design + energy + excellence

Tag: Timber Frame

Isabel Explains the Concept and Materials of Project Net Zero Home

MEDITE SMARTPLY kindly shared with us the video they prepared featuring our Passive House in Crossabeg – Project Net Zero Home.

Project Net Zero Home is an exemplar new-build house project which aims to achieve Net Zero Carbon utilising MEDITE SMARTPLY products.

The project demonstrates how we can reduce both operational carbon and embodied carbon by using the right products and materials.

Passive House Concept

This house was guided by the Passive House standard, the world‘s leading standard in energy efficient construction. It embodies quality, comfort, and remarkable energy efficiency.

The Passive House – definition

Passive Houses maintain a consistent, comfortable temperature throughout the year with minimal energy usage. These structures achieve this by utilizing passive heating methods, optimizing sunlight exposure, leveraging internal heat sources, and employing heat recovery systems, often eliminating the need for traditional heating systems even in harsh winters.

Fabric First Approach

The technical design was focused on fabric efficiency and airtightness.

This project involved meticulous attention to detail in perfecting the building fabric and selecting materials. Each component, from insulation materials to walls, roofs, and floors, was carefully chosen to align with our sustainability goals. The focus was on optimizing energy efficiency as a means to reduce carbon emissions.

Materials

The Project Net Zero Home prioritized the use of wood as a construction material of the future, recognizing its ability to effectively sequester carbon. This included the use of timber products manufactured in Ireland from FSC® certified forests managed by Coillte (MEDITE SMARTPLY PROPASSIV system).

The project aimed to use materials with lower carbon intensities and lower transport-related carbon emissions. Other materials were used for their recyclability at the end of their lifecycle, their performance during use, and their long-term durability.

Airtight and Thermal Bridge Free Design

Airtightness is an important requirement for any energy-efficient building.

The SMARTPLY Propassiv board was instrumental in achieving outstanding airtightness results. Engineered with airtightness in mind, this board offers an integrated vapour barrier which eliminates the need for for additional AVCL (Air and Vapour Control Layer) membranes. It significantly simplifies and streamlines the construction process, enhancing the overall efficiency on site.

Attention to detail and having a construction team working together were also vital to achieve good air tightness results.

One of the main principles of a Passive House design is to achieve a thermal bridge free construction. Therefore, thermal bridges were carefully assessed when designing the thermal envelope, and some had to be assessed using 2D and 3D software.

Building Systems and Passive Systems

This project employed a range of advanced building systems, including the integration of renewable technologies, to ensure optimal performance and sustainability.

A combination of passive strategies, including strategically designed canopies and blinds, played a crucial role in enhancing energy efficiency and comfort. These elements were integrated to maximize shade during summer months, preventing overheating, while allowing ample sunlight in the winter, thereby reducing the need for active heating and cooling systems.


Energy Efficiency Evaluation

The air tightness test returned the impressive result of 0.19 air changes per hour. This is lower than any passive house currently in the Passive House database for Ireland.

The energy balance of the house design was tested using the Passive House Planning Package (PHPP). The Passive House energy threshold for heating is 15 kWh/(m²yr). The heating demand as calculated by the PHPP is 12.7 kWh/(m²yr) for this house.

The house achieved a Building Energy Rating (BER) of A1.


You can learn more details about this project here.


Advantages and Disadvantages of Timber Frame Construction

 

Advantages of Timber Frame Construction

 

  • Recyclable
  • Renewable

Timber is classified as a renewable material, as the principle holds that if a tree is felled another is planted in its place. As long as this balance is maintained, the supply will be sustainable.

  • Low embodied energy if constructed in local timber
  • Reduced construction waste through efficient controlled manufacturing
  • Low volume of waste on site requiring removal
  • Quick build time

A prefabricated timber frame can be erected on site faster than a comparable brick and block construction. However, timber frames may require additional time for their design and fabrication, which can lead to a longer wait before work begins on site. 

  • Reduced site labour
  • Reduced time to weather the structure
  • Earlier introduction of following trades

The quicker erection time enables interior trades such as plastering and electrical wiring to begin work earlier in the build programme, as the interior will be exposed to weather for less time.

  • Can be built to exceed 60-year design life
  • Energy efficient when constructed to current standards
  • Fast heating due to low thermal mass

Their low thermal mass allows spaces enclosed by timber frames to heat up more quickly than masonry construction, however they will also tend to cool more quickly.

  • Reduced time on site reduces environmental nuisance and disruption to local residents
  • Engineered product
  • Factory controlled quality assurance in fabrication

Off site fabrication can allow higher quality to be achieved.

  • Efficient use of material due to controlled engineering and fabrication
  • Reduced construction time translates into reduced risk exposure

 

Potential Problems with Timber Frame Construction

 

  • Traditional procurement process
  • Additional design and engineering time
  • Modification of general arrangement drawings if based on masonry construction
  • Lack of experienced builders and erection crews
  • Lack of experience of following trades
  • Transportation and carriage access
  • Exposure to weather before enclosed
  • Work of following trades
  • Deficiency of site quality control
  • Combustibility of timber requires vigilant quality control to achieve required fire rating of separating and compartment walls

The fire resistance of timber frame buildings is achieved by a combination of the lining material, the timber structure and the insulation.

Additional fire protection can be given to the frame by the boarding used to clad it and fire stops installed to prevent spread through the cavity.

Recent fire tests commissioned by the Timber Frame Industry and the ITFMA showed that in general a 15mm Type A plasterboard is required to meet the Fire resistance of REI 30 for external walls (see detail).

The risk of fire can be increased if timber frames are not erected correctly, and during construction prior to fire protection being installed.

  • Susceptibility to decay of timber when exposed to excessive moisture

Timber frame structures must include a vapour barrier between the lining of the inner wall and the insulation, to prevent vapour passing through.

  • Acoustics

Timber frame structures may not achieve the same level of sound insulation as concrete or masonry as they are not as dense.

 

Timber Frame – Wall Detail (Service Cavity Wall)