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Here at Encon we offer a full turnkey service when building or renovating your home, that is all aspects of the building from the structural requirements, energy efficiency and performance specification, implementation, complete construction of the house and completion or management of various tradespeople required to deliver all fit-out works, so all you have to do is move in and call your new house a home.
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Design & Build Homes
What is a Passive House?
A passive house is an energy efficient building designed to help reduce its heating needs and energy demand, therefore reducing its overall impact on the environment. When planning to design and build a passive house there are certain standards that must be met regarding heating, cooling, air leakage and total energy consumption. Houses are designed to meet passive house standards with the use of specialised software during the design phase called Passive House Planning Software, or PHPP. PHPP software allows designers to run computer simulations to ensure their design meets passive house specifications before the works begin.
What are the Passive House Standards?
To be certified as a passive house a building must meet certain standards as set by the Passive House Institute:
- Space heating demand must be ≤ 15 kWh/(m²a) per annum, or 10 W/m² for heating load
- Total cooling demand ≤ 15 kWh/(m²a) + 0.3 W(m²aK) – DDH
- Total primary energy consumption for hot water, heating and electricity ≤ 120 kWh/m²
- Air leakage ≤ 0.6 x house volume per hour
While these standards aren’t legal requirements when building a home, they are required should you wish to receive Passive House Certification from the Passive House Institute. If passive house standards are met conventional heating methods are not required such as boilers, radiators and open fireplaces.
What are the Passive House Standards?
To be certified as a passive house a building must meet certain standards as set by the Passive House Institute:
- Space heating demand must be ≤ 15 kWh/(m²a) per annum, or 10 W/m² for heating load
- Total cooling demand ≤ 15 kWh/(m²a) + 0.3 W(m²aK) – DDH
- Total primary energy consumption for hot water, heating and electricity ≤ 120 kWh/m²
- Air leakage ≤ 0.6 x house volume per hour
While these standards aren’t legal requirements when building a home, they are required should you wish to receive Passive House Certification from the Passive House Institute. If passive house standards are met conventional heating methods are not required such as boilers, radiators and open fireplaces.
Passive House Insulation Requirements
Insulation plays a key role in the design and build of passive houses. Typically, additional insulation is required than what would be found in a house built to typical building regulations. Insulation is used to reduce the transfer of heat through the building’s walls, roof and floors. U-Values must be low and are typically within the range of 0.10 to 0.15 W/m²/K). A variety of insulation materials may be used, including expanded polystyrene (EPS). Thicker walls and insulation are usually required to achieve these lower U-Values.
Passive House Ventilation
In addition to insulation, ventilation plays a critical role in the energy efficiency of a passive house. A combination of passive natural ventilation systems and mechanical heat recovery ventilation systems can be used, dependent on the climate of the building’s surrounding environment. Passive houses are airtight. Without a ventilation system fresh air could not be exchanged leading to higher levels of CO² and airborne particles. While many passive house ventilation systems may be available, it’s important to choose one that is certified by the Passive House Institute and has a proven high efficiency in heat recovery. The benefits of a mechanical heat recovery ventilation system include extremely low energy use, high-quality indoor air and comfortable indoor temperatures that stay consistent throughout the year. An efficient back up system can be used in the event the mechanical ventilation system does not produce enough heat certain days of the year or the system fails and needs repairs.
Other Passive House Requirements
Insulation and ventilation are both important components in the design and build of a passive house, but there’s still much more to it. It’s important to maximise passive solar gain — meaning the sun is used as often as possible to heat the air and water the home consumes daily. Every window must have energy efficient glazing and the appliances must be energy efficient. In a well-designed passive house, the sun, appliances and occupants themselves usually produce enough heat to keep the indoor air temperature at a constant and comfortable level from room to room.
To maximise the potential the sun can have on a passive house it’s important that windows face south or due south whenever possible. Avoiding north-facing windows can help reduce heat loss, provide natural light during the day and conserve the energy that would be used for artificial lighting and heating. PHPP software is used to help reduce the risk of overheating during warm, sunny days and ensure that the building sits at the correct orientation. Thermal bridging should also be addressed to reduce heat loss from uninsulated areas of the home. This includes areas between joints, walls, floors and ceilings.
