According to 'Architecture 2030’ existing buildings generate nearly 40 percent of annual greenhouse gas emissions and about two-thirds of the buildings that are standing today will still be there in 2050. So, this week I'm having a think about how the architectural and building industry is responding to these big challenges and what the average homeowner can do to create energy savings in their existing property to get themselves moving towards that all-important Passive House standard.
We will ever get the opportunity to build our own home from scratch. And of course, there are others who love the home and neighborhood they're already living in and wouldn't want to move anyway but who have houses that don't meet any of the energy certification requirements and that are costing them a fortune in fuel bills each year. And then there's the rapidly growing number of people living in rented accommodation and social housing as a result of the societal move towards greater urbanization and the relentless rise in property prices. The vast majority of those buildings will need to be radically overhauled as part of the global drive towards greater sustainability over the coming decades. So retrofitting looks set to become a crucial activity, not just for private owner occupiers, but also for landlords and municipal authorities.
Retrofitting isn't just about bolting some add-ons like solar panels to your roof to reduce your electricity bills, although that is an extremely good idea in its own right. No, it's really predominantly aimed at greatly reducing energy consumption in the first place by significantly improving the fabric of the building itself to increase its thermal performance and comfort. The challenge is knowing how far to go and how much comfort and performance any retrofit measures will genuinely deliver.
The industry bods have two levels of improvement that they generally refer to. The first is called a shallow retrofit, which is fairly superficial, and may only mean bumping up the insulation in your loft and fitting a more efficient boiler. The second level, unsurprisingly, is called a deep retrofit and it’s a whole different ball game altogether. So how do you know which category your works fall into and what standards are in place to assess them? Well we already know about the Passive House standard but it's almost always physically impossible to reach that lofty goal in an already existing building that wasn't designed that way in the first place, so some allowances have to be made and those are reflected in a globally recognized refurbishment standard called Energy Hit, and a couple of European spin-offs called Out Hit and Euro Hit.
In existing buildings architects are limited by geometry, orientation and structure. There may also be thermal bridges that are difficult to completely eliminate and that provide a path for heat to escape through gaps in existing insulation. The Energy Hit standard takes all that into account and sets a lower performance level than Passive house which can be summarized like this. The building has to achieve a space heating and cooling demand of 25 kilowatt hours per square meter per year compared to the 15-kilowatt hours per square meter per year required for Passive House certification. It also has to reach an air tightness of one air change per hour instead of 0.6 under the Passive house standard. So retrofitting is not easy and while Energy Hit is not as strict as Passive House, it's still a pretty tough standard to achieve.
The first thing to aim for is a high level of internal or external insulation, not just in the walls, but also below the ground floor and in the roof spaces. Retrofitters have to calculate very carefully where to install insulation to achieve the best results without causing other consequential problems. That's trickier than it sounds. For example, if you just stick a bunch of insulation on the interior side of a wall you might make the room warmer but you'll also inevitably make the external wall colder. If that wall is made of a porous material like breeze blocks or some types of brick then you could be blocking off its ability to get rid of moisture, which can result in damp and mould - which you don't want. So if an external wall is very exposed to the elements then the internal insulation may not be your best bet and you'll probably have to consider adding a layer of insulation onto the outside surface which will then typically require a rendered finish. You’ll also need to install high performance triple glazed windows and external doors, and the designers will usually need to consider how they can make significant improvements to the insulation and taping around the window and door frames and cavities as part of any new installation.
Once you've achieved these improvements in the sealing of the building envelope, then just like with Passive house design a mechanical ventilation and heat recovery or MVHR system will need to be installed. You may also be well advised to replace your existing heating system with a ground or air source heat pump. If you are going to take the plunge though and go through the pain of gutting your home to make these major investments in future proofing then there's probably not much point in skimping. The benefit of using the Energy Hit certification as your benchmark is that you'll be forced to comply with the rigors and quality assurance that the standard demands. That means you'll likely need to employ an experienced team of designers and builders who know how to carry out the works to ensure that the air tightness performance is achieved and that there are no hidden shortcuts taken at any stage in the process. The Energy Hit certification process is exactly the same as Passive House certification. To meet the requirements the project must be designed using something called the Passive House Planning Package or PHPP, which is a software-based calculation tool used by architects and planners to assess a building’s heating cooling and primary energy demands and recommend appropriate levels of remedial works. And the finished project has to be certified by an accredited Passive House certifier.
