Providing Fresh Air in Our Home

Tags: , , , , , , ,

Providing Fresh Air in Our Home

first_imgOne of the features in our new house that I’m most excited about barely raises an eyebrow with some of our visitors: the ventilation system. I believe we have the highest-efficiency heat-recovery ventilator (HRV) on the market — or at least it’s right up there near the top.I’ll describe this Zehnder HRV and its impressive specifications and features — but not until next week. This week I’ll provide a little background on ventilation. Ventilation optionsVentilation can take many different forms. Very generally, systems can be categorized into about a half-dozen generic types:No ventilation. This is almost certainly the most common option in American homes. There is no mechanical system to remove stale indoor air (and moisture) or bring in fresh outside air. In the distant past, when buildings weren’t insulated, this strategy worked reasonably well — relying on the natural leakiness of the house.It’s worth noting, though, that even a leaky house doesn’t ensure good ventilation. For this strategy to work there has to be either a breeze outside or a significant difference in temperature between outdoor and indoors. Either of these conditions creates a pressure difference between indoors and out, driving that ventilation. On calm days in the spring and summer, there might be very little air exchange even in a really leaky house.Natural ventilation. In this rather uncommon strategy, specific design features are incorporated to bring in fresh air and get rid of stale air. One approach is to create a solar chimney in which air is heated by the sun, becomes more buoyant, and rises up and out through vents near the top of the building; this lowers the pressure in the house, which draws fresh air in through specially placed inlet ports. The rest of this blog will focus on mechanical ventilation.Exhaust-only mechanical ventilation. This is a relatively common strategy in which small exhaust fans, usually in bathrooms, operate either continuously or intermittently to exhaust stale air and moisture generated in those rooms. This strategy creates a modest negative pressure in the house, and that pulls in fresh air either through cracks and other air-leakage sites or through strategically placed intentional make-up air inlets. An advantage of this strategy is simplicity and low cost. A disadvantage is that the negative pressure can pull in radon and other soil gases that we don’t want in houses.Supply-only ventilation. As the name implies, a fan brings in fresh air, and stale air escapes through cracks and air-leakage sites in the house. The air supply may be delivered to one location, dispersed through ducts, or supplied to the ducted distribution system of a forced-air heating system for dispersal. A supply-only ventilation system pressurizes a house, which can be a good thing in keeping radon and other contaminants from entering the house, but it risks forcing moisture-laden air into wall and ceiling cavities where condensation and moisture problems can occur.Balanced ventilation. Much better ventilation is provided through a balanced system in which separate fans drive both inlet and exhaust airflow. This allows us to control where the fresh air comes from, where that fresh air is delivered, and from where exhaust air is drawn. Balanced ventilation systems can be either point-source or ducted. With ducted systems, it makes sense to deliver fresh air to spaces that are most lived in (living room, bedrooms, etc.) and exhaust indoor air from places where moisture or pollutants are generated (bathrooms, kitchen, hobby room).Balanced ventilation with heat recovery. If there are separate fans to introduce fresh air and exhaust indoor air, it makes a lot of sense to locate these fans together and include an air-to-air heat exchanger so that the outgoing house air will precondition the incoming outdoor air. This air-to-air heat exchanger — more commonly referred to today as a heat-recovery ventilator or HRV — is the way to go in colder climates. A slightly different version, known as an energy-recovery ventilator (ERV), is similar but transfers moisture as well as heat from one airstream to the other, keeping more of the desirable humidity in the house in the winter and reducing the amount of humidity introduced from outdoors in the summer. Alex is founder of BuildingGreen, Inc. and executive editor of Environmental Building News. In 2012 he founded the Resilient Design Institute. To keep up with Alex’s latest articles and musings, you can sign up for his Twitter feed. RELATED ARTICLES Designing a Good Ventilation System GBA Encyclopedia: Ventilation ChoicesAre HRVs Cost-Effective?HRV or ERV?A New Way to Duct HRVsVentilation Rates and Human HealthHow Much Fresh Air Does Your Home Need? Joseph Lstiburek: Just Right and Airtightcenter_img Tight homes need mechanical ventilationI’ll focus more on HRVs in next week’s blog, especially our new high-efficiency Zehnder system. Following that I’ll address why commissioning an HRV is so important and how that’s done — or at least how it was done with our system.I’m a firm believer that all homes should have mechanical ventilation. With better-insulated, tighter homes, that ventilation is all the more important. But even in a very leaky house, one can’t count on bringing in much fresh air or calm days in the spring and fall when there isn’t a pressure differential across the building envelope.If budgets allow, going with balanced ventilation is strongly recommended, and if you’re doing that in a relatively cold climate, like ours, then providing heat recovery is a no-brainer. Mechanical ventilation always takes energy; with heat recovery the energy penalty of fresh air is minimized. Why ventilate?For centuries homes weren’t ventilated, and they did all right, didn’t they? Why do we need to go to all this effort (and often considerable expense) to ventilate houses today?There are several reasons that ventilation is more important today than it was long ago. Most importantly, houses 100 years ago were really leaky. Usually they didn’t have insulation in the walls, so fresh air could pretty easily enter through all the gaps, cracks, and holes in the building envelope.Also, the building materials used 100 years ago were mostly natural products that didn’t result in significant offgassing of volatile organic compounds (VOCs), formaldehyde, flame retardants, and other chemicals that are so prevalent in today’s building materials, furnishings, and belongings.last_img read more

