Early-Stage Carbon Calculator

By Pine1 Posted in - Exterior Products & Interior Products & Black Pine Resources on August 30th, 2021

As part of the race to upgrade the building industry and lessen our carbon footprint, a new service is available that estimates your project’s expected carbon output.

This service is in the form of a carbon modelling tool, designed to calculate both the operational and embodied energy of your project. This feature sets it apart from other carbon calculators, enabling project owners and designers with solid numbers to work with and allows you to compare the effects of different products and materials.

This service is available at the early design stage of your project, enabling clearly informed decision making that will save time and money – before any carbon needs to be spent.

It should be especially noted how, in comparison, the extent of operational emissions dwarf embodied carbon emissions in buildings that just meet the building code.

The result of a code-minimum building is exceptional energy consumption for the duration of its lifespan, not even including the careless energy spent to construct it.

It is crucial to significantly decrease a building’s operational carbon emissions – which Passive House tools allow us to do.

Carbon Conscious Design Principles:

There are some design principles for reducing carbon emissions, which can be used for any project. These lower the operational emissions to the same level as embodied carbon, which is a huge feat.

To reduce embodied carbon, we’d need to:

Minimise the use of aluminium, steel and concrete – they have poor thermal performance, as opposed to timber.
Use FSC-Certified timber construction.
Prioritize selecting timber-frame windows, then uPVC, and lastly aluminium.
Use CO2 refrigerants for hot water heat pumps, and R32 refrigerants for heating and cooling – they have the lowest impact.
Reduce construction waste.

To reduce operational carbon, we’d need to:

Increase your building’s thermal envelope/ airtightness through:
- More floor, wall and ceiling insulation.
- Better performing door and window glazing.
Use electricity instead of gas for heating, cooking, and hot water. Use hot water pumps for domestic hot water and heating.
Reduce plug loads with energy-efficient appliances and devices.

Effective principles on both levels:

Consider shrinking and simplifying the building’s footprint. Smaller buildings reduce total heating demand and use less materials, while less complicated footprints are more efficient.
Use durable construction systems and design your building to last longer than 50 years.
Design flexible spaces that occupants can get more use out of.

Other embodied energy design considerations, ranked in effectiveness:

If a building sits on a concrete foundation, the slab alone will account for more than half the embodied energy.
Aluminium window frames add to embodied energy.
Upgrading from single, to double, to triple-glazing increases the embodied energy, even though it improves on thermal efficiency. It is important to understand the trade-off between embodied carbon and thermal performance.

Case Study:

Let’s put these principles to the test in a case study, accompanied by a graph for clarity.

6 variations of the same building are compared below, with different build-ups that influence embodied and operational energy:

Existing 1976 shape with Code loads and Code-minimum insulation: 90 mm timber walls, a truss roof with 140 mm fibreglass insulation, a concrete slab with no insulation, single-glazed aluminium windows and numbers from the Building Code for lighting, plug loads and domestic hot water.
Existing 1976 with Passive House loads: The same construction as above but with Passive House loads for lighting, plug loads and hot water.

It also used a split-unit heat pump for heating and an all-in-one unit for hot water.

Better thermal envelope: To (1) above, 50mm Expanded Polystyrene insulation is added underneath the concrete slab, more wall and ceiling insulation, aluminium windows and standard double-glazing.

The same Passive House loads and heat pump as per (2).

MVHR and uPVC double glazing: As per (3) above, but with a Mechanical Ventilation with Heat Recovery (MVHR) system and uPVC windows (a level up from aluminium) with better double-glazing.
Passive House: The same construction and loads as (4) but with Passive House airtightness performance, slightly more slab insulation and triple-glazed uPVC windows.
Passive House Low Carbon: The same construction and loads as (5) but with a timber floor on piles (equivalent thermal performance to the insulated concrete slab), aluminium-clad timber windows (a level up from uPVC) and a CO2 heat pump for hot water.

Carbon Modelling Assumptions:

It should be noted that this model serves as a general guide. Operational carbon is impacted by assumptions on how a building will be used and what factors are included and excluded from the model.

The key assumptions that influence the model are:

Heat pumps have a Coefficient of Performance (COP) of 3 and the impact of refrigerant leakage is included. For clarity, a COP over 3 is considered good, higher is better.
Electricity is used for cooking.
The building has a 90-year lifespan and the minimum interior temperature is 18 degrees.
The impact of biogenic carbon is included (carbon storage).
FSC-certified timber is used (not including timber door and window frames).
Onsite renewables are not included.

Therefore, with more information and more dedication to low-carbon design, there is always room for improving your project’s carbon output!