The cost of an Energy Hit retrofit will obviously vary greatly from building to building and from country to country so if you're thinking of embarking upon a project then you should seek the advice of your local Passive house organization. Fortunately, Passive house is now pretty much a global standard so you should have no difficulty getting guidance for your own project. As a very rough rule of thumb though according to the UK home building and renovation website a deep Energy Hit standard retrofit budget will likely be somewhere between £800 and £1000 per square meter with an MVHR unit installation for an average size house coming in at about £10K and triple glazed windows and doors costing around £400 to £600 per square meter. The bulk of the rest of the cost comes from the labor-intensive work to install all the insulations, membranes and intricate tapings around protrusions and junctions that ensure the air tightness measures required to get certification. That work is very time consuming, and it has to be done with great care because much of it is covered up after it's completed and you really don't want remedial works at the end of a project like this. There's no question it's a big financial commitment but depending on where you live there may well be grants and incentives available from state or national government. Over in Ireland for example homeowners can get as much as 50% of their retrofit costs subsidized by that country's Sustainable Energy Authority, and that level of central funding is really something that needs to form part of the green recovery plans in every developed nation in the world.
A deep retrofit project can take a building from an energy performance certificate rating as low as F or G, which is basically a damp leaky shell that's impossible to keep warm in cold weather, all the way up to an A-rated home that comes somewhere close to the energy efficiency of a purpose-built Passive House construction potentially reducing energy demand by 80% and carbon dioxide emissions by 90%. People who've gone through the process talk about the transformation in their comfort and health, with a constant year-round ambient temperature within the whole home, and a lovely crisp clean air supply from the ventilation system, all achieved with negligible heating and cooling bills. And of course, once you've got your official certification you will have significantly improved the value and marketability of your home. In truth the world is miles behind where it should be in applying these energy saving measures to domestic and public buildings, but awareness is growing and the Energy Hit standard is gaining traction in many parts of the world.
The consequence of that is a level of persistent cold and damp that in many cases is causing chronic respiratory illnesses in long-term tenants. But many of the best solutions don't rely on fancy new machines or ambitious and unproven geoengineering concepts. They're right in front of us - hidden in plain sight as they say. Investing rapidly, efficiently and effectively in our existing buildings and national infrastructures will not only massively drive down greenhouse gas emissions but it'll also create hundreds of thousands of well-paid jobs for at least a generation to come.
We will ever get the opportunity to build our own home from scratch. And of course, there are others who love the home and neighborhood they're already living in and wouldn't want to move anyway but who have houses that don't meet any of the energy certification requirements and that are costing them a fortune in fuel bills each year. And then there's the rapidly growing number of people living in rented accommodation and social housing as a result of the societal move towards greater urbanization and the relentless rise in property prices. The vast majority of those buildings will need to be radically overhauled as part of the global drive towards greater sustainability over the coming decades. So retrofitting looks set to become a crucial activity, not just for private owner occupiers, but also for landlords and municipal authorities.
Retrofitting isn't just about bolting some add-ons like solar panels to your roof to reduce your electricity bills, although that is an extremely good idea in its own right. No, it's really predominantly aimed at greatly reducing energy consumption in the first place by significantly improving the fabric of the building itself to increase its thermal performance and comfort. The challenge is knowing how far to go and how much comfort and performance any retrofit measures will genuinely deliver.
The industry bods have two levels of improvement that they generally refer to. The first is called a shallow retrofit, which is fairly superficial, and may only mean bumping up the insulation in your loft and fitting a more efficient boiler. The second level, unsurprisingly, is called a deep retrofit and it’s a whole different ball game altogether. So how do you know which category your works fall into and what standards are in place to assess them? Well we already know about the Passive House standard but it's almost always physically impossible to reach that lofty goal in an already existing building that wasn't designed that way in the first place, so some allowances have to be made and those are reflected in a globally recognized refurbishment standard called Energy Hit, and a couple of European spin-offs called Out Hit and Euro Hit.
In existing buildings architects are limited by geometry, orientation and structure. There may also be thermal bridges that are difficult to completely eliminate and that provide a path for heat to escape through gaps in existing insulation. The Energy Hit standard takes all that into account and sets a lower performance level than Passive house which can be summarized like this. The building has to achieve a space heating and cooling demand of 25 kilowatt hours per square meter per year compared to the 15-kilowatt hours per square meter per year required for Passive House certification. It also has to reach an air tightness of one air change per hour instead of 0.6 under the Passive house standard. So retrofitting is not easy and while Energy Hit is not as strict as Passive House, it's still a pretty tough standard to achieve.