Designing and Building a Passive House in Ireland
When planning to design a new passive house or retrofit an existing structure, it’s important to work with a certified architect and contractor who understands the requirements of the project. The Sustainable Energy Authority of Ireland breaks the designing and building process down into eight steps:
- Client briefing
- Site visit
- Sketch design
- The initial evaluation of energy performance
- Design and specification
- Tender documents and drawings
- The works
- Testing
The client briefing is designed to outline the requirements of the project, whether it’s residential, commercial or a scheme for a local authority. A site visit is then carried out to determine the correct orientation for the structure and any obstructions in its surrounding environment. A sketch design is completed to the requirements of a passive house and an initial evaluation of energy performance is conducted using PHPP software. When everyone involved is satisfied with the performance of the initial design, a detailed design and specification is completed and retested with the PHPP software. Detailed design and specifications are required to apply for planning permission.
When permission has been granted technical drawings are required before construction can commence. These technical drawings include specifications on ways to minimise heat loss, ensuring airtightness, sizing ventilation equipment, back-up heating, solar panels and other required elements that aid in the efficiency of a passive house. The works can begin after a competent contractor has been found. Subcontractors may need to be utilised for the installation of ventilation equipment, solar systems, back-up heating systems and controls.
Testing should begin on the structure once the airtight layer is complete so problems can be rectified as they arise. Air-leakage cannot exceed 0.6 changes per hour using 50Pa over pressurisation and under pressurisation testing. The testing should only be conducted by an independent inspection and testing body.
Energy Efficiency
On average, Irish houses require 9,722 kWh of energy for space heating purposes per year, resulting in 2,855kg of CO² emitted into the atmosphere. A house meeting Passive house standard typically requires as little as 1,500 kWh of energy per year to meet space heating requirements. The reduction in energy demand results in a drastic cut to the carbon dioxide released into the environment to 176kg per year and a significant savings on energy bills. The heating cost for a 150m² house would be in the range of €100 per year should it meet passive house standards.
WHAT IS nZEB – Near Zero Energy Building?
Meet & Exceed Ireland’s New Building Regulations
U-values measure the effectiveness of insulating materials. The lower the U-value, the less heat will be lost through a building element, like an external wall or the foundation of a house. Ireland’s Building Regulations Part L (Conservation of Fuel and Energy) have changed as of the 1st of November 2019.
These changes will lower the U-value requirements for many building elements. The new regulations and changes to (Part L 2019) are displayed below.
New Buildings – Part L 2019
Building Element | Minimum U-Value |
Ground Floor (No Underfloor Heating) | 0.18W/m²K |
Ground Floor (Underfloor Heating) | 0.15W/m²K |
External Walls | 0.18W/m²k |
Flat Roof | 0.20W/m²K |
Pitched Roof (Sloping Ceilings; Rafter Level) | 0.16W/m²K |
Cold Roof (Ceiling Level) | 0.16W/m²K |
Existing Buildings Part L 2019
Building Element | Minimum U-Value |
Ground Floor (No Underfloor Heating) | 0.45W/m²K |
Ground Floor (Underfloor Heating) | 0.15W/m²K |
External Walls (Cavity) | 0.55W/m²K** |
External Walls (Other – Not Cavity) | 0.35W/m²K |
Flat Roof | 0.25W/m²K |
Pitched Roof (Sloping Ceilings; Rafter Level) | 0.25W/m²K |
Cold Roof (Ceiling Level) | 0.16W/m²K |
External Doors, Windows, Roof lights & Curtain Walling | 1.40W/m²K |
Major Renovation and nZEB
The updated TGD Part L 2019 sets out requirements for dwellings that undergo major renovation. Major renovations are considered when more than 25% of the building’s surface area (the building envelope) undergoes refurbishment or renovation. The TGD states that the performance of entire building should be improved to a cost-optimal level where technically, functionally and economically feasible. The cost optimal performance level is considered 125 kWh/m²/yr when calculated in DEAP.
To calculate the surface area, the entire external envelope needs to be considered. This includes the external walls, floors, roof, windows, doors etc. TGD Part L 2019 defines the envelope as the surface area of the building “through which it can lose heat to the external environment or the ground, including all heat loss areas of walls, windows, floors and roof”.
To calculate the percentage that would trigger a major renovation, take the building element and divide by the total surface area (of the building fabric). For external walls, we would divide 150m2/386m², giving us a percentage of 39% of the surface area. This means external insulation or internal wall dry lining upgrades would be considered a major renovation as more than 25% of the surface area will undergo refurbishment. The cost optimal level of 125 kWh/m²/yr requirement means that this dwelling would need to achieve an equivalent BER rating of B3 where it is technically, functionally and economically feasible to meet the updated requirements of Part L 2019 – Existing Buildings.
