuring all system parts as the simulated outputs have relative humidity below the 95% threshold.

Installation of Epatherm

A horizontal DPC would normally be recommended in such historic retrofits. There is an EPATHERM system part that would be recommended to be installed. A Chemical is injected at ground floor level to ‘create’ the dpc in the normal location thus reducing risks of moisture loads from rising damp. The Horizontal DPC by Epasit is Epasit MSP. In this case due to the existing vented basement we are satisfied that this will not be necessary in this instance.

The installation of a breathable external brick seal – Natural product – would further improve the position – if desired the product is Epasit IP237”

Insulation Guide –EPATHERM GENERAL

1. Ensure existing Brick clean and dry and free of lose components. Use a Lime plaster (Epasit MPM1 or MPM 2) to level if required. Generally if brick in reasonable condition the system can be applied directly. Lime levelling coat is preferred in conservation projects. In is important that the wall be level before applying the system.
2. Prime all sides of EPATHERM® etp with Primary coat EPATHERM® etg Use approximately 0.7L per m2, allow to react for 45 minutes before the next stage. Freshly sawn edges must be re primed.
3. Apply board adhesive EPATHERM® etk with notched trowel, 4-5kg per sqm
4. Paste and fix Indoor climate board EPATHERM® etp as closely as possible – avoid joints repositioning light switches as necessary.Avoid cross joints keeping 200mm staggered joints. 1000mm * 750mm in 30 or 50mm thickness as standard (20-160mm available on demand 20mm reveal boards available or wedge boards for floor connections) If surface is smooth use plastic mushrooms to affix boards in addition to adhesive. In all cases above 3m us 5 plastic mushrooms per board.
5. Fill all joints and unevenness on the surface with EPATHERM® multi-eti also applying a base coat of plaster 4-5mm deep, 1-2kg per m2
6. Insert EPATHERM® etw Alkali – resistant glass fibre fabric reinforcement mesh into Multi-eti (5)
7. As the first layer dry’s apply a Finish coat of EPATHERM® multi-eti to desired finish.

The application is proposed as follows: -

1. EPATHERM® etk Board Adhesive
2. EPATHERM® etp Indoor climate board with Primed coat EPATHERM® etg
3. EPATHERM® multi-eti also applying a base coat with EPATHERM® etw Alkali – resistant glass fibre fabric
4. EPATHERM® multi-eti finish coat

Application

Unique system advantages

• Insulation and regulation of room air conditions
• Optimal fire protection
• No health risks – purely mineral composition
• High alkalinity prevents mould growth
• Easy and flexible application

Garden view

We were delighted to be contacted by Diarmaid Brophy Architects – A forward thinking architectural practice with obvious architectural talent but balanced with a good knowledge of how buildings work.

The project involves the full refurbishment of this Protected Structure – a mid-19th terrace single storey over basement property with a 2 storey return to the rear. While the property retained much original fabric, it was in a poor state and was fully refurbished to create a modern comfortable home, while retaining its authentic character.

LUNOS Silvento extract fan

Our task – working with the architectural team was to address the ventilation so that the indoor air quality would match that of the rest of the building. As the building is protected and of solid brick construction the exterior grills had to be sympathetic to the buildings character. This can be accommodated either through the provision of pre coloured grills or bespoke grills provided by the builder.

The builder in this project was Principal Construction – a heritage and grant listed contractor who brought things together onsite and actually installed the LUNOS system. 

Dooroge woods is a development of 37 luxury 3, 4 and 5 bedroom detached homes close to swords in Dublin. The aim of the developers was to deliver a high performance development that would deliver in terms of quality in all aspects, not just a A2 rated property.
Impressive airtightness was demanded and so Ramstown Timber frame were appointed together with the Ampack Airtightness range. Nicky Stafford of Ramstown timber frame is experienced in passive house building and airtightness and was an interesting choice have worked in ‘one off’ housing most recently.

The quality control procedure from passive house single dwellings is welcomed in multi-unit development and has seen the development meet or exceed the brief where airtightness is considered. 

Greyfield developments as modern developers are acutely aware of the air quality issues and are keen to continue to develop a long term reputation for high standards.

Accordingly we were brought in to present LUNOS decentralised ventilation systems. The issue of quality control with ducting installation and future cleaning was  a factor when LUNOS were appointed. 

The chosen LUNOS demand controlled ventilation system (DCMEV) operate on a completely decentralised system – Ducting is right through the wall via pressure controlled inlets and intelligent extracts that adjust automatically relative to time temperature and humidity. LUNOS fans have expected lifespans of over 30 years and can cost €5.00 per year to run for the overall system. With this system indoor air quality is assured for decades.

LUNOS Silvento smart extract fan

LUNOS Silvento complete

LUNOS ALDR fresh air inlet

Ampack Ampatex DB90

The building appears uncomplicated but achieving such clean lines, finishes and the hidden low energy precision requires a builder with an impressive skillset. Greentec Eco homes were selected and again delivered to the usual high standards.

A comment from Lenni Antonelli at passivehouseplus.ie sums up Lester Naughton and Niall Dolan of Greentec.