The first thing to aim for is a high level of internal or external insulation, not just in the walls, but also below the ground floor and in the roof spaces. Retrofitters have to calculate very carefully where to install insulation to achieve the best results without causing other consequential problems. That's trickier than it sounds. For example, if you just stick a bunch of insulation on the interior side of a wall you might make the room warmer but you'll also inevitably make the external wall colder. If that wall is made of a porous material like breeze blocks or some types of brick then you could be blocking off its ability to get rid of moisture, which can result in damp and mould - which you don't want. So if an external wall is very exposed to the elements then the internal insulation may not be your best bet and you'll probably have to consider adding a layer of insulation onto the outside surface which will then typically require a rendered finish. You’ll also need to install high performance triple glazed windows and external doors, and the designers will usually need to consider how they can make significant improvements to the insulation and taping around the window and door frames and cavities as part of any new installation.
Once you've achieved these improvements in the sealing of the building envelope, then just like with Passive house design a mechanical ventilation and heat recovery or MVHR system will need to be installed. You may also be well advised to replace your existing heating system with a ground or air source heat pump. If you are going to take the plunge though and go through the pain of gutting your home to make these major investments in future proofing then there's probably not much point in skimping. The benefit of using the Energy Hit certification as your benchmark is that you'll be forced to comply with the rigors and quality assurance that the standard demands. That means you'll likely need to employ an experienced team of designers and builders who know how to carry out the works to ensure that the air tightness performance is achieved and that there are no hidden shortcuts taken at any stage in the process. The Energy Hit certification process is exactly the same as Passive House certification. To meet the requirements the project must be designed using something called the Passive House Planning Package or PHPP, which is a software-based calculation tool used by architects and planners to assess a building’s heating cooling and primary energy demands and recommend appropriate levels of remedial works. And the finished project has to be certified by an accredited Passive House certifier.
The cost of an Energy Hit retrofit will obviously vary greatly from building to building and from country to country so if you're thinking of embarking upon a project then you should seek the advice of your local Passive house organization. Fortunately, Passive house is now pretty much a global standard so you should have no difficulty getting guidance for your own project. As a very rough rule of thumb though according to the UK home building and renovation website a deep Energy Hit standard retrofit budget will likely be somewhere between £800 and £1000 per square meter with an MVHR unit installation for an average size house coming in at about £10K and triple glazed windows and doors costing around £400 to £600 per square meter. The bulk of the rest of the cost comes from the labor-intensive work to install all the insulations, membranes and intricate tapings around protrusions and junctions that ensure the air tightness measures required to get certification. That work is very time consuming, and it has to be done with great care because much of it is covered up after it's completed and you really don't want remedial works at the end of a project like this. There's no question it's a big financial commitment but depending on where you live there may well be grants and incentives available from state or national government. Over in Ireland for example homeowners can get as much as 50% of their retrofit costs subsidized by that country's Sustainable Energy Authority, and that level of central funding is really something that needs to form part of the green recovery plans in every developed nation in the world.
A deep retrofit project can take a building from an energy performance certificate rating as low as F or G, which is basically a damp leaky shell that's impossible to keep warm in cold weather, all the way up to an A-rated home that comes somewhere close to the energy efficiency of a purpose-built Passive House construction potentially reducing energy demand by 80% and carbon dioxide emissions by 90%. People who've gone through the process talk about the transformation in their comfort and health, with a constant year-round ambient temperature within the whole home, and a lovely crisp clean air supply from the ventilation system, all achieved with negligible heating and cooling bills. And of course, once you've got your official certification you will have significantly improved the value and marketability of your home. In truth the world is miles behind where it should be in applying these energy saving measures to domestic and public buildings, but awareness is growing and the Energy Hit standard is gaining traction in many parts of the world.
The consequence of that is a level of persistent cold and damp that in many cases is causing chronic respiratory illnesses in long-term tenants. But many of the best solutions don't rely on fancy new machines or ambitious and unproven geoengineering concepts. They're right in front of us - hidden in plain sight as they say. Investing rapidly, efficiently and effectively in our existing buildings and national infrastructures will not only massively drive down greenhouse gas emissions but it'll also create hundreds of thousands of well-paid jobs for at least a generation to come.
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