How Does Hempcrete Perform In A Cold Climate? A Look At Thermal Mass And Insulation
Hempcrete is a viable and effective building material that has a positive effect on the environment instead of a negative one.
As the conversation on the environment gathers pace rapidly, the attention on carbon neutral or negative building materials increases and hempcrete is one of the leading eco friendly building materials in the world right now.
Hempcrete is an excellent building material when it comes to colder climates for a number of reasons. Hempcrete stores heat in its walls that it releases slowly as the temperature cools.
It can do this with heat from the sun and internal heat sources. it is available in a number of forms for different projects and it has a number of significant benefits as well as some potential drawbacks.
Hempcrete Has Thermal Mass As Well As Insulation
The main advantage of Hempcrete is that it stores heat and releases it slowly into the house.
Even in a cold climate, if you get any sun during the day, the hempcrete walls will store that energy, releasing it slowly for hours afterwards.
Hempcrete will also store any internal heat in the same way. If you have your heaters or oven on, that heat will also be absorbed and released slowly which can lead to a significant energy saving as well as helping the planet.
The way hempcrete releases air slowly allows you to open the window when it gets too hot, knowing you won’t lose all your heat out the window.
The second advantage for those in a cold climate is that the slow release acts as a regulator of temperature. While the heat may only rise for a limited number of hours, hempcrete can store that heat and release it over hours.
How The Hempcrete Is Mixed
A lot of how your hempcrete building will perform is based on how the hempcrete is mixed. Hempcrete walls will usually be around 300mm to 400mm plus in thickness and typical thermal conductivity is .05 – .09 W/mK, again depending on how the material is made.
All in all, the quality of the hemp you use will have a massive impact on the amount of benefit you will get.
We always recommend getting any of your products, mixes or blocks from a reputable company.
Hempcrete On Site Mix
Many companies supply a hempcrete on site mix that you can order for any size project. This will include bags of hemp stalk or which and a lime binder which will be wet mixed with to form the hempcrete.
The hempcrete will be placed between two plaster boards until it has dried enough the sides to be complete. The walls will require a further 8 weeks to fully dry before they can be plastered. This may be even more if you are in a colder climate.
Check out This Awesome On Site Hempcrete Building Video On Youtube:
Plenty of companies now also offer hempcrete blocks which come pre cast without any drying times. You lose the carbon negative impact but the building can be completed much more quickly and without the extended drying time.
Hempcrete comes with the downside of not being a supporting material so it usually needs to be used in conjunction with other building materials for steady footings and load bearing walls. Also on the market at the moment, there is
Having lived in a clod climate in Ireland where the houses can be impossible to heat up, Hemp/Lime plastering is a life saver. If you have a cold room and you touch the walls or the floor and they are freezing cold with no prospect of heating up. Hemp Lime plaster will absorb whatever heat is there and radiate it slowly into the room. Just like hempcrete to is perfect for external heat sources and internal ones.
Hempcrete plater is pretty simple to put together if you follow this simple recipe or follow along with this guide:
The following is a Hemp/Lime plaster recipe used in Ireland for decades:
2 Buckets Of Hydraulic Lime
3 buckets Of Water
4 Buckets Of Ground Hemp Stalk Chippings
This is going to make a lovely sticky hemp plaster that will roll on lovely and allow you to have a quality insulating, heat radiating hemp plaster for your home.
Actually, getting the hemp plaster to stick to the wall can be a bit tricky. You kind of have to smooth and press it on but once it sticks you can add more. You can give it a bit of time before you smooth it out with a rubber glove on.
You can use any thickness but the more you use, the more of the insulating and slow release heat benefits you will get.
Hemp mortar is one of the best ways the insulate a roof. Mixed in relatively the same recipe as the plaster this can be used instead.
Place loose hemp chippings down on the roof and then cover with the hemp mortar.
You’re going to lose most of the heat from your home through the roof and we find this hemp insulation to far outperform the insulation that has been traditionally used but doesn’t release heat slowly.
Other Benefits Of Building With Hemp
Carbon Negative & Environmental
Every building built using Hempcrete will absorb and store a large amount of carbon dioxide and this will help environmentally but also how environmentally friendly hemp is to grow.
If 500,000 new homes were built in the US in 1 year with hempcrete (2,000 square feet each), they would absorb nearly 2 million tons of Carbon, if those same homes were insulated using fibreglass, they would emit almost 500,000 tons of carbon so this is a healthy saving for the planet.
It needs 30% less water to make hempcrete blocks as it does to make concrete ones and the hurd or stalk chippings used in hempcrete, is a by product of the plant anyway. Hemp absorbs carbon as it grows and releases oxygen, and it rids the soil of toxins unlike other plants which drain the soil. It requires minimal nutrients to grown and doesn’t require any pesticides.
If we are serious about the environment then Hempcretes positive environmental impact surely cannot be overlooked as it can be used for new buildings and renovating old ones.
Good Fire and Pest Resistance
Hempcrete is also a highly fire resistant substance with Hempcrete in the Uk giving it a 1 hour burn rating.
If you have safety in mind when building your home then hempcrete is an option not to be overlooked.
It is also naturally pest resistant which means that no additional pesticides and harsh chemicals need to be added to the plant as it grows.
Hempcrete Absorbs Moisture
Hempcrete is a vapour malleable building material which means it absorbs moisture as well as acting as an insulation. It absorbs the moisture when the humidity is high and releases it when it gets lower.
This breathing material is far healthier for the building over time and for its occupants than traditional buildings which lock the moisture in and remains damp leading to health issues for the occupants.
Cons Of Working With Hempcrete
There are a few disadvantages of working with Hempcrete that will vary depending on your project and the experience of the builders. Here are a few of the obstacles of working with Hempcrete.
Higher Up Front Costs
Because hempcrete is not used as much in construction, you don’t get the cheaper prices of mass produced materials and may have to pay slightly more for your hempcrete project.
That being said, building with hempcrete or using it for the frame walls will definitely not cost significantly more than traditional materials.
The savings that you can make on heating costs can be significant and the breathable material means you don’t need to use air conditioning.
It Can’t Be Used For Load Bearing Walls
Hempcrete can only be used for frame walls and using loading bearing hempcrete blocks will increase the carbon footprint of your home but it will still be much less than traditional building materials.
Hempcrete can only be used in conjunction with other materials for a full house build but it can used for floor slabs, attic insulation, frame walls and plastering to give you and the planet plenty of the benefits of hemp in your new build or renovation.
Finding Experienced Contractors
Hempcrete is a relatively new building material and as such there aren’t as many experienced contractors with hempcrete.
This is especially true in the US where Hemp has just become federally legal again in 2018 with the passing of the farm bill. The hempcrete market is kicking off though with more and more attention on making environmentally clean buildings.
On larger scale projects, inexperienced contractors have tried to use hempcrete in the same way as traditional materials and more encounter problems. If you are in doubt, you should always contact experienced contractors.
The Recent Growth Of Hempcrete
Hempcrete kicked off in France in the 90’s and has grown in popularity there ever since, it has also spread throughout the rest of Europe including the UK and Ireland.
Hemp buildings have been a feature of European buildings for centuries but building with hemp in the USA is something that is experiencing huge growth.
As the issue of climate change and golbal warming continues to gain more and more momentum, sustainable building materials such as hempcrete will become more and more in demand.