Key to low-energy homes
If your home is to be ‘fit for purpose’ it should be . . . . . . Efficient; envelope, ventilation, thermal mass & simple care = minimal energy. A truly sustainable home ideally consumes no more energy to build or run than it captures, and the building products & process leave little or no dent in our environment or health. It's a good concept and congratulations to those who have achieved this, however it is too much to ask of every new-build as it would seem unrealistic as most challenges vary depending on the environment, resources & Law. You CAN get close to this with impressive results by avoiding gimmicks and sticking to basic building physics. Ref. CMHS, Passivhaus Healthy; ventilation & safe building products = good air quality Most of us who take building seriously are more than aware that air quality has rapidly declined over the last 50 years. Some improvements were made in the form of common bathroom extracts and trickle vents, but neither work particularly well and have no energy recovery and so expel airborne energy. Since early use in Canada in the 70's, MVHR has long been the common sense option for new-builds in countries where building physics is widely understood. The UK has taken a lot longer but things are finally moving. The MVHR industry is fairly young so we must continue to closely observe progress. The key to a good system lies in design and planning with strong focus on ducting. A good MVHR system will provide continuous fresh air, remove contaminants and recover most airborne energy. Try you're best to avoid products that leak chemicals such as MDF synthetic furniture etc. More watered plants indoors will also help balance your indoor environment. Durable; well designed drainage & ventilation = long lasting structures. We take for granted that our engineers get structural load calculations right, and the industry has come a long way in fire prevention. The most common causes of building deterioration are cold bridging, moisture bottle-necking and poor airflow. This is mainly from lack of understanding of moisture & air movement at the design stage. Site experience in dealing with old/new, good/bad, structures is a huge advantage in all design but particularly in durability. Good Whole-House-Ventilation such as MVHR ensures adequate internal air management, whilst thourgh design/install of membranes, drip control & cavitys will prevent moisture build-up. Comfortable; warmth, space, air, light & security. Nearly all of us have grown used to, expect, or would like warmth, space, light & security when needed in our climate. Good warmth & light in particular, are fairly recent luxuries ,while air quality has generally deteriorated. In order to keep these comforts and improve air-quality we need better understanding, design, & construction practices. Affordable; invest in preparation, homework and practice & save on unnecessary technology Low energy homes don't have to cost more to build than conventional. Excessive costs are usually down to the following; 1. Awkward or incomplete design details. 2. Excessive glazing 3. Hi-spec, labour intensive products like rigid foiled insulation and ridiculous tapes. 4. Specifying of unnecessary heating. 5. lack of experience and knowledge in efficient envelopes (especially air-tightness). 6. poor access, untidy sites & wasted/damaged materials. For your build to be cost effective, the build needs to be smooth. This means clear work areas, organised space, fixed access to high areas, good lighting, minimum waste and disciplined scheduling. Above all remember that making design changes during the build costs money & time. Certified; recognised standards met, certification & some box ticking. Ultimately to be able to borrow money, insure and move into your new home, you need to satisfy Building Control and lenders etc. This can be onerous for the architect and client, especially when trying to specifying ventilation or miss-understanding air-tightness targets. What is important to remember is that while SAP calculations & EPCs are necessary in the UK, they are not an accurate assessment as they are still in their development stage. Do what is required for Building Control but always stick to basic building physics and reference proven practices from CMHC, Passivhaus etc. J. A. Reid |