       I ask Naughton if hitting the passive house airtightness target of 0.6 air changes per hour was straightforward. “With this guy,” he says, pointing to builder Niall Dolan, “yeah, it was.” Dolan in turn praises the quality and detail of Naughton’s design drawings. 

We’d like to think the tapes and membranes from Ampack helped then along the way ! In this project Niall and Lester used Ampacks DB90 & DB2 membranes internally and externally Protecta and Aero. This essentially applies the market leading 10 year system warranty of Ampack to the high performance timberframe.

Pat Doran construction were chosen to upgrade this south Dublin residence. The project had been proposed as Enerphit but suggested additional costs had brought this into doubt before the involvement of Father and Son team Pat and Paul Doran. “We said it might be possible to do Enerphit without it costing more, “From our experience and knowledge we were able to say that the budget was sufficient, that the house had a good orientation and form factor for passive house” says Paul Doran.

Pat Doran construction specialise in Passive house, Enerphit and NZEB (NEZB) building and through experience and specialist training are offering real low energy building expertise at reasonable prices.

 Enerphit projects are more challenging as details must accommodate the existing building and find ways to sympathetically upgrade the junctions to appropriate levels. The importance of having either an experienced or extremely knowledgeable contractor and design team is important. This skillset enables cost effective solutions for these difficult junctions. Airtightness and thermal bridging detailing are often the most challenging issues.

An example of one such junction was the large steel posts which while internal were connected to the new foundation. Pat Doran construction opted to use compaCFoam to support the steel. compaCFoam is possibly the highest performing thermal isolation material with thermal conductivities as low as 0.038. It is available in different density classes from CF 100 to CF400. CF 100 is typically used for thresholds and CF400 for point loads. CF400 is shown in the above photo.

Just how strong is compaCFoam ? Its surprisingly so – there is a  Datasheet  here but to get a visual – you can build on it, drive on – pretty much whatever you need to do depending on the load and density class.

 Photos – from passivehouseplus.ie

A new timber frame construction was erected adjacent to the older cottage and within 20m of the sea - this challenging location has meant that superior building protection solutions were chosen to ensure long term building security.

The Ampack Airtight system was achieved to enerphit levels of airtightness and to manage vapour in the building. External and internal systems were supplied by Ampack care of Partel which essentially ensures the structure avails of the market leading 10 year warranty by Ampack  

Specialist insulation materials were also used to improve the performance. Cellulose insulation pumped at 65kg/m3 was used in the exterior timber frame walls with 100mm of Woodfibre insulation outside of this. The internal service cavity has 50mm flexible woodfibre insulation (both woodfibre and cellulose are used to keep the house cool in the summer).

Thermal bridging was addressed in all areas using Compacfoam underneath the timberframe and doors and the entire roof has woodfibre insulation over the rafters. Heico fixings were used throughout.

The LUNOS decentralised heat recovery ventilation system was chosen due to guaranteed low sound levels, ease of installation and low running costs. We also used the smart LUNOTHERM element.

Internally the soundproofing of floors used a combination the Idikell system from Ampack and 20mm of rigid high density woodfibre insulation.

The project has finished and the results in terms of location and comfort are exceptional.

(Airtightness, Thermal bridging, Windows and Insulation are all in keeping with many passive house projects recently undertaken but certification was not a requirement from the clients. Building performance and comfort were the primary factors)

Project management, specification and supervision by Corbwell Design. Low energy materials and specification by Partel. Original architectural design by others.

Located on the outskirts of a Berkshire village, the old water tower – now certified passive house – is that the home of Owner and co-founder of Gresford architects -Tom Gresford.

The property has been certified as a Passivhaus – a title granted to buildings that use natural strategies of heating and cooling, instead of counting on electrical systems.

Gresford Architects aimed to show that passivhais need not be what has become to be known as a typical passivhaus – instead providing a vernacular high quality modern design.

“We have aimed to create a house that is on the cutting edge of sustainable design, yet eschews the hair-shirt approach to sustainable living that many people think of when considering environmentally friendly homes,” Gresford Architects said.

“The house is conceived as a modern interpretation of the timber-framed barns of the area, that when seen from the distance reads as a simple, traditional, agricultural building,” they added. ”On closer inspection it reveals itself as a crisply designed, carefully made, contemporary interpretation of the historic buildings it draws inspiration from.”

The building is 2 storeys high, with a gabled roof and a facade of black-stained timber weatherboard.

Gresford with the able assistance of the services of the in demand Mike Jacob of Trunk Low energy opted to utilise a wide timber framed wall using a selection of Airtight tapes and membranes from Ampack. Ampack now offer BBA certified external and internal systems that complement their 30 years of real time experience in the field of airtightness.

The partnership for this project has recently evolved with the formation a new joint venture taking advantage of the strenghts of Trunk Low Energy and Gresford architects TGPassivhaus. Both parties have a history of delivering ultra low energy efficient homes, often using ecological materials.

Project Specifics

Architects: Gresford Architects Ltd

Certifier: Warm: Low Energy Building Practice

Building Society: Ecology Building Society

Project Management: Trunk Low Energy Building

Main Contractor: MBC Timber Frame

Specialist tapes and Membranes: Partel