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What works are considered major renovations?
Major renovations include cladding the external surface of the wall or dry lining the internal surface of a wall. Painting, re-plastering, re-slating or re-tiling are not considered to be major renovations. In addition, attic insulation installed at ceiling level between the joists and installation of cavity wall insulation are not considered to be a “major renovation to the surface area”.
Part L does not consider it to be technically, functionally or economically feasible to bring the entire building to cost optimal level when replacing the surface area of roofs, floors or windows. In addition, historic buildings (of architectural or historical interest) should aim for improvements to the building that are “reasonably practical”, i.e. the works should not harm the character or increase risk of long-term deterioration of the building fabric or fittings.
Dwellings that are damaged due to natural disasters (floor, fire, etc.) or a material defect are also exempt as it is not considered economically feasible to bring these renovations to a cost optimal level.
Meeting Part L 2019 – New Build
For both new build and retrofit, Part L defines the requirements as buildings being designed and constructed to limit the amount of energy required for operation (energy performance) and its associated carbon emissions (CO2) as is reasonably practicable.
For new build this includes:
- Limiting the calculated primary energy consumption and related CO2 emissions as reasonably practicable using DEAP (Dwelling Energy Assessment Procedure). This tool is offered by the Sustainable Energy Authority of Ireland (SEAI).
- A significant percentage of the energy required comes from renewable energy sources, generated either on or off-site.
- Heat loss is limited, and heat gain is optimised through the building’s fabric.
- The use of highly efficient space and water heating systems, including the system’s controls and source. The use of oil or gas-fired boilers requires systems with at least 90% efficiency (seasonal).
- That all buildings are designed to avoid the need for cooling systems.
- Ensuring the owner/operator of the building understands all systems, maintenance requirements and is operated to use as little fuel as possible.
Meeting Part L 2019 – Existing Buildings
Meeting Part L 2019 for existing builds is much the same as new builds, however, includes the following additions:
- Controlling the output of space heating and hot water systems.
- Limiting heat loss from a variety of components including pipes, ducts and vessels used for storage or transport of hot water and air.
- Meeting the cost optimal level of energy performance when existing buildings undergo major renovation, as explained in further detail above.
Thermal Bridging
Care should be taken to avoid thermal bridging around common junctions, including windows, doors, wall openings, at junctions between elements to name a few. The DEAP methodology considers heat loss from thermal bridges when calculating energy use and CO2 emissions. In any case, thermal bridging should not pose a risk of either surface or interstitial condensation.
Insulated Concrete Formwork (ICF)
Why Choose ICF?
ICFs consist of high-density polystyrene panels 1200mm long, 400mm high, and 65mm wide, spaced apart by high strength polypropylene webs. The forms provide a fully insulating, permanent shuttering system into which concrete is poured.
Once cast, the solid concrete core not only provides the necessary structural integrity for the building, but also excellent sound insulation, fire safety, thermal mass and durability for the structure’s lifetime.
The polystyrene panels of each block provide the thermal insulation to the structure, with U-values between 0.24 W/m2K and 0.13 W/m2K being easily achievable.
The forms, being extremely light (only 3.5 kg each), are simple and easy to build, with all of the attendant handling and safety benefits. So, if you’re looking to construct bespoke new builds, then let ICF be the solution for your construction needs.
ICF for Architectural New Homes
Amvic ICF is the strongest insulating concrete formwork system on the market.
There are many benefits that ICF can bring to your architectural new homes project. Simplicity & convenience is just a few to mention.
The powerful combination of the patented, reversible FormLockT interlock, EPS composition, innovative web design and web spacing result in:
- A simple, strong formwork system that requires less support during installation giving straight, flat and plumb walls.
- Less wastage when compared against other ICF or building systems.
- The ability to withstand internal concrete vibration, ensuring a structurally superior wall.
- Increases speed of construction.
- Reduces labour costs.
- Provides the highest level of performance during and after construction.
Therefore, ICF is a must when it comes to any new project that relates to architectural new homes.
ICF walls can be finished internally by gypsum board screwed directly to the integral webs.
A wide range of external finishes may be used including brick, stone, timber cladding, and renders. ‘Through-coloured’ polymer renders are the most popular form of render finish, a wide variety of colours and textures being available.
As can be seen, ICF is indeed a very cost-efficient solution for bespoke new builds and architectural new homes. Contact us today to find out more information.