Continue Reading

Beta Testing At Spiceworks: A Surprising Place To Find Qualified Guinea Pigs

first_imgrieva lesonsky Related Posts How to Get Started in China and Have Success Tags:#Beta Testing#networking#small business#startups Beta testing can be a bitch – especially when you’re working with complex business technology that doesn’t make sense for consumers. It can be incredibly difficult to find good test subjects with enough of a knowledge base to give you intelligent feedback on these kinds of sophisticated products.That’s exactly the issue facing Pertino as it prepared to launch its cloud-based network launch last fall.Where To Find Qualified Beta Testers?Pertino’s concept was to build a cloud-based global network, requiring no specialized hardware or virtual private networks. The company envisioned a network affordable enough for small and midsize (SMB) companies with the security and performance of an enterprise network.How the heck do you beta test a product like that?Pertino CEO Craig Elliott turned to the Spiceworks.com community of more than 2.4 million IT professionals, centered around the company’s free, ad-supported IT management tools for SMBs.Elliott and many Pertino employees were already Spiceworks members, and they started with a 20-company private beta program that grew into “a community-exclusive public beta” involving 250 “Spiceheads.”Spiceworks’ co-founder Jay Hallberg says three to four years ago the Spiceworks team was “dreaming big that someday we’d have a company launch within Spiceworks.” Pertino turned out to be that company. Beta Testing Feedback Is EssentialWhile the usual point of beta testing is to find out if your product is good enough to launch, most initial offerings end up requiring signficant tweaks. “If you’re not thoroughly embarrassed by the first product you release,” Elliott says, “you’ve overthought it, and you’ve come to market too late.”Beta testing in Spiceworks enabled knowledgeable IT professionals to actually use the product and offer Pertino “incredible, first-hand feedback and insights,” says Elliott.Todd Krautkremer, Pertino’s VP of marketing, explains that, “Since so many members of the Spiceworks community work IT at small and mid-sized businesses, it was a way to treat SMBs as consumers… The Spiceheads provided feedback in real time [that] shaved months off what the normal development timeline would be.” Beta testing in Spiceworld gave Pertino “validation and the ability to go back to the drawing board based on the feedback,” Krautkremer adds. If you can’t make it in the Spiceworks community, how can you succeed in the broader market?Speed WinsPertino didn’t worry about launching its “private” beta to such a large community. “”In the world of open-source tech,” says Krautkremer, “to rest your laurels on defensible IP is not a recipe for success.” Patents can’t protect you.Instead, seizing the market as early as possible is the best way to become a dominant leader, says Krautkremer. It’s not necessarily being first to market,” Krautkremer continues, “MySpace was there before Facebook.” To win, your idea has to be novel and simple, and you have to pursue it aggressively.So far, that approach is working for Pertino. The company publicly launched its product in February: “6,000 people downloaded it on day one,” Krautkremer says, and more than 300 Pertino networks were built.Beta Test TipsSharing what he learned from the Spiceworks beta, Krautkremer offers tech companies 4 quick tips:Use the freemium model: make it easy for potential customers to try your product.Keep it simple: “Click, click, done wins. Click, click, click, done loses.”Eat your own dogfood: use and test your own product.Get to market first and then grow fast.Oh, and find qualified beta testers to provide useful feedback before you make your product publicly available.center_img China and America want the AI Prize Title: Who … How OKR’s Completely Transformed Our Culture What Nobody Teaches You About Getting Your Star…last_img read more

Continue Reading